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  • Electronic Resource  (3,180)
  • 1980-1984  (2,597)
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  • Electronic Resource  (3,180)
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  • 101
    Electronic Resource
    Electronic Resource
    Heat transfer in injection molding of crystallizable polymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 692-697 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A model is proposed for the treatment of heat transfer with crystallization during plastics processing in general, and injection molding in particular. The model incorporates experimentally determined crystallization kinetics parameters. It permits the calculation of the distribution of both temperature and crystallinity in the molding. Theoretical predictions are in good agreement with experimental measurements in both injection molding and a prototype apparatus.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240911
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  • 102
    Electronic Resource
    Electronic Resource
    Foreword (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 723-723 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241002
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  • 103
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241001
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  • 104
    Electronic Resource
    Electronic Resource
    Microstructural aspects of failure in semicrystalline polymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 770-785 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Microstructural features of semicrystalline polymers are reviewed, as are the roles of chain properties and thermal history in their development. Experimental results relating failure properties to microstructural detail are described. General models to explain inter- and intra-spherulitic failure behavior are proposed. Important are (a) the role of spherulite size in boundary incompatibility, (b) competition between spherulite boundary cracking and intraspherulitic yielding, (c) competition between localized (interspherulitic) fracture and dispersed (intraspherulitic) fracture.
    Additional Material: 26 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241007
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  • 105
    Electronic Resource
    Electronic Resource
    Craze failure by midrib creep (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 809-813 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It has been known for some time that crazes thicken during growth mainly by drawing in fresh material from the craze-bulk interface, keeping the average craze fibril draw ratio approximately constant. Since Creep effects contribute only negligibly to craze growth rates these effects have generally been considered unimportant regarding craze breakdown. However, it is also known that the first stage of fracture is failure of the craze midrib, which is a highly drawn, very thin region down the middle of a craze. Because of the very low thickness of the midrib it has little influence on craze behavior, and information on midrib behavior is difficult to obtain. It is the purpose of this paper to attempt to rationalize what information is available.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241010
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  • 106
    Electronic Resource
    Electronic Resource
    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241101
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  • 107
    Electronic Resource
    Electronic Resource
    High strain-rate shear deformation of a polyurethane elastomer subjected to impact loading (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 851-861 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Experimental techniques have been developed to produce and measure large amplitude one dimensional compression and shear waves in a polyurethane elastomer (Solithane 113). Experimental measurements consisted of time-resolved compression and shear amplitude measurements at different distances from the impact surface. The data were analyzed to provide compression and shear wave velocities, and the corresponding stress-stain curves on the microsecond time scale. The ability to measure directly the high stain rate shear response is a new development and has provided interesting results. The shear modulus varies between 3 and 9 kbar for compressive stresses ranging between 2 and 14 kbar. In contrast, shear modulus values inferred from quasi-static measurements of bulk and Young's modulus under static high pressure are negligible. These comparisons suggest a high rate dependence of shear modulus in the glassy state. The shear strain curves suggest an elastic-plastic response with yield strengths ranging from 0.12 kbar to 0.25 kbar with increasing compression for the compressive stress range investigated. Results of compression experiments are also presented.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241104
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  • 108
    Electronic Resource
    Electronic Resource
    Impact modification of poly(vinyl chloride) with chlorinated polyethylene I. Blend morphology (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 869-876 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The solid state morphology of chlorinated polyethylene (CPE)-modified poly(vinyl chloride) (PVC) and the relationship of blend structure to impact strength and mode of fracture have been investigated. Selective staining of the CPE phase showed that the morphology of the two phase system changes with increasing CPE content from a dispersion of discrete CPE particles to a network structure enveloping the primary PVC particles. The network formation coincides with a transition from brittle to ductile impact fracture. When the blend was mixed for too long a time or above the fusion temperature of the primary PVC particles, the CPE network was destroyed. The resulting indistinct domain structure is associated with a reduction in the impact properties.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241106
