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  • Physics  (10,646)
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  • 101
    Electronic Resource
    Electronic Resource
    A new approach for estimating the recrystallization rate and equilibrium melting temperature (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 133-141 
    Details
    ISSN: 0887-6266
    Keywords: recrystallization rate ; equilibrium melting temperature ; differential scanning calorimetry (DSC) ; poly(butylene terephthalate) (PBT) ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method is described for measuring the heat and rate of recrystallization following partial melting. The method uses a specific sequence of temperatures with a differential scanning calorimeter, and the melting and recrystallization processes were confirmed by optical observations. The method was applied to poly(butylene terephthalate). The rate of recrystallization was found to be roughly two orders of magnitude faster than isothermal crystallization from the melt. The melting temperatures obtained from recrystallization were used in the Hoffman-Weeks equation to deduce 236°C as the equilibrium melting temperature for poly(butylene terephthalate). © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 133-141, 1998
    Additional Material: 10 Ill.
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  • 102
    Electronic Resource
    Electronic Resource
    Integral sorption in rubbery polymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 171-180 
    Details
    ISSN: 0887-6266
    Keywords: integral sorption ; rubbery polymers ; moving boundaries ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Simple equations are derived that describe integral sorption and desorption experiments under conditions where moving boundary effects in polymer films and spheres can be large because of high solvent concentrations. General conclusions are formulated about the nature of sorption and desorption experiments for both rectangular and spherical geometries. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 171-180, 1998
    Additional Material: 5 Ill.
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  • 103
    Electronic Resource
    Electronic Resource
    Modeling the effect of crosslinking in methyl-pendant poly(p-phenylene benzobisthiazole) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 3057-3064 
    Details
    ISSN: 0887-6266
    Keywords: methyl-pendant PBZT ; crosslinking ; molecular modeling ; compressive strength ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Molecular mechanics and dynamics simulations have been performed on methyl-pendant PBZT to study the effects of intermolecular crosslinking. Several possible crosslinked structures were investigated. The effect of crosslinking was found to be strongly dependent upon crosslink type and, in some instances, crosslink density. A significant axial stress is predicted to occur upon the formation of phenyl-to-phenyl type crosslinks. This provides a reasonable explanation for the experimental observation of transverse cracks in the skin of crosslinked, MePBZT fiber. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3057-3064, 1998
    Additional Material: 8 Ill.
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  • 104
    Electronic Resource
    Electronic Resource
    Interfacial thickness in bilayers of poly(phenylene oxide) and styrenic copolymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 3115-3125 
    Details
    ISSN: 0887-6266
    Keywords: interfacial thickness ; PPO ; SAN ; SMA ; neutron reflectivity NR ; binary interaction energies ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Estimates for the thickness of the interface between poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) and copolymers of styrene-acrylonitrile (SAN) and styrene-maleic anhydride (SMA) based on the theory of Helfand and Tagami are compared to neutron reflectivity (NR) measurements. Good agreement is found between the NR measurements and theoretical predictions that make use of a mean field binary interaction model and previously reported binary interaction energies. The techniques outlined in this work may be used to understand relationships between the mechanical properties of multiphase polymer blends and the fundamental thermodynamics of polymer interactions. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3115-3125, 1998
    Additional Material: 7 Ill.
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  • 105
    Electronic Resource
    Electronic Resource
    Viscoelastic effects in cutting of elastomers by a sharp object (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1283-1291 
    Details
    ISSN: 0887-6266
    Keywords: cutting ; elastomer ; viscoelastic behavior ; crack tip diameter ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cutting behavior of elastomers by a sharp object was investigated using various elastomers such as acrylonitrile-butadiene rubber (NBR), styrene-butadiene rubber (SBR), and natural rubber (NR). The effects of crosslinking density, cutting rate, and temperature on the cutting energy of elastomers were investigated. The cutting behavior of swollen elastomers was also investigated. It was found that the cutting energy increased as the molecular weight between crosslinks increased. It was also found that the cutting energies of various elastomers did not yield a single line. Moreover, even in the threshold condition of cutting process, the cutting energy was much higher than the threshold fracture energy. These results suggest that the cutting behavior cannot be explained by only a C—C bond rupture process, but it includes other energy dissipation processes. The curves for cutting energies obtained at different cutting rates and temperatures were well superimposed on a single master curve when they were shifted using the WLF (Williams, Landel, and Ferry) equation. Therefore, it is supposed that the cutting of elastomers by a sharp object includes viscoelastic energy dissipation process and is the viscoelastic behavior. It was also found that the variation of cutting energy over a considerable range of effective rates was smaller than that of the tear energy. It is attributed to the fact that the change of the crack tip diameter, i.e., roughening or reduction, was restricted by the diameter of razor blade. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1283-1291, 1998
    Additional Material: 9 Ill.
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  • 106
    Electronic Resource
    Electronic Resource
    Surface correlation effects on gloss (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1321-1334 
    Details
    ISSN: 0887-6266
    Keywords: gloss ; rough surface ; specular reflectance ; correlation length ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A general expression for gloss within the scalar Kirchhoff's theory is derived in terms of the detector collecting angle, and two statistical parameters that characterize the surface roughness. Analytical expressions for gloss are derived for an exponential and a Gaussian correlation function, and numerical results for these and other quasi-exponential correlation functions are presented. It is shown that the incoherent contribution to gloss is significant in common polymeric surfaces. The latter implies that surface height correlations cannot be neglected in the evaluation of gloss. It is also shown that for a correlation function with a single characteristic length, gloss scales with the correlation length Lc in the same way as with the detector collecting angle. This fact can be used to determine Lc with a glossmeter, and an experimental method to achieve this is proposed. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1321-1334, 1998
    Additional Material: 12 Ill.
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  • 107
    Electronic Resource
    Electronic Resource
    Transcrystallization of PTFE fiber/PP composites - III. Effect of fiber pulling on the crystallization kinetics (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1361-1370 
    Details
    ISSN: 0887-6266
    Keywords: transcrystallinity ; PTFE fiber/PP composites ; heterogeneous nucleation ; crystal growth rate ; orientation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of shear rates on the transcrystallization of polypropylene (PP) on the polytetrafluoroethylene (PTFE) fibers has been quantitatively investigated using a polarized optical microscope equipped with a hot stage and a tensile testing machine. The PTFE fibers were pulled at different rates, from 0.17 to 8.33 μm/s, to induce a range of shear rates, about 0.02 to 1.16 1/s, in the PP melt adjacent to the fiber. The induction time, nucleation rate, and saturated nucleation density at the fiber surface were determined at various crystallization temperatures. It was found that both the nucleation rate and the saturated nucleation density increase with increasing shear rates. However, the induction time is significantly reduced. Based on the theory of heterogeneous nucleation, the interfacial free energy difference functions Δσ;TCL of PP on PTFE fibers at different levels of shear rates were determined and compared with that obtained from crystallization under quiescent conditions. Results showed that the magnitude of ΔσTCL decreased to be about one-third of that for the quiescent crystallization, when a shear rate of 1.16 1/s was applied. The application of a shear stress to the supercooled PP melt by fiber pulling leads to enhance the development of transcrystallinity. Moreover, both the thickness and the crystal growth rate of transcrystalline layers were found to increase with the increasing rate of fiber pulling, especially at low crystallization temperatures where regime III prevails (see text). Surface morphology of PTFE fibers was revealed using a scanning electron microscope and an atomic force microscope. It is argued that the presence of fibrillar-type features at the fiber surface is the main factor responsible for the development of transcrystallinity. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1361-1370, 1998
    Additional Material: 14 Ill.
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  • 108
    Electronic Resource
    Electronic Resource
    Towards a better mixing of two incompatible polymers by casting from solution without compatibilizer (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1051-1060 
    Details
    ISSN: 0887-6266
    Keywords: polymer mixtures ; film casting ; solvent selectivity ; incompatibility ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of polystyrene/poly(oxyethylene) (PS/POE) and polystyrene/poly-(methyl methacrylate) (PS/PMMA) have been obtained by casting from solution. Differential Scanning Calorimetry, Optical Microscopy, and Scanning Electron Microscopy showed that two incompatible polymers can present relatively good miscibility (formation of domains smaller than 5 μm) when the solvent from which the films are obtained does not present any noticeable selectivity towards the two polymers of the blends. An increase of the casting temperature increases the miscibility of PS and PMMA because the selectivity of the solvent used, towards these polymers decreases with increasing temperature. On the contrary, an increase of the casting temperature in the case of the PS and POE mixture decreases their miscibility because the selectivity of the solvent used increases with increasing temperature. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1051-1060, 1998
    Additional Material: 9 Ill.
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  • 109
    Electronic Resource
    Electronic Resource
    Sorption of small molecules in various polycarbonates and Kapton-H (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 483-494 
    Details
    ISSN: 0887-6266
    Keywords: small penetrants ; sorption isotherms ; site distribution ; elastic distortion ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Pressure-composition isotherms were determined at 20°C for CO2 in Kapton and various substituted polycarbonates and for H2O, Ar, N2, CH4, and acetone in bisphenol-A-polycarbonate. The isotherms are described by two parameters an average free energy of sorption and a width of a Gaussian distribution of free sorption energies. Within the framework of a recent model these parameters can be calculated assuming an elastic distortion of the polymer caused by the incorporation of solute atoms in preexisting holes. By comparing experimental values with predictions of the model the experimental width of the free energy distribution is only 30% smaller than the theoretical one. Functional relationships are obeyed between the sorption parameters on the one hand and glass transition temperature, average hole volume, and molecular volume of the solute on the other hand. Deviations occur for larger molecules like acetone and ethylene which are attributed to a viscoelastic distortion of the polymer. Comparing free energies of solution for the rubbery and glassy state of the polymer reveals more negative values for the glassy polymers despite their extra elastic distortion energy. This discrepancy is overcome by taking into account that the occupied volume has to be re-formed in the case of the rubbery or liquid polymer. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 483-494, 1998
    Additional Material: 12 Ill.
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  • 110
    Electronic Resource
    Electronic Resource
    On the interfacial energy of extended-chain crystals from polyethylene melt by revised Flory equations of fusion (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1293-1303 
    Details
    ISSN: 0887-6266
    Keywords: extended-chain crystals ; low molecular weight linear polyethylene ; revision of Flory's theory of fusion ; interfacial free energy ; bulk-isothermal crystallization ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To analyze extended-chain crystalline systems composed of linear polyethylene, Flory's conventional theory of fusion is reconsidered by introducing a new concept of crystallinity. When this new treatment is applied to a melting case of a low molecular weight polyethylene fraction (Mn = 5600) isothermally bulk crystallized, a certain result that very large lamellar thickness was caused by a very small increase in crystallization temperature can satisfactorily be explained by a significant change in interfacial free energy of the crystallite end. Further, it shows 14-17 kJ/mol as a nonequilibrium value range of interfacial free energy for highly crystalline polyethylene fractions of low molecular weight Mn ≦ 5600 by using the previous data presented by other workers. A similar result is also obtained on the Mn = 5600 fraction by analyzing from a standpoint of equilibrium crystallinity. In either case, the estimated range of interfacial free energy is consistent with the conventional range. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1293-1303, 1998
    Additional Material: 2 Ill.
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  • 111
    Electronic Resource
    Electronic Resource
    Analysis of crystallization kinetics of poly(ether ether ketone) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1335-1348 
    Details
    ISSN: 0887-6266
    Keywords: PEEK ; growth rate ; crystallization ; kinetics ; regime ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An optical microscope equipped with a video photograph system was used to follow the growth of spherulites. Under nitrogen atmosphere, the growth rates at 290 and 300°C suggest that when the melt of PEEK has been equilibrated for 15 min at 400°C, the subsequent crystallization behavior was nearly independent of the prior thermal history. Linear growth rates of crystallization of PEEK have been measuredin the temperature range of 260-325°C for melt-pressed films and solvent cast films. Detailed kinetic analysis indicated that PEEK exhibited an unmistakable regime II → III transition at 296 ± 1°C. The II → III transition was clearly present irrespective of the rather drastic changes in U*. It is interesting that the branching and crosslinking retarded the growth rate of PEEK, but a transition from regime II to regime III still existed. For melt-pressed films after equilibration at 400°C for 15 min, values of σ and q suggest that U* should be taken nearer to 1500 cal/mol in the case of T∞ = Tg - 30 K and 2000 cal/mol in the case of T∞ = Tg - 51.6 K. The Kg(III)/Kg(II) ratio (1.32) was not as close to the predicted value of 2 as was Hoffman's ratio. For PEEK, the Thomas-Staveley constant (β) should be closer to 0.25 or 0.3 instead of 0.1. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1335-1348, 1998
    Additional Material: 6 Ill.
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  • 112
    Electronic Resource
    Electronic Resource
    Subglass-transition-temperature annealing of poly(ethylene terephthalate) studied by FTIR (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 783-788 
    Details
    ISSN: 0887-6266
    Keywords: poly(ethylene terephthalate) ; sub-Tg ; annealing ; conformation ; infrared spectra ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using FTIR spectroscopy we have examined conformational changes in the quenched and slowly cooled amorphous PET films during physical aging process. It was observed that the amount of trans conformers for quenched sample decreased upon sub-Tg annealing. For the slowly cooled sample that corresponds to a state closer to equilibrium, the amount of trans conformers hardly decreased, but increased gradually during sub-Tg annealing process. The conformational populations of these two samples tend to be identical with annealing time. These results demonstrate that sub-Tg annealing will lead to closer interchain packing and result in the formation of new cohesional entanglements along the chains. In situ FTIR studies on the conformational changes of these samples were also carried out during heating up of the sample through the glass transition region. The results showed that incremental changes of the amount of trans conformers in Samples Q and SC were gradual, while an abrupt change of trans conformers occurred in the sub-Tg annealed samples. These results were in agreement with the formation of the interchain cohesional entanglement due to sub-Tg annealing. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 783-788, 1998
    Additional Material: 6 Ill.
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  • 113
    Electronic Resource
    Electronic Resource
    Mechanical properties and the two-phase structure inside the heterophase domains of blends from HDPE and SBS star block copolymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1423-1432 
    Details
    ISSN: 0887-6266
    Keywords: recycling ; polyolefine modification ; mechanical properties ; SAXS ; disorder ; compatibilizer ; blend ; block copolymers ; polyethylene ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends from polyethylene (PE) and polystyrene-b-polybutadiene-b-polystyrene star block copolymers (SBS) (thermoplastic elastomers) are studied with polyolefine recycling in view. Each component, dispersed in a heterogeneous blend, exhibits a two-phase morphology. This structure is investigated by small angle X-ray scattering (SAXS) and compared to mechanical properties as a function of SBS grade and content. Increasing the SBS content one observes a vanishing PE-related long period reflection, while an SBS-related peak emerges. Best mechanical properties are obtained at concentrations, where the width of the observed long period reflection is broadest. For a quantitative analysis of the SAXS, the interface distribution function (IDF) analysis is employed. Data are fitted with a function modeling arrangement as well as disorder of domains inside the two different kinds of dispersed grains. The analysis yields that the observed broadening of the long spacing peak is caused only by an increased fluctuation of the thicknesses of amorphous layers in the PE stacks. This fluctuation again decreases for SBS concentrations beyond 15 wt %. The effect is strongest for blends containing the SBS grade with the lowest molecular weight and is discussed in terms of its compatibilization effect. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1423-1432, 1998
    Additional Material: 7 Ill.
