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  • 2005-2009
  • 1985-1989  (480)
  • 1965-1969  (1,849)
  • Physics  (2,329)
  • 201
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1505-1511 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Some years ago, Brather proposed a method for calculation of the real and imaginary parts of the complex dielectric permittivity starting from measurements of isothermal polarization current. This method shows some advantages over the Hamon method, which is normally used. Both methods are applied in this work to the β relaxation of poly(butyl methacrylate). It is concluded that, with the usual accuracy of measurement, a combination of the two methods is advisable; Hamon's method is taken to be a first approximation to that of Brather. Results following the two procedures are compared, and their respective advantages and disadvantages are discussed.
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  • 202
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1495-1504 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A linear lattice model without adjustable parameters provides an accurate description of the magnitude and temperature dependence of the thermal conductivity of Kc of polyethylene crystals parallel (∥) and perpendicular (⊥) to the chain direction. The model shows that heat is transported principally by phonons polarized transverse (T) to the chain direction. Phonons polarized longitudinal (L) to the chain direction contribute about 20% to the heat transport along the chain direction, and negligibly to heat transport perpendicular to the chain direction. Thermal resistance is caused by LTT three-phonon umklapp scattering in the parallel direction, and by TTT scattering in the perpendicular direction. The calculated values for large crystals are Kc∥ = 465 W m-1 K-1, Kc∥ = 0.16 W m-1 K-1 at 300 K, in agreement with experimental estimates and implying an anisotropy ratio of Kc∥/Kc⊥ ≈ 3000. The axial thermal conductivity of polyethylene crystals is extremely high and comparable to that of copper. Comparison with experimental data on semicrystalline samples at lower temperature yields a crude value of mean free path for boundary scattering of about 50 nm, agreeing in order of magnitude with the size of crystalline blocks.
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  • 203
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    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1513-1521 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The D-E (electric displacement vs. field) hysteresis curve of a ferroelectric polymer is conventionally measured by the Sawyer-Tower method. The effect of the electrical conductance of the polymer on the measured hysteresis curve is theoretically analyzed and a new method is proposed for elimination of the error arising from the conductance. Examples of original and corrected hysteresis curves of vinylidene fluoride-trifluoroethylene copolymer are presented.
    Additional Material: 9 Ill.
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  • 204
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1523-1532 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Coherent this films of poly[bis(p-toluene sulfonate) diacetylene] were successfully formed by modified Langmuir-Blodgett techniques using two methods: (i) Photopolymerization of the monomer film at the gas/liquid interface and then transfer to a solid substrate, and (ii) transfer of the monomer film to the solid substrate and subsequent photopolymerization on the substrate itself. The films thus obtained were characterized by traditional force-area isotherms while on pure water subphases. Segments were transferred at either 1 or 10 dyn/cm surface pressure, in different stages of photopolymerization, to glass or germanium substrates. The films on the substrate were characterized by the methods of multiple attenuated-internal-reflection infrared spectroscopy, ellipsometry, contact-potential measurement, and laser Raman spectroscopy. Our results show that the films are multimolecular and about 100 Å thick. Of special interest were the observation of significant anisotropy of oriented dipoles and the ability to obtain excellent spectral data for these very thin oriented films. Raman spectroscopic features are similar to those observed for the bulk polymer, even in the low-frequency region. Polarized Raman spectroscopy confirmed the presence of local anisotropy in these films.
    Additional Material: 6 Ill.
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  • 205
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1555-1562 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The wetting characteristics of free-standing polyacetylene films were determined by using a standard series of wetting liquids. As-prepared films of cis-polyacetylene were found to contain a significant polar contribution to the surface free energy, which became nearly entirely dispersive upon thermal isomerization to the trans form. Both isomeric forms are characterized by a critical surface tension of wetting γc ≈ 51 mN/m, which is considerably higher than that normally obtained from organic polymers. These results have been interpreted with respect to surface oxidation and tested by examining an oxidized film.
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  • 206
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1533-1554 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A model incorporating a rough (disordered) crystal growth surface is capable of treating many of the observations and measurements on the crystal growth of short chains of poly(ethylene oxide) from the melt. A simple preliminary treatment if presented which aims primarily to analyze the growth rate data within one growth “branch,” i.e., for a regime in which crystal thickness is approximately constant. Under these conditions the growth rate is approximately linear with crystallization temperature, as expected for rough growth surfaces, but not for smooth (faceted) ones. Simulation results are included which are in agreement with a simple equation and with experiment. The analysis enables the growth rates for different branches to be compared in a systematic way. A very steep decrease in growth rate with increasing crystal thickness is clearly illustrated, together with some influence of molecular weight. The general trend for chain folding can be seen as a consequence of this steep decrease. Parallel work on systems in which crystal thicknesses vary continuously with crystallization temperature led to the realization that “rounding off” will occur at the crystal perimeter and that this will give rise to an entropic barrier for the crystal advance. This argument is presented in the context of extended-chain and once-folded crystallization, from which it is clear that growth rates should be much lower as crystal thicknesses increase, and for folded-chain as compared with extended-chain crystals. Different morphologies are interpreted in terms of changes in surface structure which are probably due to kinetic as well as equilibrium effects.
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  • 207
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1563-1572 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Single crystals of model ethylene copolymers have been grown in dilute solution. The effects of narrow molecular weith distribution (MWD) and a perfectly random distribution of ethyl branches (ca. 17 per 1000 main-chain carbon atoms) on the unit cell of this ethylene copolymer analog were examined. X-ray diffraction on dried powder samples revealed expansions of up to 1.5% in a and 0.5% in b. a increased as a mild function of molecular weight; the dependence of b on MW was not as clearly defined. Electron diffraction studies on isolated suspensiongrown single crystals yielded lattice parameters much more strongly expanded. The large expansion in the basal plane of the unit cell is hypothesized to be accompanied by a fore-shortening of the projected c-axis distance. This is accomplished by and orthorhombic-to-hexagonal polymorphic transformation in which the chains are hypothesized to adopt a disordered helical conformation. The driving force for this transformation is electron irradiation damage of the single-crystal specimens. The rapidity of the transformation is believed to be due to the model polyethylene crystals being in a higher-energy, defect-containing condition prior to irradiation.
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  • 208
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1573-1584 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The optical constants n and k of polyacrylonitrile (PAN) were determined in the infrared region 3100-700 cm-1 by using theoretical calculations and experimental reflectance spectra. Tests of the validity of the results obtained showed excellent agreement between the measured and the predicted k values. One k value was determined experimentally (k = 0.6155 at V = 2285 cm-1) and showed excellent agreement with that calculated theoretically (k = 0.6153). The p-polarized light was found to be more sensitive than the s-polarized light to the absorbance of PAN films at 77° incidence angle. This sensitivity increased rapidly with p-polarized light for film less than 0.5 μm thick. From the optical constants obtained for p-polarized light at 77° angle of incidence, the sensitivity of the infrared reflection-absorbance (IR-RA) measurements to changes in the functional group concentrations in PAN films was determined for film thicknesses in the region 0.01-10.0 μm. The IR-RA measurements of the —C≡N group and the skeletal mode were for a PAN film thickness of about 0.1 μm.
    Additional Material: 10 Ill.
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  • 209
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2273-2293 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: When a notched polymeric material is stressed, the notch opens into a wide crack tip, exposing a region of high stress concentration. The consequences of electron bombardment of the tip of such a stressed material under vacuum are explored here for the first time. Evidence is presented for electron-induced crack growth at stress far below that needed for crack growth due to stress alone. The electron current densities used in these experiments are sufficiently small that thermal heating of the zone near the crack tip is minimal. To provide information on the phenomena involved, we present simultaneous measurements of electron current, gas pressure, and sample load in response to periodic bombardment of the sample. Experiments involving the bombardment of un-notched polymers under stress are also described. Fractography of the unique structures obtained by fracture due to the combination of electron bombardment and stress are presented and interpreted in terms of a crosslinking mechanism.