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  • 109
    Electronic Resource
    Electronic Resource
    Thermodynamic behavior of solid polymers in uniaxial deformation (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 908-914 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The heat and work of uniaxial deformation were measured for two commercial polyurethane elastomers and a low density polyethylene using a new deformation calorimeter. Internal energy changes in the materials resulting from deformation were calculated from the difference between the heat and work according to the first law of thermodynamics. The elastomers were found to exhibit complete reversibility for small and large strain deformation cycles as determined from the absence of a permanent internal energy change, even though one of these undergoes strain-induced crystallization and melting. The low density polyethylene behaves irreversibly even at small strains, and will store 30 percent of the deformation work as internal energy during drawing at room temperature.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241110
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  • 110
    Electronic Resource
    Electronic Resource
    Deformation behavior of plasticized poly(vinyl chloride) membranes with barium content (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 936-940 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Barium complexes were embedded in plasticized poly(vinyl chloride) (PVC) membranes. Effects of these metallic complexes were followed as a function temperature and strain rate. It was found that both the elastic modulus and yield stress decrease with barium content. This behavior is attributed to a lack of uniform structure and the existence of irregularities and voids in the bulk membranes. Another factor which may reduce the tensile strength is te internal and interfacial residual stresses developed at the metal-matrix interface. These internal stresses and the structural nonuniformity influence the electrical conduction mechanism and performance of the PVC matrix ion-selective electrodes during aging. Also, it was observed that the yield stress of these membranes has a strain rate and temperature dependence.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241114
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  • 111
    Electronic Resource
    Electronic Resource
    Orientation in amorphous polymers I. Preparation and testing of oriented samples (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 956-964 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Orientation effects in amorphous polystyrene are studied using a uniaxial stretching experiment. The rheological properties of the polymer are determined from an analysis of creep data obtained from the tensile apparatus, and oriented polymer samples are prepared at different extension ratios and rates of stretching. From birefringence and tensile strength measurements on oriented samples of polystyrene, it is shown that the tensile strength is not a unique function of the birefringence. It is proposed that the tensile strength may depend not only on the average orientation, as reflected by the birefringence, but on which portion of the relaxation spectrum is preferentially oriented.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241204
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  • 112
    Electronic Resource
    Electronic Resource
    Thermal conductivity and thermal expansion behavior of glass fiber-reinforced rigid polyurethane foam (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 943-949 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The thermal conductivities and the thermal expansion curves of glass fiber-reinforced rigid polyurethane foams with various fiber lengths, various fiber volume fractions and various matrix densities were determined experimentally. Additionally the thermal expansion coefficients of these materials at room temperature were examined in terms of the interaction between fiber and matrix. The thermal expansion properties were analyzed successfully with the analogous treatment which is applied to the mechanical tensile behavior.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241202
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  • 113
    Electronic Resource
    Electronic Resource
    Stress relaxation of glass-fiber-reinforced rigid polyurethane foam (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1000-1005 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Flexural stress relaxations were measured for rigid polyurethane foams (PUF) and glass-fiber-reinforced rigid polyurethane foams (FRU). The results were successfully analyzed in terms of the five element Maxwell model: (1) Samples reinforced with longer fibers exhibit reduced stress relaxation and reduced temperature dependency of stress relaxation; (2) The increased expansion ratio reduces the flexural modulus of both reinforced and non-reinforced materials, but the stress relaxation tends to increase greatly at the higher temperature for PUF, while not so greatly for FRU; (3) The temperature dependency of E1 decreases as longer fibers are used to reinforce the polyurethane. The dependency is minimal for the polyurethane reinforced with continuous fibers, where the reinforcing effect is maximal; and (4) The activation energy calculated from τ2 according to the Arrhenius plot is smaller for the longer fiber reinforced polyurethane foams.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241209
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  • 114
    Electronic Resource
    Electronic Resource
    Mechano-chemical degradation and stabilization of polymersBased on an invited lecture to the IUPAC Conference, Amherst, Massachusetts July 1982 (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1007-1020 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: When polymers are subjected to sheer, macroalkyl radicals are formed which lead to accelerated oxidation. This may occur in the polymer melt during processing or under conditions of mechanical fatigue at lower temperatures (e.g., in cross-linked rubbers). Under these conditions, chain-breaking electron acceptor (CB-A) antioxidants are found to be relatively more effective than under conditions of thermal oxidation and the evidence suggests that the reduced and oxidized couples of some antioxidants, for example, phenol/phenoxyl or hydroxylamine/nitroxyl, can deactivate radicals catalytically.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241302