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  • 114
    Electronic Resource
    Electronic Resource
    Molecular mobility of substituted poly(p-phenylenes) characterized by a range of polymer relaxation techniques (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1465-1481 
    Details
    ISSN: 0887-6266
    Keywords: poly(phenylene) ; dielectric ; dynamic mechanical ; relaxation ; free volume ; positron annihilation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The free volume and related mobility properties of substituted poly(p-phenylene) polymers are examined. The techniques used range from positron annihilation, dielectric relaxation, and dynamic mechanical spectroscopy to thermally stimulated currents. Fractional free volume is determined for the samples with different substituted side groups and related to the glass transition temperature. Bulkier groups lead to a greater fractional free volume and lower glass transition temperatures. Comparison of molecular relaxation times using the different characterization techniques demonstrates that there is strong coupling between motion of the main chain and the side groups, on which the dipoles reside. Intermolecular coupling between the main chains at the primary relaxation is shown in this work to be related to the nature of the side chains and resultant free volume, as are the temperature locations of local, secondary relaxations. A qualitative model describing the effect of regiochemistry on the motions and packing of these materials is also proposed. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1465-1481, 1998
    Additional Material: 13 Ill.
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  • 115
    Electronic Resource
    Electronic Resource
    Transition metal complexes of N-picolyl polyurethane (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1539-1546 
    Details
    ISSN: 0887-6266
    Keywords: nucleophilic substitution ; polyurethane metal complexes (PUC) ; coordination interaction ; phase separation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: N-Picolyl polyurethanes (PUPY) were synthesized by nucleophilic substitution. The blends of these polyurethanes with various of transition metal chlorides [cobalt(II), nickel(II), and copper(II)] were studied by spectroscopic and thermal analysis. Ultraviolet-visible and infrared spectroscopic evidence indicates that a tetrahedral cobalt(II) complex with two pendent picolyl groups in the first-shell coordination sphere of Co2+ is formed in a series of blends with different molar ratio (from 10/1 to 2/1) of picolyl groups to cobalt(II) ions. According to the result of Small-Angle X-ray Scattering (SAXS), Differential Scanning Calorimetry (DSC), and Dynamic Mechanical Thermal Analysis (DMTA), coordination interaction between ligands in hard segments and metal ions provides a driving force for phase separation. The coordination strength of pyridine with Ni2+ is stronger than Co2+ and Cu2+. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1539-1546, 1998
    Additional Material: 9 Ill.
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  • 116
    Electronic Resource
    Electronic Resource
    Electrically induced contraction of polypyrrole film in ambient air (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1591-1594 
    Details
    ISSN: 0887-6266
    Keywords: polypyrrole film ; contraction ; electric field ; desorption ; actuator ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No abstract.
    Additional Material: 4 Ill.
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  • 117
    Electronic Resource
    Electronic Resource
    Supramolecular structures of poly(γ-benzyl-L-glutamate) self-assembled on mica surface (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1567-1577 
    Details
    ISSN: 0887-6266
    Keywords: poly(γ-benzyl-L-glutamate) ; fibers ; atomic force microscopy ; dynamic light scattering ; random-coil solvents ; surface-induced rod-globular transition ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This article reports the results of structural studies of poly (γ-benzyl-L-glutamate) (PBLG) layers self-assembled from dilute solutions in organic solvents on mica surface. Polarized dynamic light scattering and atomic force microscopy were used to study polymer properties in solutions and on the surface. The hierarchy of self-assembly from PBLG solutions in different solvents was investigated as a function of polymer concentration and solvent polarity. We show that the surface-polymer interaction is suppressed in polar solvents that is interpreted in terms of suppressed charge-dipole interaction. The transformation of the PBLG surface structure occurs upon addition of different amounts of trifluoroacetic acid to polymer solution in dioxane. Rigid-rod PBLG molecules experience rod-globular transition while assembling on nonmodified mica from the very dilute solutions. A scheme is proposed describing different stages of PBLG fibrogenesis on a charged surface. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1567-1577, 1998
    Additional Material: 6 Ill.
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  • 118
    Electronic Resource
    Electronic Resource
    Combined relaxation study of poly(vinyl chloride) blends with chlorinated poly(ethylene), hydroxyl-terminated poly(butadiene), and ethylene-propylene-diene terpolymer (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1595-1608 
    Details
    ISSN: 0887-6266
    Keywords: PVC blends ; thermally stimulated current depolarization ; dynamic mechanical analysis ; physical quantities of relaxation transitions ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A number of blends based on suspension poly(vinyl chloride) and stabilizers with poly(ethylene) chlorinated in a fluidized-bed reactor containing 21.8% chlorine, hydroxyl-terminated poly(butadiene), and ethylene-propylene-diene terpolymer have been studied using such methods as thermally stimulated current depolarization and dynamic mechanical analysis. Some dielectric and thermodynamic parameters (τmax, τo, Ea, ΔH*, ΔSE*, ΔG*, μeff) have been determined. Blends containing randomly chlorinated poly(ethylene) exhibited dipole-dipole interactions between the macromolecules of poly(vinyl chloride) which decreased at the expense of the long sequences of nonchlorinated methylene groups. Simultaneously, an increased physical interaction between poly(vinyl chloride) and the additives was observed in blends containing chlorinated poly(ethylene) and/or hydroxyl-terminated poly(butadiene), and ethylene-propylene-diene terpolymer. On the basis of the data of dynamic mechanical analysis obtained a heterogeneous structure of the blends is suggested. The development of a boundary interfacial layer with a proper region of relaxation proves the formation of compatible structures between the components. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1595-1608, 1998
    Additional Material: 9 Ill.
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  • 119
    Electronic Resource
    Electronic Resource
    Monte carlo simulation of copolymerization by ester interchange reaction in miscible polyester blends (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1637-1645 
    Details
    ISSN: 0887-6266
    Keywords: ester interchange reaction ; Monte Carlo method ; copolymerization ; degree of randomness ; miscible polyester blend ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of reaction variables on the degree of randomness in copolymers formed by ester interchange reaction in miscible polyester melt blends were systematically investigated using a Monte Carlo method. Three reaction variables such as the molecular weight difference between two component polymers, the blend ratio, and the reaction ratio of end attack to bond flip, were particularly considered on the cubic lattice model. Ester interchange reactions were assumed to take place during reptational chain motions. It was found that the copolymerization was dependent upon the molecular weight difference and reaction ratio: As the molecular weight difference becomes smaller and when both end attack and bond flip reactions are involved simultaneously, the copolymerization is accelerated. However, the blend ratio does not affect the copolymerization process. This result is discussed in relation to the polymer chain conformation for the ester interchange reaction. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1637-1645, 1998
    Additional Material: 10 Ill.
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    Effects of CO2 conditioning on sorption, dilation, and transport properties of polysulfone (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1695-1702 
    Details
    ISSN: 0887-6266
    Keywords: sorption ; dilation ; diffusion ; conditioning effect ; glassy polymer ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Sorption, dilation, and diffusion behaviors were studied for the system of polysulfone/CO2 with regard to the effects of CO2 conditioning, i.e., exposure to high-pressure CO2. Concurrent measurements of solubility, dilation, and diffusivity were performed for polysulfone films before and after the conditioning at 25 and 50 atm. While the solubility and dilation were enhanced by the conditioning, the diffusivity appeared to be depressed. Results were analyzed on the basis of the dual-mode sorption model, with the assumption that the Henry's law dissolution was not affected by the conditioning. Consistent description was achieved then by attributing the changes to increased amount of Langmuir adsorption. The conditioning effect on the diffusivity, which had not been reported before based on CO2 sorption kinetics, suggests that the permeability of glassy polymers would not always be enhanced by the conditioning, but may also be decreased. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1695-1702, 1998
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    Strength of hydrogen bonding in the novolak-type phenolic resin blends (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1721-1729 
    Details
    ISSN: 0887-6266
    Keywords: phenolic ; miscibility ; hydrogen bonding ; PEO ; PEG ; PVA ; glass transition temperature ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The specific interaction strength of novolak-type phenolic resin blended with three similar polymers [i.e., poly(ethylene oxide) (PEO), poly(ethylene glycol) (PEG), and poly(vinyl alcohol) (PVA)] were characterized by means of glass transition temperature behavior and Fourier transform infrared (FTIR) spectroscopy. The interassociation formed within phenolic blends with the addition of a modifier not only overcomes the effect of self-association of the phenolic upon blending, but also increases the strength of phenolic blend. The strength of interassociation within the phenolic blend is the function of the hydrogen bonding group of a modifier, in increasing order, is phenolic/PVA, phenolic/PEG, and phenolic/PEO blend, corresponding to the result of “q” value in the Kwei equation. The FTIR result is in agreement with the inference of Tg behavior. In addition, the fact that the specific strength of hydrogen bonding of hydroxyl-hydroxyl is stronger than that of hydroxyl-ether can also be concluded. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1721-1729, 1998
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    Diffusion in gas separation membrane materials: A comparison and analysis of experimental characterization techniques (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1747-1755 
    Details
    ISSN: 0887-6266
    Keywords: kinetic sorption ; steady-state permeation/sorption ; polyimide ; carbon molecular sieve ; membrane separation processes ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Typically, materials with high-performance transport properties such as zeolites, carbon molecular sieves, or hyper rigid polymers are inherently difficult or impossible to characterize by steady-state membrane permeation experiments used for conventional polymers. Diffusion coefficients determined by transient sorption, a measurement easily performed on brittle media, are analyzed here and compared to those determined by steady-state permeation/sorption and transient permeation for a glassy polymer and a carbon molecular sieve. Average and local diffusion coefficients are extrapolated to zero upstream partial pressure to eliminate effects caused by concentration dependence. Good agreement between the techniques was observed for the glassy polymer. On the other hand, carbon molecular sieves, possessing a more complex morphology, exhibit a greater difference in diffusion coefficients determined by the various techniques. Nevertheless, comparison of the analysis techniques is shown to provide potentially valuable insights into the morphological features of such carbon molecular sieves. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1747-1755, 1998
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    Microphase separation and rheology of a semicrystalline poly(ether-ester) multiblock copolymer (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1795-1804 
    Details
    ISSN: 0887-6266
    Keywords: poly(ether-ester) ; rheology ; multiblock copolymer ; microphase separation transition ; crystallinity ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A microphase separation transition (MST) of a thermoplastic elastomer based on soft segments of poly(tetra methylene oxide) and hard crystalline segments of poly(tetra methylene terephthalate) has been studied by means of rheological measurements, differential scanning calorimetry (DSC), and wide-angle X-ray scattering (WAXS), showing that the MST is entirely caused by melting/crystallization, and that no separate segmental mixing/demixing transition is involved. DSC and WAXS measurements show that melting starts at 190°C, leading to crystal reorganization effects up to above 200°C, and that a gradual decrease in crystallinity occurs from below 210°C up to 224°C, above which temperature no crystals are left. Rheological measurements reveal a wide MST (207-224°C) upon heating, which coincides perfectly with the melting range. From this coincidence together with the Maxwell fluid behavior directly following the MST, it is concluded that melting leads to a one-phase liquid, and that no separate segmental mixing transition occurs. Similar results are obtained upon cooling, indicating that crystallization is the driving force for phase separation and that no separate segmental demixing step precedes crystallization. The wide MST implies a large processing window over which the rheological properties change from highly elastic, with a distinct yield stress, to normal pseudoplastic, enabling application in preparation of structured blends. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1795-1804, 1998
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    Influence of the plasticization on free volume in polyvinyl chloride (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1839-1845 
    Details
    ISSN: 0887-6266
    Keywords: positron annihilation ; polymers ; free volume ; plasticization of polymers ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Positron lifetime measurements in pure polyvinyl chloride (PVC) and in the plasticized PVC have been performed. Tricresyl phosphate was used as a plasticizer. Samples of the PVC were prepared with eight different plasticizer concentrations (from 0 to 35% of the plasticizer in the PVC). All of the measurements were performed in air at room temperature. A conventional fast-slow coincidence lifetime spectrometer was used for the measurements. Mean free volumes radii and fractional free volumes were calculated from the lifetime data. It has been found that the mean free volume radius is in the investigated region of the plasticizer concentrations, a linear function of the concentration of the tricresyl phosphate in the PVC. It seems that a polynomial fit can be used to describe the fractional free volume vs. the plasticizer concentration in the PVC. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1839-1845, 1998
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    PECVD of amorphous hydrogenated oxygenated nitrogenated carbon films (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1881-1888 
    Details
    ISSN: 0887-6266
    Keywords: actinometric optical emission spectrometry ; plasma/surface interactions ; nitrogenated plasma polymers ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An actinometric optical emission spectroscopy (AOES) study of the trends in the concentrations of the plasma species H, CH, CO, OH, and CN in film-producing glow discharges of mixtures of isopropanol and nitrogen was undertaken. Conventional AOES was used to obtain the trends in the plasma concentrations of these species as a function of the proportion of nitrogen in the feed, Rn. A dynamic variant of actinometry in which trends in the concentrations of plasma species are measured as a function of time following the cutting of one of the principal gas flows was also employed to investigate the relative importance of gas phase and plasma/polymer-surface interactions in the production of the species of interest. Each of the above-mentioned species is produced, to some degree, by plasma/polymer-surface reactions. As revealed by transmission infrared spectroscopy, the films deposited contain C—H, C=O, and O—H groups. For Rn 〉 0, the films become nitrogenated, with both N—H and C≡N groups being present. As revealed by transmission ultraviolet-visible spectroscopy, both the optical gap and the refractive index of the deposited films decrease as Rn is increased. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1881-1888, 1998
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    Structure and morphology of nylon 2 4 lamellar crystals: Comparison with polypeptides and relationship with other nylons (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2401-2412 
    Details
    ISSN: 0887-6266
    Keywords: nylon 2 4 ; chain folding ; lamellar crystals ; structure and morphology ; crystallization ; electron microscopy ; Brill transformation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chain-folded lamellar crystals of nylon 2 4 have been prepared from dilute solution by addition of poor solvent. Two crystal structures are observed at room temperature: a monoclinic form I, precipitated at elevated temperature, and a less-defined, orthorhombic form II, precipitated at room temperature. The unit cell parameters for both forms are similar to those reported for its isomer, nylon 3. Nylon 2 4 form II is a liquid-crystal-like or disordered phase, consisting of hydrogen-bonded sheets in poor register in the hydrogen bond direction. Form I crystals have two characteristic interchain spacings of 0.41 nm and 0.39 nm at room temperature and on heating, exhibit a structural transformation and a Brill temperature (250°C) characteristic of many other even-even nylons. Nylon 2 4 is a member of the nylon 2 Y and nylon 2N 2(N+1) families, and the form I crystals show behavior commensurate with both. We propose they contain a proportion of intersheet hydrogen bonds at room temperature, similar to that for the nylon 2 Y family, and the short dimethylene alkane segments mean that the structure consists of hydrogen-bonded a-sheets, with an amide unit in each fold, similar to that of nylon 4 6. The fold geometry and sheet structure is compared with chain-folded apβ-sheet polypeptides and nylon 3. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2401-2412, 1998
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    Characterization of novel optically active conjugated polyarylenes and poly(aryleneethnylene)s by a combination of off-line static and dynamic light scattering with gel permeation chromatography (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2615-2622 
    Details
    ISSN: 0887-6266