    Additional Material: 14 Ill.
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  • 210
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2295-2306 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Changes occur in the structure of drawn polyethylene when it is annealed at temperatures close to that of the drawing process. Measurements have been made of the oxygen barrier properties and of the thermal expansion coefficient in the draw direction on samples over a wide draw ratio range both before and after annealing at various temperatures. The results are augmented by density, creep modulus, and shrinkage observations. All samples show a drop in the barrier properties and an increase in the thermal expansion after annealing. However, whereas high-draw-ratio samples show relatively small effects, the changes observed at low draw ratios are very large, with some barrier properties even lower than those of the isotropic feedstock. The effects are larger at the higher annealing temperatures. The diffusion and expansion measurements are greatly influenced by the amorphous regions in the polymer; these results are interpreted as a relaxation of internal stresses giving rise to greater accessibility of the intercrystalline regions. Further experimental work is required to exploit these techniques.
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  • 211
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2319-2338 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of polyurethane block polymers based on hydroxybutyl-terminated polydimethyl-siloxane soft segments of molecular weight 2000 were synthesized. The hard segments consisted of 4,4′-methylenediphenylene diisocyanate (MDI) which was chain extended with either 1,4-butanediol (BD) or N-methyldiethanolamine (MDEA). The MDEA-extended materials were ionized by using 1,3-propane sultone. The weight fraction of hard segments was in the range 0.13-0.39. The morphology and properties of these polyurethane elastomers were studied by a variety of techniques. All of these short-segment block copolymers showed nearly complete phase separation. The zwitterionomer materials exhibited ionic aggregation within the hard domains. Hard-segment crystallinity or ionic aggregation did not affect the morphology. Hard-domain cohesion was found to be a more important factor than hard-domain volume fraction in determining the tensile and viscoelastic properties of these elastomers.
    Additional Material: 13 Ill.
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  • 212
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    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2359-2368 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: This is a continuation of the preceeding paper, Part I, and presents a discussion of the nature of the precursor structure formation process observed in the flow-induced crystallization experiments described in I. A discussion of stress-induced crystallization theory as applied to these experiments is also given and a first-order analysis of crystal nucleation rates is presented. Conclusions regarding the nature of flow-induced crystallization and our current ability to quantitatively model the overall process are also presented.
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  • 213
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2339-2358 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The process of seeded growth of fibrillar polyethylene crystals has been studied in a tubular flow geometry for 0.01-wt % solutions of a high-molecular-weight polyethylene in xylene. The transformation sequence has been followed visually by using polarized-light illumination in conjunction with a video camera. Data are presented to show that transformation is initiated by the formation of a concentrated, unoriented, amorphous precursor fiber within which oriented birefringent crystals subsequently grow in consequence of the stresses transmitted by the flowing solution. Time constants for the precursor formation, birefringence initiation, and completion of birefringence were measured as functions of temperature and flow rate over a range of growth conditions. Wide-angle x-ray diffraction, overall birefringence, and optical hot-stage melting data were also obtained on the grown fibers. The net result of these observations is to conclude that fibrillar crystal growth during flow is always preceded by the formation of a liquidlike phase transformation which produces the concentrated, unoriented precursor. Subsequent orientation is in consequence of stress-induced crystallization with overall fiber orientation showing an increase with solution flow rate at a fixed temperature and a decrease with temperature at a fixed flow rate. At higher temperatures and lower flow rates, birefringence develops in an oscillatory fashion, indicating a remelting process possibly due to slippage of trapped chain entanglements formed by flow. A discussion is given of the implications of these observations for the understanding of flow-induced structure development, phase transformation, and oriented crystallization; this is expanded upon in a companion paper, Part II.
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  • 214
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2377-2385 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A nonlinear regression analysis is presented to estimate the equilibrium modulus of relaxing rubber networks from G'(ω) or G(t) data. Various semiempirical curve-fitting equations are tested with two-function minimization algorithms.
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  • 215
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2387-2393 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Oriented films of an aromatic polyester containing a triad ester mesogenic group and a decamethylene flexible spacer were studied by polarized light microscopy, small-angle light scattering, and polarized infrared spectroscopy to determine the nature of the alignment of the polymer chains, induced by shearing, which is responsible for the banded or striped morphology observed. The stripes are apparently composed of fibrils arranged in a zigzag manner containing polymer chains packed in a highly ordered, parallel alignment at an angle of ±26° to the shearing direction.
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  • 216
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2407-2409 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 217
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2457-2468 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The translational diffusion coefficients are reported for polystyrenes with molecular weights 2000, 4000, and 9000 in cyclohexane at infinite dilution from 283.2 to 348.2 K. The results suggest that the hydrodynamic radii stay constant to within ±3% and that the real chain for molecular weight 9000 at 308.2 K is well represented by a Gaussian or Monte Carlo model involving the idea of statistical steps. Furthermore, the success of Hildebrand's free-volume empiricism has led to a correlation between Dμ0/T and M which represents the observed diffusivities to within ±2%.
    Additional Material: 6 Ill.
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  • 218
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2423-2442 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The relaxation of an entangled polymeric medium in the viscoelastic plateau is investigated theoretically by using the slip-link representation of topological constraints. In addition to the chain retraction process introduced by Daoudi and investigated theoretically by Doi, we show that two processes contribute significantly to the relaxation: The first, “equilibration across slip-links,” is a longitudinal reequilibration between parts of the chain which have been differently extended or compressed, depending on their initial orientation relatively to the strain tensor. The second, “tube relaxation,” is a mean-field representation of the loss of topological constraints on one chain due to the retraction of the others. Closed analytical expressions for the stress accounting for these three processes are derived and compared with previous theories: the relaxation should be much more progressive than previously predicted, and the terminal time for retraction is reduced significantly by tube relaxation.
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  • 219
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2469-2475 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method is proposed for examining differences in the predictive capabilities of three versions of the free-volume theory of polymer - solvent diffusion using only a small amount of diffusivity data. The utility of the method is illustrated using a limited diffusivity data set for the methanol-poly(vinyl acetate) system.
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  • 220
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2477-2482 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Careful examination of x-ray diffraction patterns from melt-crystallized nylon 11 films show significant discrepancies with the proposed α-form structure. These discrepancies do not disappear after the samples have been annealed. The temperature dependence of the d spacings of the two strongest peaks show further evidence that the melt-crystallized and solution-cast films (α form) possess different crystal structures. These results suggest a different crystal structure for the melt-crystallized films; this would help explain the rather low piezoelectric response of these films and also the failure to observe a rapid decrease in polarization at the transition temperature.
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  • 221
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2499-2504 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The spreading kinetics of molten polyethylene was studied on a flat type A glass surface. Empirical equations are known in the literature which fit the experimental data only at short times. We present a relationship between the surface free energy and the shape of the melt drop interpreted by the θ contact angle. Relating the experimental θ values obtained at different times with the surface free energy (F), we obtain curves F,t. Using isothermal data at 150°C, we could fit them with a linear relationship between In (F-F∞)/(F0-F∞) and In t/t0, where o and ∞ are related to initial and equilibrium conditions.
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  • 222
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2579-2597 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Crazes of different types occur in polymeric systems. Long, sparse crazes develop in less oriented molecular systems, while fine, short, dense crazes occur in highly oriented molecular systems. Different crazing mechanisms and different models may have to be studied for a better understanding of these differences. However, in this report, using one model and one theory, an analysis has been made of the differences in the geometry of craze development. By emphasizing the mechanism of molecular orientation, it is found that the basic differences are essentially attributable to the variation of the anisotropy of the material system as a result of large deformation rather than to any fundamental differences in the crazing mechanism.