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  • 115
    Electronic Resource
    Electronic Resource
    Surface-modified kevlar fiber-reinforced ionomer: Dynamic mechanical properties and their interpretation (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1047-1050 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A quasi-three-dimensional model was applied to the composite of ionomer and isotropically oriented discontinuous poly(p-phenylene terephthalamide) (PPTA) fibers having the surface modified by carboxymethyl groups in order to predict the Young's modulus from the properties of the constituent materials over a wide temperature range. The model in which the modified PPTA fibers are dispersed in ionomer matrix in a three-dimensional network is composed of series and parallel models. A good agreement between calculated and experimental values was eventually obtained. For comparision, the complex modulus of the composite was also evaluated by application of the Halpin-Tsai equation modified by Nielsen. The calculated values agreed with the observed values below 240 K, whereas the calculated values above 260 K were significantly lower than the observed moduli.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241309
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  • 116
    Electronic Resource
    Electronic Resource
    Kinetic analysis of the data on the effect of humidity on the stability of poly(butylene terephthalate) (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1043-1046 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of temperature and humidity on polymer aging is well recognized. Gardner and Martin and Kelleher, et al., have collected extensive data on the effect of temperature and humidity during the course of aging of poly(butylene terephthalate) (PBT). They proposed an empirical equation to predict the half-life of aging. In the present work the data of Gardner and Martin have been reanalyzed to evolve an empirical equation which is applicable to the entire range of changes during aging.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241308
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  • 117
    Electronic Resource
    Electronic Resource
    Thermal stability of polyethylene terephthalate (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1056-1063 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics of thermal and thermal-oxidative degradation of polyethylene terephthalate (PET) have been investigated as a function of melt temperature, melt residence time, melt environment, and drying environment. Rates of thermal and thermal-oxidative degradation were measured in terms of: weight loss of volatile degradation products, decreasing inherent viscosity, and increasing carboxyl end group concentration. Thermal-oxidative degradation was also investigated by Differential Scanning Calorimetry. Calorimetric results show that thermal-oxidative degradation of PET is an exothermic reaction, with an apparent activation energy of 117 kJ/mol. Melt temperature, melt residence time, melt environment, and drying environment have all been found to affect the degradation of PET. Analysis of inherent-viscosity kinetic data has been carried out, utilizing existing theories based on a random chain scission mechanism. Activation energies of 117 and 159 kJ/mol have been calculated for air-dried and vacuum dried samples respectively.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241311
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  • 118
    Electronic Resource
    Electronic Resource
    New model of physical aging effects in enthalpy recovery (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1104-1110 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new model of enthalpy recovery is presented which is based on a microscopic-relaxation theory. The microscopic basis and manner of construction of the enthalpy-recovery model are discussed in detail. The qualitative features of the model are illustrated using numerical simulations. In particular, the way in which the effects of physical aging are produced is discussed. The qualitative features observed in differential-scanning-calorimetry experiments are reproduced, and a program of extensive simulations is proposed and outlined. The present microscopically based model is also used to suggest interpretations and possible modifications of currently used phenomenological enthalpy recovery models.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241405
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  • 119
    Electronic Resource
    Electronic Resource
    Characterization of polymer conformation and morphology through small-angle neutron scattering - A literature review (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1-21 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Small-angle neutron scattering, SANS, stands forth as one of the most important of the new tools for evaluating polymer chain conformation and morphology. This paper reviews the SANS literature through 1982, with a few early 1983 references added. The theory of SANS is outlined and compared to light scattering. SANS values of polymer molecular weights and radii of gyration obtained in the bulk state were found to be in agreement with values obtained from dilute solutions by light scattering. In each case, deuterated fractions of polymer were inserted into the hydrogeneous matrix, or vice versa, to provide contrast. Several new research areas are then discussed, including unidirectional stretching of elastomers, stress-relaxation, polymer-polymer miscibility, crystallization from the melt compared with crystallization from dilute solutions, nonclassical aggregation during bulk polymerization of thermoset systems, morphology of polymer blends, block copolymers and ionomers, the core-shell structure of latexes and polymer blocks, and grafts as surfactants in emulsions and latexes. Much new and sometimes unexpected information is being provided by the SANS research now in progress.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240102