    Keywords: optically active polymers ; gel permeation chromatography ; laser light scattering ; GPC calibration ; rodlike conformation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By combining the offline static and dynamic laser light scattering (LLS) and gel permeation chromatography (GPC) results of a broadly distributed polymer sample, we were able to characterize a series of chiral binaphthyl-based polyarylenes and poly(aryleneethnylene)s in THF at 25°C. For each of the samples, we obtained not only the weight-average molar mass Mw, the second virial coefficient A2 and the z-average translational diffusion coefficient 〈D〉, but also two calibrations: V = A + Blog(M) and D = kD M-αD, where V, D, and M are the elution volume, the translational diffusion coefficient and the molar mass for monodisperse polymer chains, respectively, and A, B, kD, and αD are four calibration constants. Using these calibrations, we estimated the molar mass distributions of these novel polymers. We showed that using polystyrene to calibrate the GPC columns could lead to a smaller Mw. Our results indicate that all the polymers studied have a rigid chain conformation in THF at 25°C and the introduction of the  - NO2 groups into the monomer can greatly promote the polymer solubility in THF.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2615-2622, 1998
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    Influence of the polymer structure on the achievement of polar orientation in high glass transition temperature nonlinear optical polyimides by photo-assisted poling (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1669-1677 
    Details
    ISSN: 0887-6266
    Keywords: photo-assisted poling ; polymer dynamics ; polymer structure ; nonlinear optical polyimides ; high glass transition temperature ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We have used combinations of light, heat, and electrostatic fields to investigate the orientation of nonlinear azo-chromophores chemically incorporated into high glass transition temperature (Tg) polyimides. A number of nonlinear optical polyimides have been synthesized in which the interaction between the nonlinear optical chromophore and the polymer main chain was systematically altered to determine to what extent this steric interaction influences the orientation of the nonlinear chromophore. Chromophores in polymers may be oriented by a number of methods: (a) polarized light at room temperature (i.e., photo-induced orientation or PIO), (b) polarized light and electric fields (i.e., photo-assisted poling or PAP) at temperatures ranging from room temperature to the polymer Tg, and (c) electric fields at Tg (thermal poling). While thermal poling and PIO are usually possible, PAP depends strongly on the molecular structure of the polymer. Previously we have shown that PIO can be accomplished at room temperature in a system where the nonlinear chromophore is embedded into the polyimide main chain via the donor substituent, and this orientation can only be thermally erased at temperatures approaching Tg. In this article we show that, whereas photoisomerization can efficiently depole donor-embedded polyimides in a matter of few minutes at room temperature, PAP does not induce any polar order. This behavior is in marked contrast to a structurally related, side-chain, nonlinear polyimide, in which the azo chromophore is tethered via a flexible linkage to the polymer backbone. In this case some PAP occurs even at room temperature, while no PAP is observed for a donor-embedded system with a similar Tg. We suggest that the orientation during PAP below Tg in the side-chain polyimide is primarily due to the movement of the azo side chains, and there is a very little coupling of this motion to the main chain. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1669-1677, 1998
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    Temperature and concentration dependence of diffusion coefficients in ethylene-propylene-diene copolymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1713-1719 
    Details
    ISSN: 0887-6266
    Keywords: polymer ; diffusion ; free-volume theory ; inverse gas chromatography ; gravimetric sorption ; ethylene-propylene-diene ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Self-diffusion and partition coefficients were measured for two commercial ethylene-propylene-diene copolymers (EPDM) and five solvents at infinite dilution using inverse gas chromatography. Mutual diffusion coefficients for solvents in EPDM also were measured for finite concentration using gravimetric sorption for three of the solvents. From the inverse gas chromatography experimental values for self-diffusion coefficients were obtained. Free-volume parameters were obtained through regression of the self-diffusion coefficient as a function of temperature. Mutual diffusion coefficients as a function of concentration were predicted using free volume theory and compared with experimental data obtained using gravimetric sorption. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1713-1719, 1998
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    Multiple melting endotherms in isothermally melt-crystallized poly(butylene terephthalate) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1757-1767 
    Details
    ISSN: 0887-6266
    Keywords: poly(butylene terephthalate) ; differential scanning calorimetry (DSC) ; isothermal melt crystallization ; primary crystallization ; secondary crystallization ; recrystallization ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The melting behavior of poly(butylene terephthalate) crystallized isothermally for various times was examined using differential scanning calorimetry. After short crystallization times, the DSC analysis gave two melting peaks, but after longer times, the analysis gave three peaks. The latter triplet of DSC peaks can be denoted as low, middle, and high, starting with the lowest temperature endotherm. The DSC peaks were simulated using a measured recrystallization rate and behavior for PBT and an assumed initial melting point distribution. The low and middle peaks represent the original melting peaks arising from isothermal crystallization. The high melting peak arises from recrystallization during the DSC heating scan. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1757-1767, 1998
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    Pressure and volume dependence of thermal conductivity and isothermal bulk modulus up to 1 GPa for poly(isobutylene) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1781-1792 
    Details
    ISSN: 0887-6266
    Keywords: bulk modulus ; equation of state ; heat capacity ; high-pressure ; poly(isobutylene) ; thermal conductivity ; transient hot-wire method ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermal conductivity λ and heat capacity per unit volume ρcp of poly(isobutylene)s, one 2.8 in weight average molecular weight and one 85 kg mol-1 in viscosity average molecular weight (PIB-2800 and PIB-85000), have been measured in the temperature range 170-450 K at pressures up to 2 GPa using the transient hot-wire method. At 297 K and atmospheric pressure, λ = 0.115 W m-1 K-1 for PIB-2800 and λ = 0.120 W m-1 K-1 for PIB-85000. The bulk modulus BT has been measured in the temperature range 170-297 K up to 1 GPa. At atmospheric pressure, the room temperature bulk moduli BT are 2.0 GPa for PIB-2800 and 2.5 GPa for PIB-85000 with dBT/dp = 10 for both. These data were used to calculate the volume dependence of λ, \documentclass{article}\pagestyle{empty}\begin{document}$$ g = - \left({{\partial\lambda/\lambda}}\over{{\partial V/V}}\right)_{T}. $$\end{document} At room temperature and atmospheric pressure (liquid phase) we find g = 3.4 for PIB-2800 and g = 3.9 for PIB-85000, but g depends strongly on temperature for both molecular weights. The difference in g between the glassy state and liquid phase is small and just outside the inaccuracy of g of about 8%. The best predictions for g are given by the theoretical model of Horrocks and McLaughlin. We have found that PIB exhibits two relaxations, where one is associated with the glass transition. The value for dTg/dp at atmospheric pressure (for the main glass transition) is about 0.21 K MPa-1 for both molecular weights. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1781-1792, 1998
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    Effects of the polyamide molecular structure on the performance of reverse osmosis membranes (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1821-1830 
    Details
    ISSN: 0887-6266
    Keywords: reverse osmosis ; poly(aminostyrene) ; benzenediamines ; acyl chlorides ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thin-film composite reverse osmosis membranes of polyamides were prepared by interfacial polymerization. Various benzenediamines and poly(aminostyrene) were interfacially reacted with various acyl chlorides to prepare a skin layer of composite membranes. Among the membranes prepared from the structural isomeric monomers of benzenediamines and acyl chlorides, i.e., the same chemical composition but different in the position of functional groups on the aromatic ring, the membrane with the best salt rejection was obtained when the reacting groups forming amide are located at the same position on the aromatic ring. Membranes prepared by interfacially reacting various diamines with trimesoyl chloride revealed that the salt rejection depends on the linear chain structure of polyamides and network formed by crosslinking. Membranes obtained by interfacial polymerization of poly(aminostyrene) with trimesoyl chloride showed higher water flux but lower salt rejection than those obtained by interfacial polymerization of various benzenediamines with trimesoyl chloride. Membranes obtained here showed the typical trade-off behavior between salt rejection and water flux. However, membranes prepared by interfacially reacting trimesoyl chloride with a mixture of poly(aminostyrene) and m-phenylenediamine or a mixture of poly(aminostyrene), m-phenylenediamine, and diaminobenzoic acid showed a performance advantage over usual membranes, i.e., a large positive deviation from the usual trade-off trend. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1821-1830, 1998
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    Thin film deposition from plasmas of tetramethylsilane-helium-argon mixtures with oxygen and with nitrogen (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1873-1879 
    Details
    ISSN: 0887-6266
    Keywords: plasma-enhanced chemical vapor deposition ; actinometric optical emission spectroscopy ; tetramethylsilane ; nitrogen ; oxygen ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Films were produced by plasma enhanced chemical vapor deposition (PECVD) of tetramethylsilane (TMS)-helium-argon mixtures with either oxygen or nitrogen in a vacuum system fed with radiofrequency power. Actinometric optical emission spectroscopy was used to determine trends in the concentrations of plasma species of interest (H, CH, O, CO, and CN) as a function of the ratio of the inorganic reactive gas (oxygen or nitrogen) to the monomer (TMS) in the system feed. As the ratio of oxygen to TMS in the feed is increased, the degree of oxygenation of the deposited material, as revealed by transmission infrared spectroscopy, is also increased. Similarly, the degree of nitrogenation of the films increases with increasing nitrogen to monomer ratio in the feed. Strong correlations exist between the plasma concentrations of the above-mentioned plasma species and film structure and composition. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1873-1879, 1998
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    Electron paramagnetic resonance studies on oxidative polymerization mechanism of furan derivatives (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1901-1910 
    Details
    ISSN: 0887-6266
    Keywords: oxidative polymerization ; furan ; 3-methylfuran ; 2,2′,5′,2″-terfuran ; electron paramagnetic resonance ; ab initio calculation ; polymerization mechanism ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The oxidative polymerization of furan, 3-methylfuran and 2,2′,5′,2″-terfuran, induced by iodine in organic solvents having different donicity, was investigated by time-resolved electron paramagnetic resonance (EPR) spectroscopy. The reaction was monitored starting from the onset of the process and radical species arising from the monomers in early stages of the polymerization reaction were detected. The comparison between experimental and theoretical hyperfine coupling constants, obtained by simulated EPR spectra and theoretical ab initio calculations, respectively, allowed one to structurally characterize the above radical species, thus enabling mechanistic conclusions about oxidative coupling. Moreover, the analysis of the time evolution of EPR spectrum during the oxidative polymerization process was used for evaluating the relative amount of localized and mobile radical species along the polymer backbone, thus getting preliminary information about conjugation extent and electroconducting properties of the final material. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1901-1910, 1998
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    Particulate growth in phase-separated polymer blends (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2191-2196 
    Details
    ISSN: 0887-6266
    Keywords: polymer blends ; coalescence ; Ostwald ripening ; scaling law ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Particle coarsening was investigated in polymer blends containing a minor phase volume of 23% produced by compositional quenching. The scaling exponents for three binary blends (polystyrene/polybutadiene, polystyrene/polyisoprene, and polystyrene/S-B random copolymer) were in reasonable agreement with the expected value of 0.33. The scaling exponent for a ternary blend containing an amphiphile (polystyrene/polybutadiene/S-B block copolymer) was substantially lower at 0.14. The particle size distributions for all the blends were broader than the self-similar distribution expected for Ostwald ripening and became increasingly broad with time. These distributions fit a two parameter coalescence model in which the probability of coalescence is proportional to the particle diameter. However, Ostwald ripening appears to make some contribution, particularly at early times. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2191-2196, 1998
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    Interface, morphology, and the rheological properties of polymethylmethacrylate/impact modifier blends (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2623-2634 
    Details
    ISSN: 0887-6266
    Keywords: interface ; surface tension ; rheological ; morphology ; polymethylmethacrylate ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Impact modifiers with grafted PMMA shell are used to modify polymethylmethacrylate matrix. The composition of the shell is chosen to enhance the interactions at the modifier/matrix interface and to obtain good dispersion of the impact modifier in order to optimize impact strength of the blend. The degree of interactions at the interface is characterized by the interfacial region where the chains of the matrix mix with those of the shell of the modifier. The deviation of the measured viscoelastic behavior of these blends from that predicted by the emulsion models has been attributed to the formation of the network structure due to the association of matrix chains with the shell of the modifier. It is expected that the network structure will decrease with increasing frequency and, as such, the effective volume of the particle is frequency dependent. This study uses the emulsion models to estimate the larger effective volume of the particle and, therefore, the extent of interaction at the interface. In the blends of this study it can be shown that at low modifier levels the solvent swelling of the modifier shell results in stronger interactions with the matrix; this effect is negated by the aggregation of particles at higher modifier loadings. The interaction of core modifier with the PMMA matrix seems to be similar to that of the core-shell modifier. This would not be expected from the calculated interfacial thickness of approximately 4 nm. It is, therefore, proposed that during melt-processing the core modifier surface was altered due to grafting of the matrix PMMA chains during melt-blending to (BA/St) copolymer of the core modifier thus reducing the interfacial tension. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2623-2634, 1998
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    Anionic copolymerization of [60]fullerene with styrene initiated by sodium naphthalene (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2653-2663 
    Details
    ISSN: 0887-6266
    Keywords: [60]fullerene ; styrene ; anionic copolymerization ; structural characterization ; sodium naphthalene ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The novel C60-styrene copolymers with different C60 contents were prepared in sodium naphthalene-initiated anionic polymerization reactions. Like the pure polystyrene, these copolymers exhibited the high solvency in many common organic solvents, even for the copolymer with high C60 content. In the polymerization process of C60 with styrene an important side reaction, i.e., reaction of C60 with sodium naphthalene, would occur simultaneously, whereas crosslinking reaction may be negligible. 13C-NMR results provided an evidence that C60 was incorporated covalently into the polystyrene backbone. In contrast to pure polystyrene, the TGA spectrum of copolymer containing ∼ 13% of C60 shows two plateaus. The polystyrene chain segment in copolymer decomposed first at 300-400°C. Then the fullerene units reptured from the corresponding polystyrene fragments attached directly to the C60 cores at 500-638°C. XRD evidence indicates that the degree of order of polymers increases with the fullerene content increased in terms of crystallography. Incorporation of C60 into polystyrene results in the formation of new crystal gratings or crystallization phases. In addition, it was also found that [60]fullerene and its polyanion salts [C60n-(M+)n, M = Li, Na] cannot be used to initiate the anionic polymerization of some monomers such as acrylonitrile and styrene, etc.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2653-2663, 1998
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    Microphase separation in RIM polyureas as studied by solid-state NMR (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 693-703 
    Details
    ISSN: 0887-6266
    Keywords: phase separation ; NMR spectroscopy ; block copolymers ; reaction injection molding ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The microphase separation (MPS) in polyureas based on methylene diphenyl diisocyanate (MDI) hard segment, diethyltoluenediamine chain extender, and amino-terminated polypropylene glycol soft segment prepared by reaction injection molding (RIM) was studied by advanced solid-state NMR spectroscopy. Incomplete microphase separation leads to the presence of mobilized hard segments dispersed in the soft segment domains as well as immobilized soft segments residing in the hard domains. This is detected by 1H-NMR spectra recorded under spinning at the magic angle (MAS) as well as two-dimensional wide-line separation (WISE) NMR spectra. The sizes of the various domains as well as the interfaces between them are quantified by spin diffusion measurements. In this way the impact of annealing, method of polymerization, and hard segment content on MPS is studied. Whereas annealing at temperatures up to 170°C results in improving the MPS, major changes are observed after annealing at higher temperatures (190°C), where the system changes from “soft-in-hard” to “hard-in-soft” behavior. The MPS decreases with increasing hard segment content. The highest MPS is observed for solution polymerized samples. The various NMR experiments clearly reveal the nonequilibrium nature of RIM systems. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 693-703, 1998
    Additional Material: 13 Ill.