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  • 223
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2623-2627 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
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  • 224
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2611-2621 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The 13C NMR spectra of aromatic comblike polyesters obtained from 1,2-icosanediol and isomeric phthalic acids are reported and discussed. The analysis shows that the most informative spectral regions are those of the carbonyl and quaternary carbon resonances, whose peak multiplicities have been interpreted in terms of dyad and triad sequences. The results indicate that the extent of structural characterization possible for the polymers examined is dependent on the type of isomerism of the aromatic acid involved.
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  • 225
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2599-2610 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The results of creep and recovery experiments are reported for a sample of ultrahigh-molecular-weight polyethylene at three different temperatures and creep times in the range from 10 s to 1.47 X 106s. In order to approximate constant-true-stress conditions all the experiments were carried out at the same value of applied stress (4 MPa) and the change in strain during creep was never more than about 2%. It was found that within the range of conditions used the creep and recovery data could be described quite well by a one-dimensional constitutive equation consisting of two terms, one a single integral hereditary term and the other a plasticity term. Further, it was shown that to a very good approximation the idea of time-temperature superposition can be applied to the description of the hereditary term Ĵ (σ, T, t). We believe that the results described here provide greater insight into what constitutes “mechanical preconditioning” of semicrystalline polymers and further provide a relatively simple method for describing the uniaxial creep and recovery behavior of such materials.
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  • 226
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2629-2632 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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  • 227
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2633-2634 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 228
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2635-2635 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 229
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2635-2636 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 230
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 89-103 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The cross-stream migration velocity v⊥ is that part of the velocity of a particle which has no component in the direction of the undistrubed flow. In order to obtain v⊥ for bead-spring model macromolecules, it is necessary to compute the trace of the matrix product \documentclass{article}\pagestyle{empty}\begin{document}$ \underline \ell \cdot \underline {{\rm \hat C}} $\end{document}, where \documentclass{article}\pagestyle{empty}\begin{document}$ \underline \ell $\end{document} denotes the migration matrix and \documentclass{article}\pagestyle{empty}\begin{document}$ \underline {{\rm \hat C}} $\end{document} is the modified Kramer's matrix. In this paper this is done via an eigenvalue calculation, where the eigenvalues are estimated by using the Rouse eigenfunctions. The results are then checked against the few known exact results and excellent agreement is found. It turns out that v⊥ depends on the third power of the molecular weight for free-draining polymers. The dependence upon molecular weight becomes weaker with increasing hydrodynamic interaction until, in the nondraining limit, v⊥ ∝ M2.5. A simple yet accurate formula for v⊥ is proposed. In conjunction with the results for D (of Part I), purely rotational flow fields are shown to be characterized by a single parameter, the particle Peclet number Pe. Up to a constant of order one (actually a function of the hydrodynamic interaction parameters h* and h, which can vary only between 0.8 and 2.057), Pe depends only upon D, the mean-square equilibrium extension R02, and q0, the magnitude of the maximum shear rate for the flow.
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  • 231
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 59-71 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Proton spin-spin relaxation times and the Weibull coefficient have been measured as functions of temperature for poly(ethylene terephthalate) (PET) drawn at 50°C in both the amorphous and the semicrystalline (50%) states. Two relaxation times T2a (long) and T2c (short) are observed for all samples. They are ascribed, respectively, to the relaxation of the amorphous and of the crystalline components including highly strained noncrystalline segments. Effects of initial morphology are found for chain mobility in the noncrystalline regions and for the crystal perfection, evaluated from T2a and the Weibull coefficient μc of the T2c-component, respectively. For all draw ratios, T2a for extrudates prepared from the semicrystalline polymer (C-50) is short compared to that for preparations from the amorphous (A-50) polymer. In the A-50 samples, the perfection of stress-induced crystals increase with increasing draw ratio. In the C-50 samples, the crystal orientation increases, whereas the perfection decreases with increasing draw ratio. To improve the crystal perfection, annealing at higher temperature or longer time is required for C-50 as compared with A-50. The value of μc correlates well with the change in crystal perfection during deformation and annealing.
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  • 232
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 105-111 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Isotactic polypropylene of various degrees of crosslinking was prepared using high concentrations of dicumyl peroxide as the crosslinking agent. Free radicals were generated by γ irradiation of crosslinked iso-PP with a dose of 2.4 Mrad. It was found that the rate constant for free-radical decay is independent of crosslinking in the temperature range from -30 to +20°C. The result is discussed from the point of view of degradation processes taking place simultaneously with crosslinking of iso-PP.
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  • 233
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 113-120 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Audio-frequency dielectric relaxation measurements and differential scanning calorimetry studies have been performed on poly(ethylene oxide) (PEO) complexed with calcium and barium thiocyanate. The measurements were performed over the temperature range 5.5-300 K. The relaxation spectrum for the complexed material consists of two peaks. The activation enthalpy for the peak corresponding to the γ relaxation of pure PEO depends upon the size of the dopant cation. The activation enthalpy for the second peak is independent of the nature of the dopant cation and is very similar to that observed for the αc relaxation observed in pure PEO. Furthermore, the room-temperature electrical conductivity of the complexed materials is much smaller than that for pure PEO and hence very much less than for PEO-complexed with alkali-metal salts. However, above Tg the conductivity rises rapidly and is larger for the barium-thiocyanate-complexed PEO than for the calcium-complexed material. Finally, the DSC studies show that one effect of the ions is to shift the glass transition to higher temperatures.
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  • 234
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 121-128 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Single copper fibers embedded in a polypropylene matrix along part of their length will, on application of a tensile load, break in the absence of transcrystallinity adjacent to the fiber, or pull out of the polymer matrix in the presence of a transcrystalline zone. It is shown that the transcrystalline zone allows thinning of the fiber in the matrix up to the point at which compressive forces created by the shrinkage of the polymer around the fiber on cooling are removed and fiber pullout occurs.
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  • 235
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 129-142 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A simple theoretical treatment of microphase separation in block copolymers [S. Krause, Macromolecules, 3, 84 (1970)] has been extended to the case in which individual molecules of the block copolymer may dissolve in one or the other of the microphases. When the free energy driving force for microphase separation is near zero, the minimum free energy state of the system has a relatively high concentration of block copolymer molecules dissolved in one or in both of the microphases, depending partly on the percent composition of the block copolymer. The theoretical predictions are compared with experimental data in the literature.
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  • 236
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 149-157 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The annealing behavior of polytetrafluoroethylene (PTFE) irradiated with 1 × 105 R of γ rays has been studied in terms of the degree of crystallinity and the melting temperature. At short annealing times the crystallinity changes rapidly to a level characteristic of the annealing temperature. It seems that the crystallization arises from transport of chain segments in noncrystalline regions. The increase in crystallinity at long times of annealing is linear in the logarithm of time. This process is mostly due to elimination of voids formed during γ irradiation, but it also involves slight lamellar thickening and crystallization to form extended-chain regions.
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  • 237
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 199-203 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermal behavior of unfractionated poly(2-methoxy)-Cyanurate, PMCBC- film has been reported. The degradation of the polymer involved two steps. The glass transition temperature, Tg, from DSC and DMA studies is ∼ 200°C. TMA study shows that the glass-rubber transition region is in the range of 157 to 199°C. The thermal stability of PMCBC has been found to be superior to commercially available polymers.