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  • 120
    Electronic Resource
    Electronic Resource
    The effect of pressure and temperature on time-dependent changes in graphite/epoxy composites below the glass transition (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 57-66 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Effects of pressure and temperature on time-dependent changes in physical/mechanical properties of graphite/epoxy composites were investigated. Samples were cut from the eight-ply-thick laminates of commercially used composites, post-cured, and then quenched to environments of various temperature and pressure. Time-dependent changes in their properties were analyzed by thermal and thermomechanical (dynamic mechanical) measurements. An increase in the glass-transition temperature was found to occur as a function of time. The rate of this process was enhanced by an increase in temperature and/or a decrease in pressure. An explanation was offered in terms of types and mechanisms of molecular events that occur in the glassy state. Time dependent decrease in free volume (and enthalpy) takes place but is not the sole mechanism responsible for the observed increase in Tg. After a certain period of time (which depends on T and P of the environment), additional crosslinking appears to take place.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240107
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  • 121
    Electronic Resource
    Electronic Resource
    Recent advances in the theory of polymeric alloys (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 70-78 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The theory of multicomponent polymeric systems, termed “polymeric alloys”, composed of block copolymers, homopolymers and solvents is discussed. We first review the microscopic interfacial properties of polymeric mixtures, highlighting the interfacial activity of block copolymers as emulsifying agents in incompatible homopolymer blends. We then turn to some interesting features of the phase diagrams, such as homopolymer-induced mesophase formation and the existence of eutectic points, similar to those for metallurgical alloys. Finally, we address problems in polymer dynamics and present some recent new theoretical results based on the tube model.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240203
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  • 122
    Electronic Resource
    Electronic Resource
    Gas chromatographic determination of the interaction parameter of poly(ethylene oxide)/poly(methyl methacrylate) blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 287-290 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Inverse gas chromatography (IGC) has been used to investigate thermodynamic miscibility of a molten poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA) blend. Toluene, benzene, and chloroform have been employed as probes in pure and mixed stationary phases of these polymers. Experimental measurements have been taken over a narrow range of temperatures because of the high PMMA glass transition temperature as well as the degradation of the PEO. The interaction parameter χ23 determined at 150°C is slightly negative and dependent on the interacting probe, as has been also noted in previous chromatographic studies on polymer-polymer miscibility. The last section is devoted to a model calculation, using Flory's equation of state theory. Different χ23-concentration curves have been simulated, with the interaction energy parameter X23 as an adjustable parameter.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240410
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  • 123
    Electronic Resource
    Electronic Resource
    A quantitative description for the optical properties of crystalline polymers applied to polyethylene (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 328-344 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A quantitative model which described the microscopic and macroscopic refractive index properties of uniaxially oriented crystalline polymers has been extended in relation to molecular bond polarizabilities in this work. Application of this extended modeling methodology in analyzing measured refractive index data for a series of unoriented and oriented samples of linear polyethylene provided Δco = 0.0585 and Δao = 0.194 as the most probable crystalline and noncrystalline intrinsic birefringences for samples exhibiting spherulitic morphology. With these intrinsic birefringences, noncrystalline orientation functions were determined from the optical measurements coupled to the model and the results compared to values obtained from infrared measurements. This comparison of noncrystalline orientation functions, as well as from low density polyethylene reported by other investigators, provided experimental justification for our modeling methodology to examine the possibility of changing intrinsic birefringences for polyethylene as a function of orientation and morphology. The results of this examination demonstrated that values for Δco = 0.0585 and Δao = 0.12 should be used for both low and high density polyethylene samples oriented above the spherulitic to fibrillar transition region.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240507
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    “Living” anionic polymerizations in a continuous stirred-tank reactor under sustained feed oscillations (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 391-397 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: “Living” anionic polymerizations carried out in a continuous stirred-tank reactor (CSTR) and operated under forced-feed oscillations are theoretically studied to investigate the effects on time average values of average chain lengths, polydispersity, and reagent conversions. The instantaneous mean residence time is maintained constant. The period of the oscillations is varied between 60 and 0.05 mean residence times, and various amplitudes are considered. Some advantages are observed with the periodic forcing as compared to the steady operation; polymers with average polydispersities above 10 may be produced at low frequencies, with polydispersities below the steady-state value of 2 at intermediate frequencies, and with polydispersities of 2 but with increased monomer conversion at fast cycling.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240602