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  • 139
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    The specific viscosity of partially hydrolyzed polyacrylamide solutions: Effects of degree of hydrolysis, molecular weight, solvent quality and temperature (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 743-753 
    Details
    ISSN: 0887-6266
    Keywords: polyacrylamides ; specific viscosity ; polyelectrolyte solutions ; light scattering ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dependences of the specific viscosity of several polyelectrolytes on polyelectrolyte concentration, salt concentration or solution ionic strength, solution pH value, solvent quality, and solution temperature were systematically investigated. We found that the specific viscosity obeys a more general relation: ηsp = Acp2/(cp + 2cs)3/2 + B, where ηsp is the polyelectrolyte specific viscosity, cp and cs are polymer and salt concentrations, respectively. The prefactor A depends critically on chain size, solvent quality, and temperature in qualitative agreement with the theory proposed by Rabin et al. The intercept B is nonzero or less than zero in polyelectrolyte solutions with low ionic strength. When a sufficient amount of salt has been added, B is reduced to zero and we recover the Rabin et al.'s relation. The physical interpretation for the intercept B is that it represents the inverse of the strength of electrostatic interaction between a polyion and counterions, in quantitative agreement with the well-known emperical Fuoss's relation. Furthermore, the existence of nonzero B allows us to calculate the condition for the maximum in the reduced viscosity-polymer concentration curve in a polyelectrolyte solution system without salt. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 743-753, 1998
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    Study of interaction between polyethylene glycol and chitosan by viscosity method (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1275-1281 
    Details
    ISSN: 0887-6266
    Keywords: chitosan ; polyethylene glycol polyblend ; intermolecular interaction ; viscometry ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular structures of polyethylene glycol (PEG) and chitosan (CS) are illustrated as follows: 1CS2PEG\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm HO} \hbox{--} {\rm CH}_2 {\rm CH}_2 \rlap{--} ({\rm O} \hbox{--} {\rm CH}_2 {\rm CH}_2 \rlap{--} {\rm O} \hbox{--} {\rm CH}_2 {\rm CH}_2 \hbox{--} {\rm OH} $$\end{document} The intermolecular interactions between these two polymers were studied by viscometry with a thermodynamic parameter α, which was first proposed by Sun et al. The weight additive rule of the intrinsic viscosity of polyblend relating to the values of each polymeric constituent was attested to with PEG/CS polyblend. The calculation formula of Huggins coefficient for polyblend, km, was theoretically deduced, and a very simple expression of α was obtained. First, the values of α for PEG/CS blends with different PEG molecular weight were estimated from the experimental viscosity data of the polyblends with different mixed ratio. According to these values of α, it can be predicted that an attractive interaction exists between the molecule of PEG and that of CS. Second, the viscosity of CS was measured in pseudo-solvents (PEG dissolved in 0.01N sodium chloride aqueous solution) with different PEG concentrations. From these viscosity data, the values of cross Huggins coefficient are calculated to be all larger than the values of the Huggins coefficient both for CS and for PEG. On the revised α criterion, the dissimilar molecular interaction in PEG/CS polyblend is demonstrated to be attractive too. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1275-1281, 1998
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  • 141
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    Swelling of polyacrylamide gels in polyacrylamide solutions (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1313-1320 
    Details
    ISSN: 0887-6266
    Keywords: swelling ; polyacrylamide gels ; swelling in polymer solutions ; polymer-polymer interaction parameter ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Swelling behavior of polyacrylamide (PAAm) and polyacrylamide-co-polyacrylic acid (PAAm-co-PAAc) gels was investigated in aqueous solutions of monodisperse PAAms with molecular weights (Mw) ranging from 1.5 × 103 to 5 × 106 g/mol. The volume of the gels decreases as the PAAm concentration in the external solution increases. This decrease becomes more pronounced as the molecular weight of PAAm increases. The classical Flory-Huggins (FH) theory correctly predicts the swelling behavior of nonionic PAAm gels in PAAm solutions. The polymer-polymer interaction parameter χ23 was found to decrease as the molecular weight of PAAm increases. The swelling behavior of PAAm-co-PAAc gels in PAAm solutions deviates from the predictions of the FH theory. This is probably due to the change of the ionization degree of AAc units depending on the polymer concentration in the external solution. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1313-1320, 1998
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  • 142
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    Phase separation induced by a chain polymerization: Polysulfone-modified epoxy/anhydride systems (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1349-1359 
    Details
    ISSN: 0887-6266
    Keywords: reaction-induced phase separation ; polysulfone-epoxy blends ; epoxy-anhydride networks ; polysulfone-modified epoxies ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The reaction-induced phase separation in a blend of a commercial polysulfone (PSu) with diepoxide-cyclic anhydride monomers, was studied. The diepoxide was based on diglycidylether of bisphenol A (DGEBA) and the hardener was methyl tetrahydrophthalic anhydride (MTHPA), used in stoichiometric proportion. Benzyldimethylamine (BDMA) was used as initiator. PSu had no influence on the polymerization kinetics, the gel conversion, and the overall heat of reaction per epoxy equivalent. A kinetic model including initiation, propagation, and termination steps was used to estimate the distribution of linear and branched species in the first stages of the chain-wise copolymerization. This distribution, together with the PSu distribution, were taken into account in a thermodynamic model of the blend. The interaction parameter was fitted from experimental determinations of conversions at the start of phase separation, obtained under different conditions. The thermodynamic model was used to explain the complex morphologies developed in materials containing different PSu concentrations as well as their dynamic mechanical response. The shift in glass transition temperatures was explained by the fractionation of different species during the phase separation process. Phase inversion produced a significant decrease of the elastic modulus in the glassy state and a thermoplastic-like behavior of the material in the rubbery region. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1349-1359, 1998
    Additional Material: 11 Ill.
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    The effect of network architecture on the thermal and mechanical behavior of epoxy resins (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1371-1382 
    Details
    ISSN: 0887-6266
    Keywords: epoxy resins ; thermosets ; glass transition ; yield behavior ; fracture toughness ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of crosslink functionality (fc), molecular weight between crosslinks (Mc), and chain stiffness display on the thermal and mechanical behavior of epoxy networks are determined. Both fc and Mc are controlled by blending different functionality amines with a difunctional epoxy resin. Chain stiffness is controlled by changing the chemical structure of the various amines. In agreement with rubber elasticity theory, the rubbery moduli are dependent on fc and Mc, but independent of chain stiffness. The glassy moduli and secondary relaxations of these networks are relatively independent of fc, Mc, and chain stiffness. However, the glass transition temperatures (Tg) of these networks are dependent on all three structural variables. This trend is consistent with free volume theory and entropic theories of Tg. fc, Mc, and chain stiffness control the yield strength of these networks in a manner similar to that of Tg and is the result that both properties involve flow or relaxation processes. Fracture toughness, as measured by the critical stress intensity factor (KIc), revealed that fc and Mc are both critical parameters. The fracture behavior is the result of the fracture toughness being controlled by the ability of the network to yield in front of the crack tip. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1371-1382, 1998
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  • 144
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    Photoconductivity of a polyimide with an alicyclic diamine: Charge carrier photogeneration in the mixed layer packing arrangement (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1433-1442 
    Details
    ISSN: 0887-6266
    Keywords: photoconductivity ; charge carrier ; fluorescence ; curing effect ; molecular aggregation ; polyimides with alicyclic diamines ; intermolecular interaction ; mixed layer packing ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Photoconduction mechanism of a polyimide with an alicyclic diamine, PI(PMDA/DCHM), prepared from pyromellitic dianhydride (PMDA) and 4,4′-diaminodicyclohexylmethane (DCHM) was investigated. Its UV absorption spectra, fluorescence spectra, photoconductivity, and annealing effects on the photocurrent generation were measured and compared to those of CPD, N,N′-dicyclohexylpyromellitic diimide, and PI(PMDA/DMDHM) prepared from PMDA and 3,3′-dimethyl-4,4′-diaminodicyclohexylmethane (DMDHM). Photoconductivity of PI(PMDA/DCHM) depends upon the degree of molecular packing between polymer backbones. PI(PMDA/DMDHM) has no photoconductivity, probably due to a barrier to their intermolecular packing by the existence of two methyl substituents. Photoconductivity of PI(PMDA/DCHM) would be the result of the weak intermolecular interaction formed by mixed layer packing arrangement between pyromellitic moiety of one polymer backbone and N-cyclohexyl ring of another one in the ground state. Radiation absorption of this weak intermolecular interaction immediately forms a charge-transfer complex in the excited state and produces radical cation and anion charge carriers, which lead to the photoconductivity in the bulk polyimide film of PI(PMDA/DCHM). © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1433-1442, 1998
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    Structure of interpenetrating polymer networks (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1507-1512 
    Details
    ISSN: 0887-6266
    Keywords: interpenetrating polymer networks ; gelation ; phase separation ; kinetics ; poly(carbonate-urethane)/polyvinyl pyridine ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A possible model for the formation of interpenetrating polymer networks is suggested. Phase separation is assumed to be faster than gelation. This implies that domains rich in either component grow first until late stages of spinodal decomposition. In these domains, short linear chains are crosslinked, leading to large branched macromolecules. Growth of the domains is slowed down by the presence of crosslinked polymers. It is assumed that it is stopped when the sizes of the domains and of the branched macromolecules are comparable. The resulting domains are significantly larger than the average distance between crosslinks. These results are supported by recent neutron scattering results on a poly(carbonate-urethane)/polyvinyl pyridine interpenetrating network. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1507-1512, 1998
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  • 146
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    The temperature dependence of the local free volume in polyethylene and polytetrafluoroethylene: A positron lifetime study (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1513-1528 
    Details
    ISSN: 0887-6266
    Keywords: free volume ; thermal expansion ; positron lifetime measurements ; semicrystalline polymers ; polyethylene ; polytetrafluoroethylene ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Positron lifetime measurements, performed in the temperature range 80-300 K, are reported for polyethylene (PE) and polytetrafluoroethylene (PTFE). The lifetime spectra have been analyzed using the data processing routines LIFSPECFIT and MELT. Two long-lived components appear, which are attributed to pick-off annihilation of ortho-positronium in crystalline regions and at holes in the amorphous phase. The ortho-positronium lifetimes, τ3 and τ4, are used to estimate the crystalline packing density and the size of local free volumes in the crystalline and amorphous phases. The interstitial free volume in the crystals exhibits a weak linear increase with the temperature which is attributed to thermal expansion of the crystal unit cell. In the amorphous phase, the hole volume varies between 0.053 and 0.188 nm3 (PE) and between 0.152 and 0.372 nm3 (PTFE). Its temperature variation may be fitted by two straight lines, the intersection of which is used to estimate a glass transition temperature of Tg = 195 K for both PE and PTFE. The slopes of the free volume in the glassy and crystalline phases with the temperature correlate well with each other. The coefficients of thermal expansion of the hole volume are compared with the macroscopic volume change below and above the glass transition. From this comparison a fractional hole volume at Tg of 4.5 (PE) and 5.7% (PTFE) and a number of 0.73 (PE) and 0.36 (PTFE) × 1027 holes/m3 is estimated. Finally, it is found that the intensity of o-Ps annihilation in crystals shows a different temperature dependence to that in the amorphous phase. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1513-1528, 1998
    Additional Material: 11 Ill.