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  • 238
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 245-252 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effects of drawing temperature on the physical and mechanical properties of poly(p-phenylene sulfide) have been studied. A melt-quenched film was drawn by solid-state coextrusion both below (75°C) and above (95 and 110°C) the glass transition temperature Tg (85°C) of PPS. The maximum extrusion draw ratio (EDRmax) increased from 3.4 to 5.6 with increasing extrusion temperature Te from 75 to 110°C. It was found that extrusion drawing just above the Tg of PPS (95°C) produced more stress-induced crystals. A high efficiency of draw in the amorphous region was achieved by extrusion at Te-75°C. The tensile modulus at EDRmax decreased from 5.1 to 3.5 GPa with increasing Te from 75 to 110°C. The low efficiency of draw for the samples extruded at 110°C is explained in terms of disentanglement and chain slippage during drawing due to a less effective network.
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  • 239
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Hydrogenation of polybutadienes with from 8 to nearly 100% vinyl content was used to prepare a series of model copolymers of ethylene and butene-1 with uniform microstructures and narrow molecular weight distributions. They range from readily crystallizable to completely amorphous, depending on the frequency of ethyl side branches (2-50 per 100 skeletal carbons). Melting temperature, secondary transition temperature, density, plateau modulus for the melt, and elastic modulus for the solid were obtained as functions of branch content. The effect of crystallinity on the secondary transition and modulus of the solid is discussed.
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  • 240
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 493-507 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the presence of a sodium arylcarboxylate or arylphenoxide, bisphenol-A polycarbonate (PC) undergoes complex chemical modifications at high temperatures. The reaction mechanism is similar to the one previously established for model systems. Initially, the salt reacts with the carbonate groups of the polymer. This lowers the number-average molecular weight and produces ionic chain ends of the phenoxide type. A fast transesterification reaction is then induced by a continuous exchange between the phenoxide and the carbonate groups, affecting the molecular distribution until an equilibrium is attained. In the presence of CO2, the phenoxide-terminated PC undergoes further chemical modifications (formation of phenyl salicylate and phenyl phenoxybenzoate groups) leading to progressive crosslinking of the polymer.
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  • 241
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    Notes: The phase boundaries in the quaternary system consisting of the polymer poly(2,6-dimethyl-1,4-phenyleneoxide) (PPOPPO is a registered trademark of the General Electric Company.), the solvent trichloroethylene (TCE), and the nonsolvents 1-octanol (OcOH) and methanol (MeOH) are determined. The kinetics of crystallization are investigated by pulse-induced critical scattering. The formation and properties of PPO membranes are discussed in relation to the phase separation phenomena.
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  • 242
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1957-1965 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A realistic rotational isomeric state model has been used to estimate the relative probabilities of the formation of various types of short branches in ethylene-vinyl acetate copolymers that are rich in ethylene. Butyl is predicted to be the most common short branch in all of the copolymers examined, although it is less common in the copolymers than in low-density polyethylene. The major factor responsible for the suppression of the R04 backbiting intrachain radical transfer is the increased preference for trans states at the mainchain bonds flanking the attachment site for an isolated acetoxy side chain.
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  • 243
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1967-1974 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Polystyrene (PS) and poly(2,6-dimethylphenylene oxide) (PPO) are miscible over the complete composition range. The addition of 30-40% PPO to PS changes the mechanical behavior of the material from brittle to tough and ductile. The x-ray scattering curves from unoriented and oriented samples of PS and of PPO are compared with those from a 50/50 blend. The introduction of PPO into PS disrupts microsegregation of phenyl groups into stacks which are a feature of the pure polymer and which may be responsible for formation of sharp shear bands and brittle behavior of PS. The local structure of the blend is significantly different from both PS and PPO.
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  • 244
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2021-2030 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A conformational analysis of isolated chains of polymethylacetylene (PMA), polypentylacetylene (PPA), and poly(t-butylacetylene) (PTA) was carried out taking into account interactions between nonbonded atoms and torsional potentials. It was found that the trans configuration of all three polymers is more stable than the cis configuration, the difference in potential energy between the trans and the cis isomers however being very small for PTA, leading to the possibility of observing a trans→ cis isomerization in some solvents. The calculations show that the substituted polyacetylenes are not found in a planar conformation, the larger deviations from planarity being found with the bulkier substituents: PTA 〉 PPA 〉 PMA. A correlation could be established between the UV absorption limit of the samples and the minimum torsional angle of the potential-energy functions. This relation predicts that the absorption limit is shifted to long wavelengths on increasing the planarity of the molecule. Moreover, UV spectra could be calculated from the potential-energy functions, and it is shown that the potential-energy functions of other substituted polyacetylenes can be calculated from their experimental UV spectra.
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  • 245
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 751-770 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The presence of organic acid salts in bisphenol-A polycarbonate (PC) completely modifies the crystallization mechanism, the melting behavior, and the morphology of the polymer. Organic salts are not ordinary nucleating agents for PC since they react with the polymer, producing metal phenoxide chain ends. On reaction, abundant instaneous nucleation is induced. The seeds are likely to be polymer crystalline fragments preexisting in the melt. The phenoxide chain ends significantly increase the growth rate of the crystalline phase. Melting points and enthalpies of fusion are unusually high, suggesting a high degree of crystalline perfection. Thick multilamellar crystals, which are likely to contain chains in extended configuration, are observed by electron microscopy. No trace of spherulitic morphology is found. The chemical instability of PC containing ionic chain ends is also shown to seriously affect the crystallization rate, the maximum degree of crystallinity, and the melting point.
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  • 246
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 771-786 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An energy analysis based on molecular field theory and Monte Carlo simulation is carried out for the crystal structure of the low-temperature phase of polytetrafluoroethylene (PTFE). PTFE molecules in right-handed and left-handed 13/6 helical conformation are assumed to be packed in a hexagonal array, with each molecule having 13 possible orientations around the chain axis. Interactions between nearest-neighbor chains are calculated from van der Waals interactions between nonbonded C-C, C-F, and F-F atom pairs. First, an approximate molecular field calculation is made of the critical fluctuation of the chain orientation at the order-disorder transition point. This suggests that the low-temperature phase has two chain stems in the unit cell. The Monte Carlo calculation, similar to that used for spin systems, is then applied to the equilibrium packing mode in the low-temperature phase. A crystal structure containing two chain stems in the unit cell is again obtained. A large amount of disorder in the chain orientation is indicated and is believed to be essential in the PTFE crystal.
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  • 247
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 825-829 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 248
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1139-1144 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: pH titration curves for the neutralization of an alternating co-polymer of maleic acid and n-butylvinylether (MAnBVE) with tetrabutylammoniumhydroxide (TBAOH) are reported, and compared to the case of neutralization with NaOH or tetraethylammoniumhydroxide (TEAOH). With TBA+ counterions the compact form of the polymer is stabilized, remaining the preferred form up to higher net charge densities. This tendency is enhanced at higher temperature. Free energy changes of the conformational transition are higher for TBA+ than for TEA+ or Na+ as counterions.
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  • 249
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1127-1137 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The total end-point dose (i.e., the electron irradiation dose necessary for complete destruction of the crystal lattice) was measured at 120 kV and room temperature for poly(ethylene oxide), polyethylene, isotactic polystyrene (i-PS), poly(p-xylylene), ramie and bacterial cellulose, and lobster chitin. On the basis of the results obtained, the possibility of lattice imaging of polymer crystals is discussed. As reported in an earlier preliminary paper, 1.1- and 0.55-nm lattice fringes were resolved in i-PS single crystals by using a conventional transmission electron microscope equipped with a device for low-dose imaging. In this paper, the detailed procedure for lattice imaging of i-PS crystals is described and various features of the lattice images are discussed.