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  • 125
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    Effects of surface treatment on the mechanical properties of carbon fibers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 455-459 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Surface of the carbon fibers developed from PAN (polyacrylonitrile) has been modified using such methods as air oxidation, nitric acid treatment, and anodic (electrolytic) oxidation. By choosing optimum treatment parameters, the tensile strength of such fibers has been found to increase by about 60 percent over that of the untreated value. A quantitative estimation of the surface groups formed during the treatment shows an increase in number with severity of the treatment. Further, removal of these functional groups from the fiber surface during degassing at 1000°C also influences the mechanical properties of the carbon fibers considerably. Results have been discussed in detail.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240702
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  • 126
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    A note on the numerical treatment of the thermally developing flow in screw extruders (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 482-487 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper proposes a new solution for the problem of thermally developing flow in a single-screw extruder with power law fluids. It is shown that a transformation to a Lagrangean frame enables one to extend the solution to extrusion situations where appreciable “pressure back flow” exists. The utility of the model is demonstrated using a polystyrene melt as a model fluid.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240706
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  • 127
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    Durability and failure analyses of a silane treated α-Al2O3/polyethylene joint in wet environment (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 493-500 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The durability of the joints, consisting of α-Al2O3 primed with γ-aminopropyl triethoxysilane (γ-APS) and polyethylene (PE), in wet environment is investigated as a function of the γ-APS thickness, dehydration of γ-APS prior to joint formation and redrying the joint after a certain exposure. The joint strength measured by 180°s peel is found to decrease with exposure time in wet environment more rapidly in water than in 100 percent RH. With exposure time, the debonded area increases from the edges toward the central area of the joint. Relatively thin γ-APS treatments on α-Al2O3 appear to provide a more durable joint than thicker γ-APS treatments resulting in an optimal thickness in the range of 0.3 ∼ 1 percent γ-APS concentration level. Dehydration of γ-APS leads to more durable joints with an optimal condition found between 1 ∼ 2 days of dehydration at 100°C in vacuum. Regardless of the γ-APS thickness and dehydration history, the failure in the de-bonded area seems to occur by the hydrolysis of γ-APS near the α-Al2O3 side and by the deformation of polyethylene (cohesive failure) in the peeled area, as characterized by SEM and ESCA. The debonded area in the dried joint recovers little strength, but in the central bonded areas, the strength is mostly recovered, characterized by cohesive failure of polyethylene. Diffusion of water in γ-APS near the α-Al2O3 side rather than the PE side can explain at least qualitatively most of the observed trends. The effects of γ-APS thickness and dehydration on the durability in wet environments are compared with those on adhesion promotion in dry environments as well as on their respective failure mode.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240708
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    Thermally stimulated creep of polyethylene, polypropylene, copolymers, and blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 127-134 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The technique of Thermo Stimulated Creep (TSC) has been applied to the study of anelastic properties of polyethylene, polypropylene, their copolymers and blends. In the temperature range -200 to 100°C, complex TSC peaks were observed in all samples, namely around 0°C, about the same temperature as for the homopolypolymer polypropylene. By applying “fractional stresses”, with a convenient choice or the loading program, these peaks have been experimentally resolved. Two components can be distinguished: 1. The “low temperature” component is characterized by mechanical retardation times following a compensation law. It has been attributed to microbrownian motions of polypropylene sequences liberated at the glass transition of the “true” amorphous regions. 2. The “high temperature” component which is influenced by thermal treatment has been assigned to microbrownian motions of polypropylene sequences liberated at the glass transition of the “constrained” amorphous regions. In block polymers, an additional TSC peak is observed around -50°C: it has been associated with the glass transition of ethylene-propylene-rubber (EPR) interphase. The coupling of this interphase with polyethylene and polypropylene phases is insured by diffusion of some ethylene and propylene sequences in-EPR. At about -140°C, a TSC peak associated with the low temperature component of the glass transition of polyethylene can be distinguished in all the materials studied.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240210
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  • 129