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    Segmental dynamics of poly(styrene-b-2-vinylpyridine) in bulk and at the surface/air interface (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1609-1616 
    Details
    ISSN: 0887-6266
    Keywords: polymer-surface interactions ; deuterium NMR ; block copolymers ; polymer micelles ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Anionically polymerized poly(α-deuterostyrene) and poly(β-deuterostyrene-b-2-vinylpyridine) (DSVP), selectively deuterated on the styrene backbone, were studied using deuterium wide-line NMR in bulk and adsorbed on silica and alumina. Changes in the segmental dynamics of the bulk and adsorbed polymers were inferred via changes in the NMR line shape with temperature. The DSVP bulk sample, which consisted of micellar aggregrates with a 2-vinylpyridine core, was more rigid than the homopolystyrene of a similar molecular weight. A significant change in mobility occurred at 20°C higher in the DSVP bulk sample than it did in homopolystyrene. The DSVP-adsorbed sample showed more restrictive mobility than bulk DSVP. The spectra of the adsorbed samples contained “rigid” Pake patterns with considerable intensity at temperatures where the collapse of the Pake pattern for the DSVP bulk sample was observed. DSVP bound to the silica surface was found to have a mobility similar to the same copolymer on alumina. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1609-1616, 1998
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  • 148
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    Thermodynamic properties of novolac-type phenolic resin blended with poly(ethylene oxide) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1647-1655 
    Details
    ISSN: 0887-6266
    Keywords: thermodynamics ; phenolic ; PEO ; polymer blend ; PCAM ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermodynamic properties of novolac type phenolic resin blended with poly(ethylene oxide) (PEO) were investigated by the Painter-Coleman association model (PCAM). Equilibrium constants and enthalpy corresponding to the interaction between phenolic and poly(ethylene oxide) were calculated from the Fourier transform infrared spectroscopy of low molecular weight analogues in dilute solutions. The association parameters of the model compounds are transferred to the corresponding polymers, to predict the Gibbs free energy, phase behavior, and the degree of hydrogen bonding in the polymer blend. The heat capacity (CP) and the excess heat capacity (ΔCP) are used to verify the validity of PCAM model on predicting the thermodynamics properties of phenolic/PEO blend. It is found that the hydrogen bonding interaction dominates at moderate temperatures, which is outweighed by the dispersion force at higher temperature or high PEO compositions. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1647-1655, 1998
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    Hydrocarbon polymers containing six-membered rings in the main chain. Microstructure and properties of poly(1,3-cyclohexadiene) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1657-1668 
    Details
    ISSN: 0887-6266
    Keywords: microstructure ; properties ; poly(1,3-cyclohexadiene) ; living anionic polymerization ; hydrogenated derivatives ; triblock copolymer ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relationship between the microstructure and the properties of poly(1,3-cyclohexadiene)s, obtained by living anionic polymerization with an alkyllithium/amine system, and their hydrogenated derivatives are reported. The 1,2-bond/1,4-bond molar ratio of poly(1,3-cyclohexadiene) was determined by measuring 2D-NMR with the H—H COSY method. The glass transition temperature of poly(1,3-cyclohexadiene) was found to rise with an increase in the ratio of 1,2-bonds to 1,4-bonds or with an increase of the number average molecular weight. The 1,2-bond of the polymer chain gives a high flexural strength and heat distortion temperature. Hydrogenated poly(1,3-cyclohexadiene) has the highest Tg (231°C) among all hydrocarbon polymers ever reported. 1,3-Cyclohexadiene-butadiene-1,3-cyclohexadiene triblock copolymer and 1,3-cyclohexadiene-styrene-1,3-cyclohexadiene triblock copolymer have high heat resistance and high mechanical strength. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1657-1668, 1998
    Additional Material: 7 Ill.
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    Probe diffusion in homogeneous diblock copolymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1739-1746 
    Details
    ISSN: 0887-6266
    Keywords: block copolymers ; molecular diffusion ; Forced Rayleigh scattering ; free volume ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Forced Rayleigh scattering was used to investigate the diffusion of a photoreactive dye molecule in two homogeneous poly(styrene-b-isoprene) (SI) diblock copolymers with overall molecular weights of approximately 2000. Although diffusion rates were intermediate to TTI transport in homopolymer polystyrene (PS) and polyisoprene (PI), system dynamics appear to be largely dictated in each case by the PI block. The size of the polymer jumping unit, on the other hand, is evaluated from a free-volume analysis of the data, and is found to be governed predominantly by the PS component of the copolymer. The mechanism for tracer diffusion in low-molecular-weight block copolymers appears analogous to transport in a high molecular weight SI diblock copolymer (Mn = 13,600) that has been solvated sufficiently in toluene to be microstructurally disordered. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1739-1746, 1998
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    Erratum (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1793-1793 
    Details
    ISSN: 0887-6266
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No abstract.
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    Polymer blends of polyamide-6 (PA6) and poly(phenylene ether) (PPE) compatibilized by a multifunctional epoxy coupler (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1805-1819 
    Details
    ISSN: 0887-6266
    Keywords: polymer blend ; PA6 ; PPE ; epoxy ; reactive compatibilizer ; coupling agent ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A tetrafunctional epoxy monomer, N,N,N′-N′-tetraglycidyl-4,4′-diaminodiphenyl methane (TGDDM), has demonstrated to be a highly efficient reactive compatibilizer in compatibilizing the immiscible and incompatible polymer blends of polyamide-6 (PA6) and poly(2,6-dimethyl-1,4-phenylene ether) (PPE). This epoxy coupler can react with both PA6 and PPE to form various PA6-co-TGDDM-co-PPE mixed copolymers. These interfacially formed PA6-co-TGDDM-co-PPE copolymers tend to anchor along the interface to reduce the interfacial tension and result in finer phase domains and enhanced interfacial adhesion. A simple one-step melt blending has demonstrated to be more efficient in producing a better compatibilized PA6/PPE blend than a two-step sequential blending. The mechanical property improvement of the compatibilized blend over the uncompatibilized counterpart is very drastic, by considering the addition of a very small amount, a few fractions of 1%, of this epoxy coupling agent. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1805-1819, 1998
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    Electrical transport in 0-3 epoxy resin-barium titanate-carbon black polymer composites (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1847-1856 
    Details
    ISSN: 0887-6266
    Keywords: electrical transport ; dielectric properties ; barium titanate ; carbon black ; epoxy resin ; relaxation processes ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Conductivity and dielectric constant of a three-component 0-3 composite of epoxy resin-barium titanate-carbon black (0-3 composites are systems in which the filler is in the form of 0-dimensional (point-like, disperse) particles in a three-dimensional polymeric matrix1) have been investigated both at DC and the frequency range of 20-106 c/s. The effect of barium titanate concentration on percolation threshold, critical indices and the mechanism of conduction has been examined. An attempt was made to describe the electrical properties of composites with models originally developed for two-component systems' dielectric-conductor. With increasing barium titanate concentration the agreement of experimentally found frequency dependencies of conductivity and dielectric constant with models based on Debye's equation was found to degrade. An adequate description of electrical properties of composites' dielectric-ferroelectric-conductor should be based on the Havriliak-Negami equation. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1847-1856, 1998
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    Cocontinuity and phase inversion in HDPE/PS blends: Influence of interfacial modification and elasticity (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1889-1899 
    Details
    ISSN: 0887-6266
    Keywords: polymer ; blend ; cocontinuity ; phase inversion ; interface ; morphology ; elasticity ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In this work the level of continuity and cocontinuity for blends of HDPE/PS prepared on a twin-screw extruder have been studied by both morphology and dissolution studies. Addition of SEBS as an interfacial modifier results in a shift of the percolation threshold for dispersed PS to higher concentrations. The region of phase inversion, however, is maintained at 70% PS. The shift in the percolation threshold to higher values is related to reduced elongation of the PS dispersed phase after interfacial compatibilization. These results indicate that an interfacial modifier significantly influences percolation phenomena without shifting the region of phase inversion. Models based on viscosity ratio have failed to predict the region of phase inversion in this study. Elastic effects are shown to be able to describe the basic tendencies. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1889-1899, 1998
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    Interpretation of the observed influence of mesophase structures on the β-relaxation in side chain liquid crystal polymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1927-1934 
    Details
    ISSN: 0887-6266
    Keywords: side chain liquid crystal polymers ; β-relaxation ; rotation of mesogenic units ; compensation law ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A strong dependence of the rotational dynamics of the mesogenic units (β-relaxation) on the order of the mesophase was found in sidechain liquid crystal polymers. The preexponential frequency factor, \documentclass{article}\pagestyle{empty}\begin{document}$ f_{\beta \infty }^* $\end{document} and the activation energy \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm E}_{\alpha \beta }^{\rm *} $\end{document} of the β-relaxation rate both increase significantly (i.e., obeying a compensation law) with increasing order of the mesophase which is accompanied by a decrease of the mean lateral mesogenic distance. In this work, we show how these experimental results can be interpreted in a quantitative manner by using the general results of the coupling model for cooperative motions. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1927-1934, 1998
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    Miscibility and transesterification in blends of liquid crystalline copolyesters and polyarylate (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1959-1969 
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    ISSN: 0887-6266
    Keywords: miscibility ; transesterification ; kinetics ; polyarylate ; liquid crystalline copolyesters ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of poly(oxybenzoate-p-ethylene terephthalate) (POB-PET) and polyarylate were confirmed to be a partially miscible system by differential scanning calorimetry. When 60/40 POB-PET/PAr blend was annealed at high temperature (above 270°C) for several minutes, the ester-ester interchange (transesterification) in the blend took place immediately, as evidenced by Fourier Transformed infrared analyses. The analysis of the blend annealed at 290°C by 1H-13C nuclear magnetic resonance disclosed that there were four new diads appearing in 15 min and an additional one produced in 60 min during the heat treatment. The miscibility between POB-PET and polyarylate increased with the mol concentration of these new diads judging from differential scanning calorimetry. The evolution of the concentration of the diad ethylene glycol-isophthalate during the annealing can be described by a second-order reaction. The activation energy of forming the diad ethylene glycol-isophthalate was 26.5 kcal/mol, and the preexponential factor for the transesterification reaction is 3.7 × 108 min-1. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1959-1969, 1998
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    Small-angle scattering of polarized light. VI. Sphere doublets at rest and during shear (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2005-2013 
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    ISSN: 0887-6266
    Keywords: sphere doublets ; light scattering ; suspension ; flow ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polarized or depolarized light scattering by well-defined monodispersed sphere doublets is investigated. Two configurations of doublets are studied. In the first (at rest) the doublets are randomly oriented in a plane, in the second the doublets are oriented in a preferred direction. This is achieved by submitting a suspension of doublets to a shear flow. The scattering patterns are compared to two theoretical predictions based on simplified geometries. In the first approach, the doublet is approximated by two interpenetrating spheres scattering independently, whereas in the second, an ellipsoid geometry is used. A good qualitative comparison is obtained. However, the HV and VH patterns of a randomly dispersed suspension are not similar. The observation of the flow of a doublet suspension in shear shows that the doublets are spiraling around the vorticity axis. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2005-2013, 1998
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    Spherulite boundary strengthening concept for toughening polypropylene (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2047-2056 
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    ISSN: 0887-6266
    Keywords: polypropylene ; spherulite ; cocrystallization ; lamellae ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: During spherulitic crystallization of polymers, there is a tendency for low molecular weight and other less crystallizable entities to be rejected from the body of the spherulites. This rejection process causes a segregation of these species to those areas where spherulites impinge. As a result of this segregation, lamellar and spherulite boundaries have a tendency to become weak, often resulting in premature mechanical failure. The objective of this work, anthropomorphically speaking, is to develop a melt miscible blend system in which a propylene copolymer “fools” a polypropylene homopolymer into rejecting the copolymer to the spherulite boundaries as an impurity. However, once the copolymer arrives at these boundaries, the copolymer subsequently connects adjacent spherulites through cocrystallization of the propylene copolymer segments. It was found that addition of either a random ethylene-propylene copolymer or an isotactic-atactic block copolymer was able to yield the desired effect. Cocrystallization was confirmed by calorimetry, and segregation of copolymer and subsequent reinforcement at the spherulite boundaries was directly observed microscopically. Using this approach, toughness was increased with little loss in stiffness. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2047-2056, 1998
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    Network development during shear-thickening in semidilute solutions of gently solubilized starches (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2085-2093 
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    ISSN: 0887-6266
    Keywords: starch ; shear-thickening ; semidilute solution ; viscoelastic properties ; oscillatory shear flow ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The shear-thickening behavior of semidilute waxy maize (WM) starch solutions (90/10 DMSO/water) exhibit much of the behavior of classical nonlinear viscoelasticity. Small-amplitude oscillatory shear experiments were used to investigate the network structure formed during the shear-thickening regime. The solution viscoelastic properties of WM starch prior to the shear-thickening region could be described by the GLV model. The macromolecules behave as random coils with a longest relaxation time of 0.58 ± 0.03 s. For WM starch the observed shear-thickening region creates a stable, highly entangled network which resembles the behavior found in solutions in the concentrated regime. The longest relaxation time for the entangled solution is estimated to be 1.4 s. Semidilute solutions of normal maize (NM) starch in 90/10 DMSO/water do not exhibit a shear-thickening regime. The oscillatory shear data obtained before and after a thixotropic loop experiment were identical. The semidilute solution conformational dynamics of NM starch indicate some degree of rigidity in one of the components that constitute NM starch which might be associated with the helical structure obtained by amylose in DMSO. © 1998 John Wiley & Sons, Inc. This article is a US Government work, and, as such, is in the public domain in the United States of America. J Polym Sci B: Polym Phys 36: 2085-2093, 1998
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    Investigation of adhesion hysteresis in poly(dimethylsiloxane) networks using the JKR technique (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2129-2139 
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    ISSN: 0887-6266
    Keywords: adhesion hysteresis ; poly(dimethylsiloxane) ; JKR technique ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The JKR technique was used to determine the source and nature of the adhesion hysteresis present in modified poly(dimethylsiloxane) (PDMS) networks. As controlled excess amounts of the tetrafunctional crosslinker were added to the networks, the adhesion hysteresis increased. It was found that by poisoning the catalyst with a thiol the hysteresis could be significantly lowered, and completely removed in some cases. We believe that the adhesion hysteresis in this system stems from a complexation between the excess crosslinker and the catalyst. We found that the work of adhesion in this case is a function of the unloading rate. The unloading rate dependence of this chemical adhesion hysteresis was attributed to the rate of bond dissociation. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2129-2139, 1998
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    Clustering and percolation effects in microcrystalline starch-reinforced thermoplastic (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2211-2224 
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    ISSN: 0887-6266
    Keywords: starch ; mechanical properties ; percolation ; clustering ; diffusion ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The use of starch microcrystals as biodegradable particulate filler is evaluated by processing composite materials with a weight fraction of starch ranging from 0 to 60%. In a previous work [Macromolecules, 29, 7624] the preparation technique of a colloidal suspension of hydrolyzed starch and the processing of composite materials by freeze drying and molding a mixture of aqueous suspensions of starch microcrystals and synthetic polymer matrix were presented. Starch microcrystals with dimensions of a few nanometers were obtained from potatoes' starch granules, and it was found that this filler produces a great reinforcing effect, especially at a temperature higher than Tg of the synthetic matrix. Classical models for polymers containing nearly spherical particles based on a mean field approach could not explain this reinforcing effect. The morphology of these nanocomposite systems is discussed in light of aggregate formation and percolation concepts. The sorption behavior of these materials is also performed. Starch is a hygroscopic material, and it is found that the composites absorb more water, as the starch content is higher. The diffusion coefficient of the penetrant is predicted from modified mechanical three branch series-parallel model based on a percolation approach. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2211-2224, 1998