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  • 250
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1117-1126 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The temperature ΘA2 at which the second virial coefficient A2 is zero for ring polystyrenes is 28.5°C in cyclohexane, independent of molecular weight in the range 2 × 104 to 4.5 × 105. This cannot be explained solely by the Candau-Rempp-Benoit theory, which takes into account the effect of segment density on ΘA2 The radius of gyration of a ring is found to be approximately one-half that of a linear polymer with the same molecular weight. The intrinsic viscosities [η] and intrinsic translational friction coefficients [f] of ring polystyrenes with molecular weights ranging from 7 × 103 to 4.5 × 105 have been measured in cyclohexane at 34.5°C (Θ, the Flory theta temperature for linear polystyrenes) and in toluene (a good solvent). The results are compared with those for linear polystyrene. It is found that the Mark-Houwink exponent is less than one-half in cyclohexane at Θ. In toluene it is 0.67 compared to 0.73 for linear polystyrene. The hydrodynamic measurements suggest that large rings are less expanded than the linear polymers with the same molecular weight, contrary to many predictions.
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  • 251
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1145-1164 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of up to 7.82 mol % ionic groups on the stress relaxation and dynamic mechanical (torsion pendulum) properties of poly(styrene-co-sodium styrene-p-carboxylate) was studied. The results obtained were compared with those reported elsewhere for polymers containing the same ionic groups at a different position on the polystyrene backbone (styrene-sodium methacrylate copolymers) and with polymers containing different ionic groups at the same position (styrene-sodium styrene-p-sulfonate copolymers). The results of these comparisons showed that positioning of ionic groups affects the size of ionic aggregates formed, while their type dictates the strength of the forces within the aggegrates.
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  • 252
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1165-1176 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A reliable semiempirical method for predicting glass transition tempertures of linear polymers, random copolymers, and selected crosslinked networks from knowledge of only their chemical structure is presented. For cases in which new moieties not in the database are encountered, a scaling technique of similar moiety contributions has proven successful. The basic database was composed of 178 linear homopolymers ranging from aliphatic to aromatic heterocyclic polymers and 12 random copolymers. The crosslinked networks investigated in this study involved only diacetylene end-group reactions.
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  • 253
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1369-1391 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The experimental measurements necessary to characterize the crystallization kinetics of a semicrystalline polymer are established by adopting a model for the crystallization of the polymer and specifying the range in which thermodynamic variables and other field interactions with the polymer will be varied during processes of interest. The theory for a model of instantaneous heterogeneous nucleation followed by spherulitic growth is developed. To the extent to which this model accurately describes the crystallization, determination of the spherulitic growth rate and nucleation density as a function of temperature then characterizes the temperature-dependent crystallization kinetics of a polymer. These have been measured for poly(butene-1), and, with the adoption of a cooling of the polymer at a constant rate as a processing model, a useful description of the melt crystallization kinetics of poly(butene-1) is given. Literature data for the crystallization rates of linear polyethylene and isotactic polypropylene, poly(butene-1), and polystyrene and compared.
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  • 254
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1477-1484 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The initial slopes and intercepts of Zimm plots of scattering experiments yield the centroidal radius of gyration of the scattering particle. In many cases, it is not possible to measure at sufficiently low angle to obtain accurate initial slopes and intercepts. Errors for missing data can be corrected by using calculated scattering functions as models. Such corrections are given here for polydisperse Gaussian coils.
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  • 255
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1691-1702 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The application of the chemiluminescence technique to the study of polymer oxidative stability is discussed. For the initial stages of oxidation a sigmoidal change in the chemiluminescence intensity with time is justified when the experiment is performed isothermally at high oxygen pressure, whereas at low oxygen pressure and constant heating rate an exponential increase in the chemiluminescence intensity is expected. For advanced stages of oxidation depending on the ratio between the initial and equilibrium levels of hydroperoxides, the intensity of emitted light may either grow or decay until the equilibrium concentration of hydroperoxides is established. Two major parameters of an autocatalytic oxidation (induction time and oxidation rate) can be obtained by carrying out the experiment in an oxygen atmosphere at constant temperature. Alternatively, the extent of oxidation in a certain temperature region can be evaluated when a constant-heating-rate experiment is conducted under nitrogen.
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  • 256
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1713-1722 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 257
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2410-2410 
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    Keywords: Physics ; Polymer and Materials Science
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  • 258
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2395-2406 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Depolarized small-angle light scattering from spherulites in semicrystalline polymers gives rise to a characteristic cloverleaf pattern. For scattering from a single spherulite, the position of the maximum in scattered intensity is readily related to the spherulite radius. For a distribution of spherulites, the maximum should be related to some characteristic measure of the distribution. It is shown for a wide variety of distributions that this characteristic radius is a ratio of high moments of the size distribution, specifically R* ≈ 〈R7〉/〈R6〉. The shape of the light-scattering profile should in principal be related to the nature of the spherulite distribution. Calculations of scattering profiles from a variety of distributions fail to demonstrate this, owing to the strong dependence of scattering power on spherulite size. Exceptions are noted for the case of certain bimodal distributions.
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  • 259
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2411-2411 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 260
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2413-2422 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Simultaneous Fourier-transform infrared (FTIR) spectroscopic and stress-strain measurements have been used to study the II(α)-I(β) crystal phase transformation in poly(vinylidene fluoride) under tensile stress at variable temperature. From the experimental data it can be derived that in the investigated temperature interval from 348 to 423 K the drawing process is inhomogeneous and occurs via formation of a neck. The II(α)-I(β) phase transformation is restricted to temperatures below 423 K and its onset is generally related to the formation of the neck.
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  • 261
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2443-2456 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Using a special thermal field-flow fractionation apparatus capable of working over a broad temperature range, we have observed that retention in the polystyrene/ethylbenzene system decreases substantially as the cold wall temperature increases from 360 to 424 K. Polymers of four different molecular weights ranging from 20,000 to 160,000 were used to verify this conclusion. Based on our earlier work showing that thermal diffusion parameters could be calculated from retention data, we have used the present measurements along with earlier values to generate a compilation of thermal diffusion data over the temperature range from 270 to 424 K. These results are used to develop empirical expressions for the thermal diffusion factor and the thermal diffusion coefficient for polystyrene in ethylbenzene as a function of temperature and molecular weight. It is shown that these results have potential usefulness both in terms of the new physicochemical data obtained and in terms of the guidelines they provide for choosing experimental conditions for thermal field-flow fractionation experiments.
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  • 262
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2483-2498 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dielectric and viscoelastic relaxation behavior of linear low-density polyethylene has been investigated. All three usual relaxation regions occur; however, the α process is more dominant than in conventional low-density polyethylene made dielectrically active through the introduction of carbonyl groups. The observed behavior is very sensitive to orientation and morphology. There are significant differences between oriented samples (stretching or extrusion) and a single-crystal texture specimen. Effects are caused by dipolar orientation and dipolar immobilization, the relative importance of each effect varying with specimen preparation. Active dipolar groups are not carbonyls, or any common organic species, but appear to be due to chain ends having residual dipoles caused by the catalyst used in synthesis.
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  • 263
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2505-2515 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The diffuse-streak x-ray scattering intensity from poly(vinylidene fluoride) form I, which is caused by kink bands with GTnḠ (n odd) conformation contained in the crystallite, decreases with increasing temperature, while the intensity of the 001 reflection does not change. This is attributed to the disappearance of the kink bands in the crystallite, not to partial melting of crystallites containing kink bands. The disappearance of the kink bands suggests that kink motion takes place in the crystallite. Plots of the intensity of diffuse-streak scattering, estimated from the asymmetric part of the 001 reflection, against 1/T roughly give ΔHv = -4.6 kcal/mol. This suggests that the kink band is energetically more stable than the regular structure of form I.