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    Moisture-absorption, dielectric relaxation, and thermal conductivity studies of polymer composites (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2259-2265 
    Details
    ISSN: 0887-6266
    Keywords: polymer composite ; moisture-absorption ; dielectric loss ; thermal conductivity ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the search for new packaging materials for the electrical/electronics industry, three types of polymer composites have been studied. Silicone/boron nitride powders, polyurethane/alumina powders, and polyurethane/carbon fibers have all been synthesized to study the moisture-absorption kinetics, thermal conductivities, and the dielectric loss spectra under various levels of humidity. The water uptake data indicate that water molecules are absorbed not only by the polymer matrix, but also by the interfaces introduced by the fillers. For all materials, the dielectric relaxation spectroscopy shows the presence of a peak in the 175-200 K range, which is largely due to absorbed water. The silicone/boron nitride samples absorbed the least amount of moisture. Incorporating this result with the thermal conductivity data of the three types of polymer composites, it is concluded that silicone polymers embedded with boron nitride can best serve as the coating for the electronic devices that require heat dissipation and moisture resistance, in addition to electrical insulation. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2259-2265, 1998
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    Examination of miscibility at molecular level of poly(hydroxyether of bisphenol A)/poly(N-vinyl pyrrolidone) blends by cross-polarization/magic angle spinning 13C nuclear magnetic resonance spectroscopy (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2291-2300 
    Details
    ISSN: 0887-6266
    Keywords: poly(hydroxyether of bisphenol A) ; poly(N-vinylpyrrolidone) ; polymer miscibility ; polymer blend ; solid-state (NMR) ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The miscibility of poly(hydroxyether of bisphenol A) (phenoxy) and poly(N-vinyl pyrrolidone) (PVP) was investigated by differential scanning calorimetry (DSC) and high-resolution solid-state nuclear magnetic resonance (NMR) techniques. The DSC studies showed that the phenoxy/PVP blends have a single, composition-dependent glass transition temperature (Tg). The S-shaped Tg-composition curve of the phenoxy/PVP blends was reported, which is indicative of the strong intermolecular hydrogen-bonding interactions. To examine the miscibility of the system at molecular level, high-resolution solid-state 13C nuclear magnetic resonance (NMR) technique was employed. Upon adding phenoxy to system, the chemical shift of carbonyl carbon resonance of PVP was observed to shift downfield by 1.6 ppm in the 13C cross-polarization (CP)/magic angle spinning (MAS) together with the high-power dipolar decoupling (DD) spectra when the concentration of phenoxy is 90 wt %. The observation was responsible for the formation of intermolecular hydrogen bonding. The proton spin-lattice relaxation time T1(H) and the proton spin-lattice relaxation time in the rotating frame T1ρ(H) were measured as a function of the blend composition. The T1(H) result was in good agreement with the thermal analysis, i.e., the blends are completely homogeneous on the scale of 20 ∼ 30 nm. The six results of T1ρ(H) further indicated that the blends were homogeneous on the scale of 40 ∼ 50Å. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2291-2300, 1998
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    Construction of ternary phase diagrams in nonsolvent/solvent/PMMA systems (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 607-615 
    Details
    ISSN: 0887-6266
    Keywords: ternary phase diagram ; binodal curve ; Flory-Huggins theory ; interaction parameter ; membrane formation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In this work, the ternary phase diagrams in three nonsolvent/solvent/PMMA systems (n-hexane/n-butyl acetate/PMMA, water/acetone/PMMA, and n-hexane/acetone/PMMA) were constructed by theoretical calculation and experimental measurement. Binodal curves were calculated by using the Flory-Huggins theory for three-component systems and measured by titrating the PMMA solution with nonsolvent until the onset of turbidity. By using concentration-dependent nonsolvent/solvent and solvent/PMMA interaction parameters and constant nonsolvent/PMMA interaction parameters, good agreement has been obtained between the calculation and the measurement. The values of nonsolvent/solvent interaction parameters were taken from the literature sources, and the values of solvent/PMMA and nonsolvent/PMMA interaction parameters were measured by vapor sorption and swelling equilibrium, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 607-615, 1998
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    Track overlap regime in ion-irradiated PMMA (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 655-664 
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    ISSN: 0887-6266
    Keywords: PMMA ; ion beam ; scission ; G value ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Chemical and physical effects induced by bombardment of nearly monodisperse Poly(methyl methacrylate) (PMMA) with energetic ions (He+) at 200 keV have been studied. Bond scission is the main results of low fluence ion irradiation but, at high fluence there is a regime transition of PMMA from positive tone resist behavior to negative tone. The ion-induced chemical reactions in the macromolecular film give rise to gas evolution and chemical changes in the solid residue. The gas formed during the bombardment has been studied by means of a mass spectrometer, while the solid polymer has been characterized by measuring the molecular weight distribution (MWD) and the absorption coefficient in the Near Infrared (NIR), visible, and ultraviolet regions. X-ray Photoelectron Spectroscopy (XPS) has been performed to learn what happens at the surface of the polymer after bombardment. The main result of these studies is that at fluence higher than 1013 cm-2 both chemical and physical effects follow a nonlinear behavior due to the transition from a single-track regime to a track overlap regime. This transition is explained in terms of progressive chemical change of the irradiated polymer from the pristine chemical structure to a new one depleted of the ester pendent groups. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 655-664, 1998
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    Inorganic/organic host-guest materials: Surface and interclay reactions of styrene with copper(II)-exchanged hectorite (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 673-679 
    Details
    ISSN: 0887-6266
    Keywords: scanning force microscopy ; hectorite ; polystyrene ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Many important layered silicate-polymer nanocomposite materials may be synthesized using an in-situ polymerization process. Using this technique, organic monomers are intercalated into the interlayer regions of the hosts, where subsequent polymerization may then occur. In this paper, we report on the in-situ polymerization of styrene in Cu(II)-exchanged hectorite thin films. Scanning force microscopy (SFM) images of the polymer surface reveal that the surface polystyrene is generally aggregated into groups of elongated strands. SFM imaging of the interclay regions, in conjunction with X-ray diffraction (XRD) and electron spin resonance (ESR) data, indicates that approximately 20-30% of these regions contain polystyrene, with minimal reduction in the majority of Cu2+ sites observed. XRD data shows little or no intercalation of the monomer into the true intergallery regions. Instead, the polymer likely forms in intercrystallite or planar defect regions. In addition, two distinct phases of polymeric material are found within these defect regions, a highly polymerized polystyrene in addition to a polystyrene form exhibiting greater material stiffness. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 673-679, 1998
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    Role and effect of dopant ion on sorption-induced motion of polypyrrole films (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 2635-2642 
    Details
    ISSN: 0887-6266
    Keywords: polypyrrole film ; bending ; strain ; sorption isotherm ; diffusion ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The sorption-induced bending and recovery motion of PPy films containing different dopant ions have been investigated, and the interaction between water vapor and PPy was studied from sorption isotherms and kinetics. It was found that the PPy/BF4 film exhibited the most rapid motion, and the initial speeds of bending and recovery motion were 7.9 and 5.9 mm s-1, respectively. The linear expansion coefficient of the film increased in order of PPy/DBS, PPy/TsO, PPy/ClO4, and PPy/BF4, which is consistent with the packing density of the PPy chains (φPPy). The dual-mode sorption model applied to the isothermal sorption of water vapor to the PPy demonstrated that the Langmuir's capacity constant increased in the same order with the φPPy, while the Henry's law constant was nearly constant. The sorption kinetics obeyed Fickian despite the dimensional change of the films, and the PPy/BF4 film had the largest diffusion coefficient of 3.13 × 10-8 cm2 s-1. The experimental results indicated that the kind of dopant ion was crucial to the thermodynamics and kinetics of sorption, and the quick and intensive bending motion of PPy/BF4 films was attributed to the fast diffusion of water vapor, which caused the large dimensional change of the film.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2635-2642, 1998
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    Effect of permeation temperature on permeation and separation of a benzene/cyclohexane mixture through liquid-crystalline polymer membranes (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 281-288 
    Details
    ISSN: 0887-6266
    Keywords: side-chain liquid-crystalline polymer membrane ; pervaporation ; benzene/cyclohexane mixture ; state-transformation ; benzene permselectivity ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When a benzene/cyclohexane mixture of 10 wt % benzene was permeated through side-chain liquid-crystalline polymer (LCP) membranes by pervaporation at various temperatures, the permeation rate increased with increasing permeation temperature. The LCP membranes also exhibited a benzene permselectivity. The permselectivity for the benzene/cyclohexane mixture through the LCP membrane was different in the glassy, liquid-crystalline, and isotropic states. The LCP membrane had different apparent activation energies for permeation at each state. LCP membrane in the liquid-crystalline state had the highest apparent activation energy of the three states. Results suggest that the benzene permselectivity was influenced by changes in the LCP membrane structure, i.e., a state-transformation. It was found that a balance of the orientation of mesogenic groups and the flexibility of the siloxane chains was very important for benzene permselectivity. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 281-288, 1998
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    Dispersion polymerization of styrene in ethanol-water media: Monomer partitioning behavior and locus of polymerization (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 325-335 
    Details
    ISSN: 0887-6266
    Keywords: dispersion polymerization ; styrene ; water-ethanol mixtures ; partitioning behavior ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simulation model has been developed to predict the partitioning behavior of styrene in dispersion polymerization in ethanol-water mixtures. The composition of both the continuous phase and the dispersed phase are quantitatively estimated throughout the polymerization process. The presence of water in the system causes a considerable increase of the styrene partitioning in favor of the particles. Thus, at 70°C and for an initial composition of ethanol/water/styrene = 63.3/26.9/9.8, the concentration of styrene in the particles is about 4.8 times higher than that in the serum instead of about one in pure ethanol. The higher the polymerization temperature, the lower the styrene concentration in the particles; the higher the initial styrene concentration, the higher the styrene concentration in the particles, whereas the partition coefficient is not largely effected. In contrast, neither the interfacial tension nor the final particle size do significantly alter the simulation results. The predicted data from this model have been successfully applied to clarify the mechanisms involved in dispersion polymerization, in terms of stabilization and of kinetic events. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 325-335, 1998
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    Study of bundle formation during crystallization in polymer blends (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 873-888 
    Details
    ISSN: 0887-6266
    Keywords: crystallization ; polymer blends ; pattern formation ; numerical simulation ; syndiotactic polystyrene ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The development of texture which exists in polymer spherulites grown from single phase melts containing an appreciable amount of noncrystallizable material was investigated. This texture generally consists of lamellar bundles separated by amorphous regions, both of which are typically 0.1-1 μm thick. A space-time finite element model previously developed by us was used to simulate the growth of a group of polymer lamellae. The model determines the impurity concentration field in the melt surrounding the growing lamellae and tracks the growth of each lamella. Important variables are the initial melt concentration of noncrystallizable material, the mass diffusion coefficient of noncrystallizable species, lamellar thickness, long period, and the rate of molecular attachment at the growth front. Under certain conditions, bundles did indeed develop during the simulations. These results were used to predict bundle thicknesses. The predictions of bundle texture were compared to actual textures observed in blends of syndiotactic and atactic polystyrene. It was found both experimentally and numerically that bundle thickness was a strong function of crystallization temperature and a relatively weak function of both the initial composition of noncrystallizable species and the degree of crystallinity of the lamellar stack. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 873-888, 1998
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    Cooperative motions in PVC studied by thermally stimulated currents: Comparison with A.C. dielectric derivative analysis (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 913-918 
    Details
    ISSN: 0887-6266
    Keywords: glass transition ; thermally stimulated currents (TSC) ; relaxation ; PVC ; dielectric ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The thermally stimulated current-thermal sampling (TSC-TS) technique was used to study the broadened glass transition in conventional “atactic” poly(vinyl chloride), PVC. The activated parameters obtained from the TSC-TS data, mainly the apparent activation energy (Ea), characterize the breadth of glass transitions in a very sensitive way. These results are compared with those values of Ea obtained from the literature, using a recently proposed method of analyzing a.c. dielectric constants and their derivatives, over the temperature range of -100-130°C. Both techniques detect weak cooperative glass transition-like relaxations well below the main glass transition of ca. 80°C. As is the case with “atactic” PMMA, the data suggest that compositional heterogeneity related to a small fraction of predominantly isotactic sequences contribute to the broad glass transition extending ca. 60°C below the main glass transition in atactic PVC. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 913-918, 1998
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    Cross-linking of poly[1-(trimethylsilyl)-1-propyne] membranes using bis(aryl azides) (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 959-968 
    Details
    ISSN: 0887-6266
    Keywords: PTMSP ; cross-linking ; membranes ; permeability ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cross-linkable poly[1-(trimethylsilyl)-1-propyne] (PTMSP) films were cast from toluene solutions containing PTMSP and either 4,4′-diazidobenzophenone or 4,4′-(hexafluoroisopropylidene)diphenyl azide. The composite films were clear and homogeneous and were cross-linked by UV irradiation at room temperature or thermal annealing at 180°C. Low levels of the bis(aryl azide) (1-5 wt %) were effective in rendering the films insoluble in toluene and THF, both good solvents for PTMSP. The process is simple and effective, and thus PTMSP can be readily converted to mechanically stable membranes with permeabilities and separation factors comparable or higher than those of poly(dimethylsiloxane). The films were characterized by measuring their density, their permeability toward O2 and N2, and their spectroscopic properties. Compared to PTMSP, films containing bis(aryl azide) cross-linkers had lower permeabilities and higher separation factors, consistent with a reduction in free volume. When the films were cross-linked photochemically, the permeabilities declined further and the separation factor increased. Films cross-linked thermally had permeabilities comparable to their PTMSP/azide precursors, and density and swelling measurements suggest that higher free volumes are obtained in thermally cross-linked films. All films stored in air suffered from a slow decline in permeability which may reflect slow surface oxidation of the films. When stored in vacuum, cross-linked films were stable and showed no loss in permeability, but the permeability of uncross-linked PTMSP films stored under the same conditions fell to 70% of their original value in 1 month. We attribute the permeability decline to densification accelerated by impurities and solvents. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 959-968, 1998
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    Smectic networks obtained from twin LC epoxy monomers - mechanical deformation of the smectic networks (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 31-38 
    Details
    ISSN: 0887-6266
    Keywords: liquid crystals ; thermosets ; smectic epoxy ; nematic ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Deformation experiments were carried out for densely crosslinked smectic-like networks obtained from diepoxy monomers with twin mesogen architecture. For the initially unoriented smectic networks, the network could be aligned up to an orientation parameter of 0.35 by applying 8 MPa of external stress in the rubbery regime. X-ray diffraction measurements revealed that the deformed smectic network possesses both smectic-A like and smectic-C like structure. It is thought that after extension domains initially oriented parallel to the external stress displayed a smectic-A-like structure, whereas domains initially tilted with respect to the tensile direction showed a stress-induced smectic-C like structure. A smectic network oriented under a.c. electric fields with an orientation parameter of 0.4 had a smectic-A like structure and possessed linear elasticity in the rubbery regime. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 31-38, 1998
    Additional Material: 11 Ill.
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    Copolymer composition-dependent light transmission of polymer/liquid crystals composite films (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 55-64 
    Details
    ISSN: 0887-6266
    Keywords: PDLC ; polarization ; angular discrimination ; copolymer ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Electrooptic responses (voltage and angular-dependent transmittance) of polymer/liquid crystal composite films with H, V, and unpolarized lights have been studied based on a nematic liquid crystal (Ro-5921) and four types of homopolymers and copolymers from ethyl methacrylate and styrene with different compositions. In this way, the index ratio of the polymer (np) to the ordinary refractive index of liquid crystal (no)(np/no) has been varied systematically, and the effect of the index ratio on viewing angle, applied voltage, response times, and transient response have been investigated. With increasing styrene content in the copolymer, droplet size increased, threshold (Vth) and saturation (Vsat) voltage, and rise time decreased. With np ≲ no, maximum transmittance occurred at normal incidence, regardless of the type of polarization. On the contrary with np 〉 no, V-polarization gave a peak in the transmittance-voltage curve, and transmittance overshot upon removal of the field, and these were interpreted in terms of effective refractive index and two-step relaxations. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 55-64, 1998
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    A quantitative model for the specific volume of polymer-diluent mixtures in the glassy state (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1037-1050 
    Details
    ISSN: 0887-6266
    Keywords: polymer glasses ; glass transition ; diluents ; antiplasticization ; mixtures ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A mathematical model to describe the specific volume of glassy mixtures of a polymer and a low molecular weight diluent or additive is presented. The model is based on understandable physical assumptions and relies on parameters that can be determined experimentally or estimated from methods available in the literature. The predictions of the model show good agreement with the experimental data for mixtures of four polymers with diluents that in the pure state are liquid, glassy, or crystalline. The observed negative departure from volume additivity, as defined by simple additivity of the specific volume of the pure glassy polymer and the pure amorphous diluent, is the result of the relaxation of the excess volume of the glassy mixture relative to the equilibrium state caused by mixing two components with different glass transition temperatures. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1037-1050, 1998
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    Photopolymerization of nematic liquid crystal monomers for structural applications: Linear viscoelastic behavior and cure effects (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1081-1089 
    Details
    ISSN: 0887-6266
    Keywords: liquid crystals ; acrylate ; photopolymer network ; dynamic mechanical analysis ; infrared dichroism ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This article is concerned with molecular orientation in liquid crystal (LC) monomers and the retention of orientation in crosslinked network polymers formed from them by photopolymerization. This is of importance because anisotropic mechanical and physical properties can be beneficial in certain structural applications. To this end, linear viscoelastic behavior of liquid crystal photo-monomers was investigated with dynamic mechanical analysis, and molecular order was studied by infrared dichroism measured with Fourier transform infrared spectroscopy. Although the order parameter of the monomer could vary from 0.45 to 0.70, depending on temperature, the order parameters of the polymer samples varied only from 0.50 to 0.62 and depended on polymerization temperature and extent of cure. The mechanical anisotropy was found to be a complicated phenomenon that depended not only on the molecular order, but also on other factors such as free volume and network structure. The difference in the elastic modulus parallel and perpendicular to the alignment direction was as high as a factor of two in the glassy state, and a factor of three above Tg. In addition, different amounts of mechanical anisotropy could be induced by varying the cure conditions. Finally, different postcuring schemes could cause variations in mechanical behavior by advancing cure or by inducing secondary reactions. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1081-1089, 1998
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    Chain-packing effects in the thermodynamics of polymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 3001-3005 
    Details
    ISSN: 0887-6266
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
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    Scaling and structural properties of a polymer in a simple solvent: A study based on integral equations (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 3025-3033 
    Details
    ISSN: 0887-6266
    Keywords: integral equations for polymers ; solvent effects ; polymer conformation ; scaling properties ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We present a statistical mechanical theory for polymer-solvent systems based on integral equations derived from the polymer Kirkwood hierarchy. Integral equations for pair monomer-monomer, monomer-solvent, and solvent-solvent correlation functions yield polymer-solvent distribution, chain conformation in three dimensions, and scaling properties associated with polymer swell and collapse in athermal, good, and poor solvents. Variation of polymer properties with solvent density and solvent quality is evaluated for chains having up to 100 bonds. In good solvents, the scaling exponent v has a constant value of about 0.61 at different solvent densities computed. For the athermal solvent case, the gyration radius and scaling exponent decrease with solvent density. In a poor solvent, the chain size scales as Nv with the value of the exponent being about 0.3, compared with the mean field value of ⅓. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3025-3033, 1998
    Additional Material: 5 Ill.
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    The phase behavior of tetramethyl bisphenol-A polyarylate/aliphatic polyester blends (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 201-212 
    Details
    ISSN: 0887-6266
    Keywords: tetramethyl bisphenol-A polyarylate ; aliphatic polyester ; blend ; miscibility ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The phase behavior of blends of tetramethyl bisphenol-A polyarylate (TMPAr) with various linear aliphatic polyesters characterized by the ratio of aliphatic carbons to ester groups in the repeating unit, CH2/COO = 3 ∼ 9, was examined by differential scanning calorimetry and dynamic mechanical analysis. TMPAr/aliphatic polyester blends prepared by solvent casting were found to be miscible when the CH2/COO ratio of aliphatic polyesters was larger than 4 and up to 9. The thermodynamic interaction parameter, B for the miscible blends was determined by the analysis of the depression of the melting point of polyester using the Hoffman-Weeks method. From the analysis of the heat of mixing data using a binary interaction model, it was concluded that strong unfavorable intramolecular interaction exists between the —CH2— and —COO— units in aliphatic polyesters and that four substituted methyl groups produces more favorable effects on the miscibility TMPAr with aliphatic polyesters. © 1998 John Wiley & Sons, Inc. J Polym Sci 36: 201-212, 1998
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    The response of entangled polymer solutions to step changes of shear rate: Signatures of segmental stretch? (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 265-280 
    Details
    ISSN: 0887-6266
    Keywords: entangled polymer solution ; double-step strain rate ; flow birefringence ; tube model ; segmental stretch ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Experiments measuring the orientation angle and birefringence in startup and double-step strain rate flows were conducted on a 3.0 wt % 8.42 × 106 molecular weight polystyrene solution in a Couette flow cell. A phase-modulated flow birefringence apparatus was used to noninvasively probe the sample. Upon startup from rest, the orientation angle undershoots its final steady-state value, as seen by earlier investigators. When the shear rate undergoes a step increase from one nonzero value to another, the amplitude of this undershoot is decreased. However, a more significant effect is a shorter time scale overshoot in the orientation angle that is highly counterintuitive in the sense that an increase of shear rate initially produces a rotation of chain segments away from the flow direction. Similarly, a step decrease in shear rate yields an initial transient rotation toward the flow direction. In both cases, the height of the peaks depends upon the magnitude of the shear rate jump, and the width of the peaks is a function of the final shear rate. The longer time transients in the startup and step increase experiments reflect an apparent change in the relaxation time for segment orientation, which we tentatively attribute to a combination of tube dilation and convective constraint release. The shorter time scale over- and undershoots in the orientation angle appear to be qualitatively explained by considering the differences in extension or contraction of segments along the polymer chain. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 265-280, 1998
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    Dielectric spectroscopy and calorimetry during postcuring of a linear chain polymer thermoset formed from a diepoxide and cyclohexylamine, and the nature of the products (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 303-318 
    Details
    ISSN: 0887-6266
    Keywords: dielectrics ; calorimetry ; linear-chain thermoset ; postcuring ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric permittivity and loss spectra of an equimolar liquid mixture of diglycidyl ether of bisphenol-A and cyclohexylamine have been studied during the liquid's isothermal polymerization or curing in separate experiments at different temperatures and thereafter during the postcuring, both on rate-heating and isothermally. The spectra obtained during the growth of the linear chain polymer during the curing and postcuring show the evolution of an intermediate relaxation process whose position in the frequency plane remains relatively insensitive to the decrease in the configurational entropy during the postcuring, but whose strength increases. Postcuring ceases to occur once the calorimetric glass-liquid transition temperature of 345 K, corresponding to the ultimately formed polymeric state, has been reached. The increase in the number of covalent bonds, n, formed during curing and postcuring decreased the equilibrium dielectric permittivity, εs, and increased the characteristic relaxation time, τ0, for all curing and postcuring conditions. For a fixed temperature and n, (dεs/dT) and (dτ0/dT), as well as the values εs and τ0 of the ultimately formed state of the polymers differ significantly when the thermal history of polymerization differs. The slow dynamics in the glass-liquid transition region were analyzed in terms of the enthalpy relaxation and fictive temperature concepts. The distribution of relaxation times for these dynamics correspond to the stretched exponential parameter of 0.6, which is significantly greater than 0.39 determined for the dielectric α-relaxation spectra measured at a temperature 30 K higher. The enthalpy relaxation involves a narrower distribution of intermolecular barriers than dielectric relaxation. The results also show that the recently proposed method for determining the gelation time from the plots of the imaginary component of electrical impedance lacks scientific merit. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 303-318, 1998
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    Analysis of the potentiometric titration curves within the framework of the theory of the “neighbor effect” (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 931-936 
    Details
    ISSN: 0887-6266
    Keywords: potentiometric titration ; mathematical simulation ; neighbor effect ; interpolymer complexes ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The theory of the “neighbor effect” was applied for the description of the potentiometric titration curves of polyelectrolytes. Satisfactory results for poly(acrylic acid) were obtained by considering the effect of the two (at the right and at the left) nearest neighbors on the state of the monomeric unit in the limits of triads. The developed method was used for the determination of the degree of linkage of acidic groups in solutions of the interpolymer complexes. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 931-936, 1998
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    Positron annihilation lifetime studies of free volume in a polymer electrolyte PEO complexed with NH4I (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 969-976 
    Details
    ISSN: 0887-6266
    Keywords: positron annihilation ; conducting polymers ; free volume in polymers ; electrical conductivity in polymer electrolytes ; analysis of positron lifetime spectra ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Positron lifetime spectroscopy has been applied to study the temperature dependence of free-volume properties in a solvent-free polymer-salt complex polyethylene oxide (PEO) doped with ammonium iodide (NH4I, with NH4+ ≈ 0.076) in the temperature range of 298-353 K. The observed lifetime spectra were resolved into three components and the longest lifetime, τ3, was associated with the pick-off annihilation of ortho-positronium (o-Ps) trapped by the free volume. The lifetime component, τ3, and its intensity, I3, both showed a significant variation with temperature, which followed a different course in the heating and cooling cycle. Changes in the temperature coefficient of τ3 and I3 were observed at T ≈ 328 K, the melting point of the sample. This behaviour is correlated to the temperature variation of the electrical conductivity. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 969-976, 1998
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    High speed melt spinning of poly(L-lactic acid) filaments (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1005-1012 
    Details
    ISSN: 0887-6266
    Keywords: polylactide ; melt spinning ; fiber formation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Poly(L-lactic acid) filaments were prepared by high speed melt spinning at take-up velocities up to 5000 m/min. The crystallinity, birefringence, tensile strength, Young's modulus and yield strength all exhibit maxima at take-up velocities between 2000 and 3000 m/min. The boiling water shrinkage exhibits a minimum in this range. The maximum tensile strength of the as-spun filaments was 385 MPa and the maximum modulus was 6 GPa. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1005-1012, 1998
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    Compatibilizing effect of isocyanate functional group on polyethylene terephthalate/low density polyethylene blends (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 447-453 
    Details
    ISSN: 0887-6266
    Keywords: polyethylene terephthalate ; low density polyethylene ; isocyanate functional group ; compatibility ; crystallization ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: To evaluate the compatibilizing effects of isocyanate (NCO) functional group on the polyethylene terephthalate/low density polyethylene (PET/LDPE) blends, LDPE grafted with 2-hydroxyethyl methacrylate-isophorone diisocyanate (LDPE-g-HI) was prepared and blended with PET. The chemical reaction occurred during the melt blending in the PET/LDPE-g-HI blends was confirmed by the result of IR spectra. In the light of the blend morphology, the dispersions of the PET/LDPE-g-HI blends were very fine over the PET/LDPE blends. DSC thermograms indicated that PET microdispersions produced by the slow cooling of the PET/LDPE-g-HI blends were largely amorphous, with low crystallinity, due to the chemical bonding. The tensile strengths of the PET/LDPE-g-HI blends were higher than those of the PET/LDPE blends having a poor adhesion. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 447-453, 1998
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    Conformational changes of a polyelectrolyte in mixtures of water and acetone (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1107-1114 
    Details
    ISSN: 0887-6266
    Keywords: polyelectrolytes ; conformational change ; water-acetone mixture ; viscosity and conductivity ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Samples of a polyelectrolyte poly(methacryloylethyl trimethylammonium methylsulfate), PMETMMS, with molar masses Mw = 22-25 × 106 were examined with viscosity, static light scattering, and conductivity measurements in a water-acetone solvent. Because acetone is a nonsolvent for this polymer the measurements were performed to determine the influence of the solvent composition, the polymer concentration, and the presence of added ions on the conformation of the polyelectrolyte in mixed solvents. The possible influence of a hydrodynamic field on the polymer conformation was also studied. The viscosity of the polymer solutions as a function of polymer concentration, as well as of the solvent composition, was studied using a broad range of shear rates. When the mass fraction of acetone in the solvent, γ, is below 0.5, the solutions show a usual polyelectrolyte behavior. When γ ≥ 0.80, the polymer adopts a compact conformation. This is observed as a decrease of the radius of gyration, Rg, second virial coefficient, A2, the viscosity, and also as a change in the conductivity of the solution. The change in the polymer conformation may be induced also by dilution. When 0.60 ≤ γ 〈 0.80, a gradual decrease in the polymer concentration leads to a sudden decrease of the reduced viscosity, which indicates a decrease in the particle size. The values of Mw measured by static light scattering were constant in all experiments. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1107-1114, 1998
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    Birefringence of dilute PS solutions in transient elongational flow (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1483-1500 
    Details
    ISSN: 0887-6266
    Keywords: dilute polystyrene solution ; flow birefringence ; transient elongational flow ; local orientation angle ; polymer molecular weight ; affine deformation model ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Transient elongational flow, created by forcing a polymer solution across a narrow contraction, is characterized by a high strain rate of limited duration. Due to an inherent short residence time, this type of flow generally is considered as being less efficient in extending isolated flexible molecular coils than “stagnation” point elongational flow. Rheo-optical measurements revealed, nevertheless, a readily detectable birefringence zone above a critical strain rate in the immediate orifice entrance. Birefringence was studied for dilute PS solutions (100-400 ppm) in decalin as a function of fluid strain rate (\documentclass{article}\pagestyle{empty}\begin{document}$\dot \varepsilon $\end{document} = 1000-38,000 s-1) and polymer molecular weight (M = 1.93-10.2·106). Transient elongational flow is complicated by the presence of local orientation distribution along the different streamlines. To account for this effect, a numerical technique has been devised to compute local birefringence (Δn) from experimental retardation (δ). Results show a uniform birefringence distribution across the capillary entrance and a steep decrease with the axial distance. Molecular extension ratio calculated with the Kuhn-Grün theory suggests that polymers may uncoil up to one third of the chain contour length at the approach of capillary entrance. Although extension ratio determined at the inlet could be fitted with an affine deformation model, notable departure from this simple representation is observed when molecular strain is calculated along the streamline. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1483-1500, 1998
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    Suppression of CO2-plasticization by semiinterpenetrating polymer network formation (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1547-1556 
    Details
    ISSN: 0887-6266
    Keywords: gas permeation ; plasticization ; semiinterpenetrating polymer network ; polyimide ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: CO2-induced plasticization may significantly spoil the membrane performance in high-pressure CO2/CH4 separations. The polymer matrix swells upon sorption of CO2, which accelerates the permeation of CH4. The polymer membrane looses its selectivity. To make membranes attractive for, for example, natural gas upgrading, plasticization should be minimized. In this article we study a polymer membrane stabilization by a semiinterpenetrating polymer network (s-ipn) formation. For this purpose, the polyimide Matrimid 5218 is blended with the oligomer Thermid FA-700 and subsequently heat treated at 265°C. Homogeneous films are prepared with different Matrimid/Thermid ratios and different curing times. The stability of the modified membrane is tested with permeation experiments with pure CO2 as well as CO2/CH4 gas mixtures. The original membrane shows a minimum in its permeability vs. pressure curves, but the modified membranes do not indicating suppressed plasticization. Membrane performances for CO2/CH4 gas mixtures showed that the plasticizing effect indeed accelerates the permeation of methane. The modified membrane clearly shows suppression of the undesired methane acceleration. It was also found that just blending Matrimid and Thermid was not sufficient to suppress plasticization. The subsequent heat treatment that results in the s-ipn was necessary to obtain a stabilized permeability. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1547-1556, 1998
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    Infrared characterization of poly(vinyl cinnamate) and its blends with poly(4-vinyl phenol) before and after UV exposure (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1579-1590 
    Details
    ISSN: 0887-6266
    Keywords: infrared spectroscopy ; polymer blends ; poly(vinyl cinnamate) ; UV curing ; hydrogen bonds ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The results of an infrared spectroscopic characterization of poly(vinyl cinnamate) (PVCIN) and its blends with poly(4-vinyl phenol) (PVPh) are reported before and after photo-crosslinking the PVCIN by exposure to UV radiation. The purpose of this article is to demonstrate methodology, and it is shown that quantitative analysis of the fraction of unsaturated (—C=C—) double bonds, “free” (non-hydrogen bonded) and hydrogen bonded unsaturated (—CO—C=C—) and saturated (—CO—C—C—) acetoxy carbonyl groups is feasible in these blends as a function of UV exposure time. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1579-1590, 1998
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    Clustering of water molecules during adsorption of water in wood (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 665-671 
    Details
    ISSN: 0887-6266
    Keywords: clustering ; water ; wood ; adsorption ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Clustering behavior of water molecules during adsorption of water in wood was studied using the Zimm-Lundberg theory. The average cluster size of water molecules was determined with the help of wood adsorption isotherms at five temperatures. The effects of both relative humidity and temperature on average cluster size were studied. Average cluster size progressively increased with an increase in humidity. At humidities corresponding to fiber saturation, larger clusters were formed. Cluster size increased sharply with an increase in temperature at humidities close to saturation. Formation of large clusters at high temperature and humidities close to saturation is attributed to increased fraction of weakly bonded water and capillary condensation in such conditions. A description of adsorption of water in wood was provided in terms of average cluster size. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 665-671, 1998
    Additional Material: 5 Ill.