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  • 264
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2517-2537 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In this investigation on samples of high- and low-density polyethylene and ethylene-vinyl acetate copolymers, crystallinities φW and crystalline densities ρcW were obtained with the aid of wide-angle x-ray scattering (WAXS) methods. From small-angle x-ray scattering (SAXS) the following characteristics were obtained either directly or by combination with the WAXS data: values, or limiting values, of the crystallinity φS; crystal densities ρcS; thicknesses of the diffuse boundary layer; number-average thicknesses of the crystalline and amorphous layers; and both number and weight averages of the long periods. It was shown that a discrepancy between φS and φW cannot be attributed to the occurrence of large amorphous regions outside the regular stacks of lamellae; the data were reconciled by assuming that the WAXS crystallinities pertain to the cores of the crystalline lamellae, whereas part of the diffuse boundary layers is comprised in the values of φS. The ρcW and ρcS data of the nonlinear samples show systematic differences, which were attributed to partial incorporation of side groups in the crystalline regions at a concentration estimated to be of the order of 20-40% of the overall concentration. With increasing side-group concentration, the thickness of the core of the crystalline lamellae was found to approach the average length of the linear chain segments between side groups. On the basis of these observations a scheme for the crystallization of nonlinear polyethylene is proposed according to which a number of side groups is encapsulated by the growing crystal. The data can be explained by assuming that all chains, offered at a crystal face where growth takes place, crystallize directly, irrespective of whether the crystallizing stem carries a side group. Further crystallization would then proceed by chain folding at both ends of the first stem, until a noncrystallizable unit is met. In this scheme, allowance is made for about half the stems in the crystals to be connected by folds; this is required in view of the “overcrowding” effect. Finally, the effect of cooling rate and molecular weight on the thicknesses of the crystalline and amorphous layers is discussed, and differences between the amorphous densities of high-and low-density polyethylene are noted.
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  • 265
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2549-2565 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The structure of nylon 6 fibers is analyzed by x-ray diffraction. Our results suggest that only two forms of nylon 6, α and γ, along with lattice distortion and crystallite size, are sufficient to explain the whole range of crystalline structures observed in nylon 6. The γ phase is the preferred initial form in a number of nylon 6 samples. The lattice distortion of the γ form along the chain axis varies from 0.8 to 2.4%, depending on the processing conditions. Upon annealing nylon 6 fibers, the α form is produced primarily by γ-to-α conversion in high-orientation fibers, while additional α form can also crystallize from the amorphous phase in low-orientation fibers. Finally, we show that α crystallites are favored during conditioning of poorly crystallized fibers in a humid atmosphere, and therefore fibers with α as the major crystalline form are produced upon drawing these conditioned fibers. Fibers drawn without lag time contain primarily the γ phase.
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  • 266
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2539-2548 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A method is presented for obtaining from the zeroth-order peak in small-angle x-ray scattering (SAXS) patterns the weight average of the thickness C of crystalline lamellae in polymers close to the melting point. The method fails if a first-order peak can be discerned to be superimposed on the zeroth-order peak. The method was applied, together with the one described in Part I of this series for obtaining the number average of C, to three polyethylene samples of different side-group content which were heated to temperatures close to the melting point. While heating always causes an increasing number of lamellae to melt, a linear sample also shows pronounced thickening of the remaining lamellae. This effect, however, decreases with increasing side-group content, and is virtually absent in a vinyl acetate copolymer containing 53 side groups per 1000 C atoms. A qualitative explanation for the role of the side groups in limiting the crystal thickening processes is put forward. By comparing results obtained after isothermal annealing and during isothermal crystallization from the melt it is concluded that at temperatures close to the melting point the polymers approach a final state which no longer depends on the thermal history of the sample.
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  • 267
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    Topics: Chemistry and Pharmacology , Physics
    Notes: It is proposed here that readily observable viscous deformation is the common underlying phenomenon which is reflected in several kinds of evidence advanced for the existence of a liquid-liquid transition TLL. These include flow temperature Tf measurements, microscope hotstage coalescence, and differential scanning calorimetry (DSC) measurements. A DSC peak observed at Tg in high-molecular-weight bulk-polymerized poly(methyl methacrylate) is discussed in terms of the presence of conformations of low entropy.
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  • 268
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    Topics: Chemistry and Pharmacology , Physics
    Notes: The volatile-component evaporation mechanism proposed by Chen et al. to explain molecular-weight-dependent endothermic peaks found at temperatures above Tg in anionically prepared polystyrenes (PSs) on first heating in open DSC pans is inconsistent with several bodies of literature data which were overlooked, including similar data with closed DSC pans. Moreover, this mechanism appears deficient in explaining details of the dependence of the endothermic peak temperature on M̄n both below and above the entanglement molecular weight Mc, with a sharp increase in slope at Mc. The original fusion-flow mechanism of Stadnicki et al. is compatible with all other known literature data including results on thermal PS and PMMA fractions. Hot-stage microscope examination of powdered anionic PSs supports the Stadnicki mechanism from M̄n = 1900 to at least M̄n = 350,000. Addition of small amounts (ca. 1 wt %) of benzene or ethylbenzene to PS results in open-pan DSC traces without endothermic peaks but with an endothermic slope change indicating gradual loss of diluent at decreasing rate as the temperature is increased from below Tg up through the TLL region.
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  • 269
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 179-189 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In fibrils composed of highly extended chains, a characteristic clustering of defects into laminae perpendicular to the chain axes is often found. One model suggested to explain this morphology assumes that initially the defects are randomly distributed but that under heat treatment the system undergoes a spinodal phase separation in which the defects cluster to form the laminar structure. Here we report results obtained from numerical simulations which support this picture. We then explore the more general question of the response of such a nonequilibrium system to small imposed patterns. We examine under what conditions the patterns are amplified or attenuated.
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  • 270
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 159-177 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Modern theories of the dynamics of concentrated polymeric liquids have not yet accounted for the effects of polydispersity to a sufficient extent. In order to approach quantitatively the problem of polydispersity, a model is proposed here which is based on the concept that the “tube” of constraints around a chain enlarges as the relaxation proceeds. Predictions of linear viscoelasticity obtained with this model compare favorably with experimental results on homopolymeric blends reported in the literature. However, the theory is limited to the case of very long chains and it embodies an arbitrary, if plausible, closure assumption in the self-consistency scheme. Thus, quantitative agreement remains incomplete.
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  • 271
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 191-197 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Solutions of polystyrene of molecular weight 4.5 × 106 and 8.4 × 106 in mixed solvents of carbon tetrachloride/methanol were filtered through track-etched mica membranes at low membrane velocities. The unperturbed hydrodynamic radius of the polymer was always larger than the pore radius. The reflection coefficient σ, defined as the fraction of polymer held back by the membrane, was determined from material balances as a function of solvent flow rate per pore q, volume percent CCl4 of the solvent, and polymer concentration C0. In the dilute region (C0 〈 C*) σ was found to depend primarily on q and was essentially independent of chain size (or solvent goodness), molecular weight, and pore radius. In the semidilute region (C0 〉 C*) σ decreased significantly as C0 was increased.
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  • 272
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 227-229 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 273
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 205-226 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new technique of decoration of the fold surface of polymer crystals is described. It is similar in methodology to gold decoration, but makes use of vapors of crystallizable polymers, principally polyethylene, as decorating material. Upon condensation and crystallization, the highly anisometric decorating molecules become oriented parallel to the fold direction. They build up small crystalline lamellae which, seen edge-on, appear as elongated rods and can be easily observed by conventional transmission electron microscopy. This decoration technique reveals the sectorization of polymer single crystals grown from solution. It can be used to determine the local fold orientation (with a resolution of ca. 10 nm) of polymers crystallized under a wide range of conditions, including crystallization from the bulk. The technique reveals that under all crystallization conditions so far investigated the outermost part of the polymer fold surface is relatively ordered, and the folds and/or loops are, as a rule, oriented nearly parallel to the macroscopic growth front.