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    Modeling molecular weight distribution of comb-branched graft copolymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 705-714 
    Details
    ISSN: 0887-6266
    Keywords: molecular weight distribution ; comb copolymer ; branching ; grafting ; nonlinear polymerization ; modeling ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Grafting one type polymer onto a different polymer type may yield a comb-branched copolymer. The branching density has a significant effect on its overall molecular weight distribution. A general model is derived to describe the bivariate distribution of molecular weight and branching density for such comb copolymers. The model is applicable for various grafting mechanisms provided the side chains are randomly grafted onto the backbone. The determining parameters are the molecular weight distributions of backbone and side chains, and the branching density. Analytical expressions are obtained for the cases of the side chains having uniform and Schulz-Zimm distributions. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 705-714, 1998
    Additional Material: 3 Ill.
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  • 192
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    Surface characterization of ion-implanted polyethylene (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 715-725 
    Details
    ISSN: 0887-6266
    Keywords: polyethylene ; ion implantation ; surface structure ; wear ; hardness ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polyethylene (PE) film was implanted with 1000-keV Ar+ ions to a fluence of 5 × 1014 ions/cm2 under high vacuum conditions (2.5 × 10-6 torr) and the film surface was investigated by means of microhardness and microwear measurements, and FTIR/ATR, Raman, and XPS techniques. Ion implantation significantly increased the subsurface hardness and also significantly improved the microwear resistance of the polymer. The implanted surface region of the film was found to consist of two distinct layers. One was the outermost carbon layer with a thickness of the order of 10 nm. In this layer, ca. 75% of carbon atoms were combined by graphitic sp2 and diamond-like sp3 bonds, and the remaining 25% had chemical links with oxygen atoms. Spectroscopic data suggested that the sp2-bonded carbons segregated in graphite-like clusters containing imbedded oxygen atoms, interconnected by the sp3-bonded carbons. The other was the subsurface layer resulting from PE oxidation after ion-beam treatment. This layer was characterized by high contents of O—H and C=O groups as well as ester and double bonds. The chemical composition of the layer was uniform and did not vary over the layer thickness of about 1.4 μm. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 715-725, 1998
    Additional Material: 10 Ill.
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  • 193
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    The effect of crosslinking on thermal and mechanical properties of perfluorocyclobutane aromatic ether polymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1383-1392 
    Details
    ISSN: 0887-6266
    Keywords: BPFCB ; PFCB ; crosslinking ; thermal and mechanical properties ; low dielectric constant ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: As the minimum features in semiconductor devices decrease, it is a new trend to incorporate copper and polymers with dielectric constant less than 3.0 to enhance the performance of the devices. Two fluorinated polymers, poly(biphenyl perfluorocyclobutyl ether) (BPFCB) and poly(1,1,1-triphenyl ethane perfluorocyclobutyl ether) (PFCB), are newly developed polymers with dielectric constants below 3.0. These two polymers have a similar backbone structure, but PFCB has the capability of crosslinking. To know the implications of these two polymers in the semiconductor industry, properties that are important for the integral reliability of Integral Circuits (IC), such as thermal and mechanical properties, should be understood. This comparative study shows that the crosslinking in perfluorocyclobutane aromatic ether polymer can reduce vertical thermal expansion and increase glass transition temperature (Tg) while water absorption, crystalline-like phase, and dielectric constant are slightly increased. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1383-1392, 1998
    Additional Material: 8 Ill.
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  • 194
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    Equation of state of poly(dimethylsiloxane) melts (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 841-850 
    Details
    ISSN: 0887-6266
    Keywords: specific volume ; Tait equation ; compressibility ; scaling parameter ; hole theory ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The pressure-volume-temperature (PVT) properties of three commercial samples of poly(dimethylsiloxane) are studied experimentally and theoretically in the temperature range 25-150°C and for pressure to ∼ 3 kbar. The Tait equation is employed to represent the data at elevated pressure. Isothermal compressibilities are computed for the three samples. The melt data are analyzed in terms of the Simha-Somcynsky hole theory, and scaling parameters of pressure, volume, and temperature are obtained. Satisfactory agreement between theory and experiment is found over the entire range of experimental pressures. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 841-850, 1998
    Additional Material: 6 Ill.
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  • 195
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    Dielectric and dynamic mechanical relaxation studies on poly(aryl ether ketone)s (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 851-859 
    Details
    ISSN: 0887-6266
    Keywords: poly(aryl ether ketone)s ; dielectric relaxation spectroscopy ; dynamic mechanical analysis ; α-relaxation ; β-relaxation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relaxation behavior of four amorphous poly(aryl ether ketone)s was investigated using dielectric relaxation spectroscopy and dynamic mechanical analysis. The temperature dependence of the relaxation times of the glass transition process and the cooperative nature of this process were unaffected by changes in polymer structure. The temperature location of the loss peaks for all polymers progressed smoothly between the low frequency of the mechanical measurements and the higher frequencies of the dielectric probe. Differences were observed in mechanical activation energy and dielectric relaxation strength for one polymer which contained a significant concentration of meta linkages, compared with the para-linked polymers, while relaxation broadness was generally greater in the dynamic mechanical mode. Changes in chemical structure had little effect on the shape, intensity, and location of the β-relaxation peak, the main observation being that the Arrhenius activation energy measured by dynamic mechanical analysis was significantly higher than that calculated from the dielectric data. The dielectric β-relaxation was sensitive to absorbed moisture. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 851-859, 1998
    Additional Material: 10 Ill.
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  • 196
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    Temperature dependence of the activation volume in a nonlinear optical polymer: Evidence for chromophore reorientation induced by sub-Tg relaxations (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 901-911 
    Details
    ISSN: 0887-6266
    Keywords: activation volume ; relaxation ; pressure ; polymer ; reorientation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Second harmonic generation (SHG) was used to measure the temperature dependence of the reorientation activation volume of 4-(diethylamino)-4′-nitrotolane (DEANT) in poly(methyl methacrylate) (PMMA). The decay of the SHG signal from films of DEANT/PMMA was recorded at hydrostatic pressures up to 3060 atm and at different temperatures between 25°C below the glass transition temperature to 35°C above it. The activation volume, ΔV*αβ associated with the long range α-type motion of the polymer remained constant at 213 ± 10 Å3 between Tg - 25°C and Tg + 10°C. At higher temperatures, ΔV*αβ decreased linearly with increasing temperature. The activation volume, ΔV*αβ, associated with short range secondary relaxations was constant over the entire temperature range with a value of 77 ± 10 Å3. The data suggest that above Tg chromophore reorientation is coupled to both the long range and local motions of the polymer; whereas, well below Tg chromophore reorientation is closely coupled to the local relaxations of the polymer. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 901-911, 1998
    Additional Material: 8 Ill.
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  • 197
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    Molecular theory of solutions and blends of heteropolymers. I. Thermodynamics of amorphous multicomponent polymer systems (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 937-958 
    Details
    ISSN: 0887-6266
    Keywords: thermodynamics ; heteropolymers ; phase diagram ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: On the basis of a variational principle a quantitative theory is developed enabling a thermodynamic description in terms of mean field approximation of heteropolymer mixtures of macromolecules with an arbitrary distribution for both degree of polymerization and composition. Rather simple general equations are derived to calculate compositions and volume fractions of spatially homogeneous macroscopic phases as well as to find the cloud-point curve, spinodal, and critical points. Potentialities of general theory are illustrated for copolymers synthesized by traditional methods. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 937-958, 1998
    Additional Material: 1 Ill.
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  • 198
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    Measurement of free-volume hole size distribution in Nafion-117 using positron annihilation spectroscopy (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 983-989 
    Details
    ISSN: 0887-6266
    Keywords: positron annihilation ; free-volume ; Nafion ; free-volume size distribution ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We report a new result of free-volume hole size distribution in water and ethanol-swollen Nafion-117 polymer. With the increase in water content, free-volume hole size decreases, but overall the volume fraction increases. The hole size distribution in dry polymer is seen to be distinctly different from hydrated membranes. The narrow and symmetric distribution in hydrated membrane as compared to dry membrane is believed to be a consequence of crosslinking due to cluster formation. In alcohol-swollen membranes, on the other hand, not only are the free-volume size and fraction seen to be higher, the hole size distribution is seen to be broader compared to dry or hydrated membranes, indicating the effect of penetration of alcohol into the hydrophobic backbone region. We have also examined our results vis-a-vis reported gas diffusion studies in Nafion in the framework of existing free-volume model. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 983-989, 1998
    Additional Material: 4 Ill.
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  • 199
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    Effect of sub-Tg relaxations on chromophore reorientation in corona-poled polymers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1013-1024 
    Details
    ISSN: 0887-6266
    Keywords: nonlinear optical polymer ; pressure ; chromophore reorientation ; poly(alkyl methacrylates) ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Activation volumes for chromophore reorientation were measured for a series of guest-host polymeric materials, indicating a significant coupling between chromophore motion and the glassy α and β relaxation dynamics of the polymer host. The specific systems studied were formed by individually dissolving N,N-dimethyl-p-nitroaniline (DpNA), 4-(dimethylamino)-4′-nitrotolane (DMANT), 4-(diethylamino)-4′-nitrotolane (DEANT), and 1-((4-(dimethylamino)phenyl)ethynyl)-4-((4-nitrophenyl)ethynyl)benzene (DMAPEANT) in poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), and poly(isobutyl methacrylate) (PiBMA). In each of these systems, the isothermal, sub-Tg decay of the second-order optical susceptibility χ(2) was monitored as a function of pressure using second harmonic generation. In each system, the observed decay of χ(2) was represented by a stretched exponential equation from which the decay time τ0 and decay distribution width βKWW were determined. For each dopant molecule, the decrease in activation volume with the increasing size of the polymer host's alkyl side group and the pressure dependence of βKWW were indicative of partial coupling between chromophore rotation and the glassy β relaxation dynamics of the polymer host. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1013-1024, 1998
    Additional Material: 10 Ill.
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  • 200
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    Open spaces and molecular motions of polyether-based network polymers probed by positron annihilation (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 1919-1925 
    Details
    ISSN: 0887-6266
    Keywords: positron annihilation ; polymer electrolyte ; network polymer ; poly(glycidyl ether) ; polyether ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The lifetimes of positrons have been measured for network polymers based on polyethers. From the temperature dependence of the lifetime of ortho-positronium (o-Ps), τ3, for the network polymer of poly(ethylene oxide-co-propylene oxide) [P(EO/PO)], an onset temperature for limited local motions of molecules, Tγ, and the glass transition temperature, Tg, were determined to be 57 and 201 K, respectively. For the network polymer of poly[EO-co-2-(2-methoxyethoxy)ethyl glycidyl ether] [P(EO/MEEGE)], Tγ and Tg were determined to be 57 and 185 K, respectively. For both specimens, above 270 K, the observed linear temperature dependence of τ3 was attributed to the thermal expansion of open spaces in a liquid state. In the temperature range between Tγ and 270 K, for the P(EO/MEEGE) network, τ3 was longer and its intensity was smaller than those for the P(EO/PO) network. These results were attributed to the increase in the size of open spaces for the P(EO/MEEGE) network polymer and the blocking of these regions by motions of side chains and chain ends. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1919-1925, 1998
    Additional Material: 5 Ill.
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