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  • 274
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 231-239 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 5 Ill.
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  • 275
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 521-535 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The copolymer system HBA (4-hydroxybenzoic acid) and HNA (2,6-hydroxyhaphthoic acid) has been studied mainly by means of differential scanning calorimetry. Heat capacities for the two homopolymers and three copolymers are reported from 175 to 650 K. The heat capacities are additive with composition. The whole copolymer system represents an example of a mesophase intermediate between the liquid-crystalline and the condis-crystalline state with a small amount of crystallinity. The disordering transitions (520-620 K) have a eutecticlike phase diagram. The transitions to the isotropic states occur above the decomposition temperatures (600-700 K). The glass transitions (377-434 K) show normal changes in heat capacity (31-34 J/K mol), but are broadened to as much as 200 K.
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  • 276
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 537-555 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Fourier-transform infrared spectroscopy was used to study the hydrogen bond-breaking process in nylon 66 and two model compounds. The resulting enthalpy and entropy values indicated that while there is no interaction between adjacent amide groups in the polymer chain, there is, nevertheless, a substantial cooperative effect in the transverse hydrogen bond direction. We have also established that any analysis of hydrogen bond breaking in semicrystalline polymers (i.e., nylon 66) below the melting point should include a crystallinity correction factor. Extrapolation of our data above the melting point of nylon 66 yielded a 26% retention of hydrogen bonding.
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  • 277
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 557-563 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The rotational mobility of nitroxide radicals in polypropylene samples with draw ratios varying from 1 to 18 has been studied between 30 and 110°C by the ESR technique. The drop in the rotational frequency with increasing orientation correlates very well with the behavior of various other measures of molecular mobility such as organic vapor sorption, proton spin-spin relaxation times from NMR, and dynamic mechanical loss factor. This implies that each of these parameters is a good indicator of the amount of free volume in the amorphous regions. Annealing at high temperature relaxes the amorphous chain segments, thereby increasing the spin-probe rotational frequency in the drawn samples to values even higher than that in the quenched isotropic material.
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  • 278
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 565-574 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Mesomorphic copolymers were synthesized by incorporating varying ratios of azelaic acid and (+)-3-methyl adipic acid into copolyesters based upon 4,4′-dihydroxybiphenyl. Introduction of the phenylene (+)-3-methyl adipate unit broadens the temperature range of the nematic phase of the azelate homopolymer and, at the same time, produces a chiral nematic (cholesteric) mesophase which exhibits various iridescent colors. Circular dichroism measurements were used to determine the pitch of the cholesteric liquid crystals. The pitch decreased gradually with increasing temperature, and the inverse pitch increased in direct proportion to the molar content of the units containing (+)-3-methyl adipate. The twisted cholesteric structure could be conserved by quenching to produce films with various colors at room temperature. Annealing these films at a temperature immediately below that of the crystal-mesophase transition improved the regularity of the cholesteric structure.
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  • 279
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 601-606 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 7 Ill.
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  • 280
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 575-589 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Concentrated polystyrene solutions were investigated on the inception and cessation of simple shear flow by means of the technique of two-color flow birefringence. Both monodisperse solutions of various molecular weights and bimodal mixtures were studied. The molecular weight affected both the amount of overshoot in the birefringence and the response time on the inception of shear flow. Large overshoots in birefringence, up to 250%, and undershoot in the orientation angle were observed. The shear stress and the first normal stress difference were calculated by using the stress-optical rule. The amount of strain at the peaks in the stress growth curves are presented along with the steady-state viscosity and primary normal stress coefficient. The experimental results are compared qualitatively with theoretical predictions of various molecular models.
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  • 281
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 591-599 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Depolarization of fluorescence resulting from the transport of electronic excitations in chromophore-containing polymers is investigated as a technique for detecting deviations from ideal-chain statistics. An approximate expression for the fluorescence anisotropy that depends only on the pair correlation function of chromophore labels is presented. This approximation is shown to be accurate for particular cases of long-range correlations, short-range correlations, and no correlations among chromophore positions. The formalism allows fluorescence depolarization experiments to be used as a probe of macromolecular pair correlation functions.
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  • 282
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 609-614 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Raman-active modes have been detected in amorphous poly(vinyl acetate) in the frequency region 20-160 cm-1. The low-frequency spectrum appears as a broad band for all three molecular weights examined. Spectra were recorded at two temperatures, 293 and 77 K, and found to show similar characteristics at both temperatures. The presence in solid amorphous polymers of broad structureless bands in general and their significance are discussed.
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  • 283
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 615-621 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A relation is proposed which gives the error in determination of molecular weights of polymer samples using the extrapolation of the Mark-Houwink-Sakurada equation into the low-molecular-weight region. The error is directly related to the exponent α of the Mark-Houwink-Sakurada equation and the relation is the same for a number of polymer + solvent systems.
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  • 284
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1085-1085 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 285
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1085-1085 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 286
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1086-1086 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
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  • 287
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    Notes: A method is described for performing simultaneous measurements of small-angle x-ray scattering and differential scanning calorimetry. The experiment is made possible through a combination of the high flux afforded by the storage ring at the Stanford Synchrotron Radiation Laboratory, a linear position-sensitive detector with rapid response time, and a differential scanning calorimeter developed for optical microscopy. The feasibility of the technique is illustrated by examining the melting and crystallization of a polyethylene specimen. This example demonstrates the power of the technique and the accuracy and reliability of the scattering and thermal data.
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  • 288
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1099-1108 
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    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Tetrafluoroethene (TFE)-chlorotrifluoroethene (CTFE) and TFE-bromotrifluoroethene (BTFE) copolymers have been synthesized by solution copolymerization over the entire range of comonomer composition. Crystallinity data are reported and first- and second-order transitions have been investigated by DSC. Glass transition temperatures of TFE-CTFE copolymers vary in a nonlinear fashion in the range defined by the homopolymers conforming best to the Johnston equation; the behavior in the TFE-BTFE system is more linear. Whereas TFE-BTFE copolymers show a steep decrease of melting temperature at higher BTFE content, due to the amorphous character of the polymers, more regular behavior was found for TFE-CTFE copolymers. Enthalpies of fusion are also reported. The results are discussed in relation to copolymer composition and structure and are compared with data on tetrafluoroethene-hexafluoropropene (FEP) fluorocarbon resins.
    Additional Material: 9 Ill.
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  • 289
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1247-1254 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Absorption measurements at millimeter-wave frequencies (50-151 GHz) are reported for dried and hydrated polyamide-6. The measurements were extended over the temperature range from liquid helium to room temperature using the oversized-cavity technique. For dried polyamide-6 (water content ≤ 0.5% w/w), a nearly linear increase with frequency and an exponential increase with temperature of the absorption coefficient is found between 50 and 300 K. This frequency and temperature dependence is described by relaxation processes in asymmetric double-well potentials. The observed relaxation times are on a picosecond time scale, thus suggesting an assignment to the NH…OC hydrogen bonds and the adjacent peptide unit (O=C—N—H). Hydration results in an increase of the absorption over the whole temperature and frequency range. This is attributed to the fact that the water of hydration is adsorbed in the neighborhood of the hydrogen bonds and changes their dynamical properties. This interpretation is supported by IR-spectroscopic measurements of the shift of amide I and amide II after hydration.
    Additional Material: 6 Ill.
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  • 290
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1263-1265 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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  • 291
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1267-1269 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 292
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1271-1274 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 9 Ill.
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  • 293
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1297-1307 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dielectric results at frequencies between 6 × 10-4 and 105 Hz are given for the β relaxation region of poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA), poly(butyl methacrylate) (PBMA), and poly(isobutyl methacrylate) (PisoBMA). Apparent activation energies and relaxation strengths are calculated, as well as the relaxation time distribution and the form factor of the Fuoss-Kirkwood equation. It is found that in PMMA, PEMA, and PBMA, the activation energy of the β relaxation is the same, the maxima occurring at the same frequency for the same temperatures, in accordance with the dynamic mechanical results of Heijboer, the dielectric results of Mikhailov, and at variance with data of Tetsutani et al. It is also found that the form factor follows the same temperature dependence. Data on the β relaxation of poly(hydroxyethyl methacrylate) (PHEMA), not previously reported, are also presented, and the displacement toward high temperatures of the β relaxation of PisoBMA and PHEMA is justified.
    Additional Material: 13 Ill.
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  • 294
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1275-1295 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Rheological and rheo-optical studies are reported for isotropic solutions of the mesogenic rodlike polymer poly(1,4-phenylene-2,6-benzobisthiazole) (PBT). Several PBT samples were used with average contour lengths from 95 to 135 nm. Concentrations were varied over a range just below the concentration Cc for the formation of an ordered (nematic) state. The predictions of a single-integral constitutive equation of the BKZ type utilizing experimental estimates of the distribution of discrete relaxation times is compared with experimental data on the steady-state viscosity ηκ, the recoverable compliance function Rκ, and the steady-state flow birefringence as functions of the shear rate κ, with satisfactory results. The relaxation of the shear stress and the flow birefringence on cessation of steady-state flow at shear rate κ are also compared with the single-integral constitutive equation, and it is found that in the nonlinear response range the data can be superposed over a wide range in κ. The overall behavior is qualitatively similar to that for flexible chains, which can also be fitted by the single-integral constitutive equations over similar ranges of η0R0κ, with η0 and R0 the limiting values of ηk and Rκ for small κ. Of course, the dependence of η0 and R0 on concentration and molecular weight differs markedly for rodlike and flexible-chain polymers.
    Additional Material: 11 Ill.
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  • 295
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1309-1324 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been made of various approaches to the problem of evaluating the permeability of a binary composite polymeric material on the basis of certain fundamental theoretical assumptions. In particular, it is assumed that the component phases form well-defined microscopic domains and do not interact with each other or with the penetrant. The main characteristics and relative merits of these treatments are considered in detail, and it is shown that considerable information can be obtained about the range of validity and physical significance of certain well-known formulas, which were previously applied in a largely empirical way. These results indicate specific fields of application (which include filled or semicrystalline polymers, foams, block and graft copolymers, and nonhomogeneous polymer blends) for each of the formulas in question and lead to a deeper understanding of the relation between permeability or analogous properties (such as thermal or electrical conductivity, electrical permittivity, elastic modulus, etc.) and the structural characteristics of composite polymeric (and other) materials.
    Additional Material: 4 Ill.
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  • 296
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1353-1367 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Brown has shown that low-angle electron diffraction (LAED) may be used to determine fibril diameters D and spacings D0 of crazes in thin polymer films. He found, however, that the D and D0 determined for air crazes in polystyrene (PS) thin films were larger by about a factor of 3 than those in PS bulk crazes determined by using small-angle x-ray scattering (SAXS). We have repeated Brown's LAED experiments and find that the discrepancy may be caused by an aging effect. Our fresh crazes have D and D0 values from LAED that are comparable to those of bulk PS crazes determined by SAXS. As the craze ages, however, fibrils retract and coalesce in wide regions of the craze, leading eventually to an observable “skin.” Aged crazes thus have much larger D and D0 values than do fresh crazes. The large molecular mobility of the PS molecules in the fibrils necessary for this aging to occur at room temperature has important implications for fibril failure.
    Additional Material: 11 Ill.
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  • 297
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1325-1351 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Three EPDM network families with various degrees of chemical crosslinking and slightly crystalline below about 350 K have been characterized by thermoviscoelastic and equilibrium swelling measurements. Between 300 and 450 K the thermoviscoelasticity of these elastomers, whether cured or not, is complex. Important differences from previous results on noncrystalline EPDM networks are their dependence on waiting time and temperature history below 350 K, and an equilibrium modulus for the uncured elastomers. These effects increase with rising ethylene content of the EPDM and are related to the crystallinity in the networks. A previously proposed modified time-temperature (t-T) superposition scheme is also applicable to these data, and the resulting frequency shift functions aT are of the usual WLF type. The vertical shift functions for the relaxational components bT are different from those for the equilibrium moduli. Experimental data demonstrate that the absolute values of the relaxational components, i.e., G″ (ω) and H(τ), are not changed by small variations in crystallinity. In addition, larger variations in crystallinity do not affect their frequency dependence, only their absolute values. On the contrary, the equilibrium modulus, and therefore all characteristics containing this as a component, is extremely sensitive to small variations in crystallinity, and hence in temperature. The linear viscoelastic characteristics of these slightly crystalline networks and their deviations from thermoviscoelastically simple behavior are discussed as functions of the ethylene content, temperature, and degree of crosslinking of the elastomer. The data provide evidence for three contributing factors, namely chemical crosslinks, crystallinity, and a more disordered type of crystallinity termed microparacrystallinity.
    Additional Material: 17 Ill.
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  • 298
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1585-1595 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Completely crystalline samples of oligoethylene glycol di-n-alkyl ethers, H(CH2)nO-(CH2CH2O)m(CH2)nH, where m is 9 or 15 and n is in the range 12-18, were orientated in capillaries by slow crystallization in a temperature gradient. X-ray scattering from the long spacings of the oriented samples, rotated continuously through 360°, was concentrated on the equator of a Debye-Scherrer photograph and many orders of reflection could be seen (e.g., up to order 30). The intensities of these reflections were analyzed by use of a model electron density distribution through the layer structure. Thus it was shown that the central oxyethylene block, in helical conformation, is oriented normal to the layer end plane, while the end alkyl bolcks, in planar zigzag conformation, are tilted relative to the layer end plane at an angle in the range 70°-64°.
    Additional Material: 9 Ill.
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  • 299
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1597-1609 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two crystal modifications have been found for poly(3,3-bisethoxymethyl oxetane) [poly- (BEMO)] by wide-angle x-ray powder diffraction and differential scanning calorimetry, while only one modification has been found for poly(3,3-bisazidomethyl oxetane) [poly(BAMO)]. Melting temperatures for the two polymers were nearly the same, varying from about 70 to about 90°C depending on the thermal treatment; higher crystallization temperatures resulted in higher melting temperatures. The equilibrium melting temperature T*m was found to be 125 and 128°C for poly(BEMO) and poly(BAMO), respectively, by using the Hoffman-Weeks extrapolation procedure. Measurement of the melting-point depression of Poly(BEMO) and poly(BAMO) in dibutyl phthalate yielded enthalpy of fusion values of 2.25 and 12.8 kcal/mol, respectively. The percent crystallinity for poly(BEMO) and poly(BAMO), respectively, was calculated to be 55-60 and 13-30% based on DSC and x-ray analysis.
    Additional Material: 9 Ill.
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  • 300
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    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 1629-1636 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Microstructural Composites of polyacetylene/polybutadiene blends were prepared by polymerizing polyacetylene in a matrix of polybutadiene. The polyacetylene in the blends can be doped with iodine to produce electrically conducting composites. Thus a new material is formed which retains many of the electrical properties of doped polyacetylene but whose mechanical properties are different from those of either polyacetylene or polybutadiene.
    Additional Material: 8 Ill.
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