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    Influence of composition, crystallization conditions and melt phase structure on solid morphology, kinetics of crystallization and thermal behavior of binary polymer/polymer blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 563-586 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Results of an investigation on the morphology, the crystallization and the thermal behavior of several binary crystallizable blends are reported. The composition, molecular mass and crystallization conditions strongly influence the crystallization and the thermal behavior as well as the overall morphology of crystallizable binary blends. Quantities such as nucleation density (N), radial growth rate (G) of spherulites, overall rate of crystallization (K), and equilibrium melting temperature (Tm) are strongly dependent upon composition, crystallization conditions, and molecular mass of components. The type of dependence is to be related to the physical state of the melt, which, at the crystallization temperature, is in equilibrium with or coexists with the developing solid phase. In the ease of compatible blends such as poly(ethylene oxide)/poly(methyl methacrylate) the depression observed for G and Tm is mainly to be attributed to the diluent effect of the non-crystallizable component. For such a blend it is found that, after crystallization, the non-crystallizable component is trapped in intralamellar regions increasing the distance between adjacent lamellae. Depression of G, in the case of incompatible blends such as isotactic polypropylene/rubbers is mainly accounted for by rejection and deformation of rubber drops. The coexistence during crystallization of different processes such as molecular fractionation and segregation, preferential inclusion or dissolution of molecules with lower molecular mass and/or high degree of steric disorder of the crystallizable component in the phase rich in non-crystallizable component and vice versa may explain some minima observed in the plots of Tm′ and Tm, vs. composition in the case of blends semicompatible in the melt. It was found that the addition of a second non-crystallizable component causes drastic variations on some morphological and structural quantities of the semicrystalline matrix (isotactic polypropylene or nylon 6) such as the shape, dimensions, and regularity of spherulites and interspherulite boundary regions and lamella and interlamella thickness. In some cases the formation of new boundary lines connecting occluded particles are also observed. Such phenomena may have great importance on crack propagation and on impact behavior as well as on the tensile mechanical properties of binary blends characterized by a semicrystalline polymer component with a relatively high Tg and a rubber-like component with a lower Tg.
    Additional Material: 42 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240809
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    Poly(butyleneterephthalate)-poly(ethylene-co-vinylacetate) polymer blends. Part II (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 618-621 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The more distinctive morphological features which appear in the micrographs of fracture surfaces of polymer blends of poly(butyleneterephthalate)(PBTP) with poly(ethylene-covinylacetate) (EVA), obtained by polymerizing in different conditions dimethylterephthalate (DMT) and 1,4-butanediol (4G) in the presence of EVA (with 4 percent w/w of vinylacetate, VA,), are shown and discussed. The micrograph investigation clearly points out that the adhesion between EVA particles and PBTP matrix increases with the extent of reaction between PBTP and EVA and, for the same time of reaction, by changing from an anchor to a paddle agitator. The mean diameter of the particles is also affected by time of reaction and by the geometry of the agitator, decreasing when the adhesion increases.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240815
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    On the scale-up of plasticating extruder screws (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 626-632 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In the most commonly used scale-up method of plasticating extruder screws, the screw channel depth is increased by the square root of the diameter ratio while the screw RPM is decreased by the square root of the diameter ratio such that the output rate increases proportionally to the square of the diameter ratio. This scale-up method, largely based on the pumping function of the screw, often leads to a higher melt temperature, a higher screw horsepower consumption per unit output rate and an inferior melt quality from the larger diameter screw. Analysis of the common scale-up method reveals that, although the shear rate in the melt is kept constant, the average residence time and the peripheral screw speed are increased for the larger diameter screw. Our recent study on the melting mechanism also reveals that the melting capacity increases less than the pumping capacity. A detailed examination of the common scale-up method in this paper shows that the pumping capacity and the solid conveying capacity increase more than necessary while the melting capacity increases insufficiently.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240904
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  • 132
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    Roll fusing of toner particles on rough papers in the xerographic process (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 662-672 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper deals with squashing of toner particles in a variety of paper topographies in the roll fusing of toner images in xerographic machines. The model developed can be used for predicting the mean spreading ratio of toner particles related to fix level with given rheological properties and fusing temperature and pressure.The deformation of toner particles is solved with respect to the asperity pressure encountered in the contact between the roll and the paper surfaces. Various contact situations are considered, among them: toners on smooth papers, on tops of paper asperities, and at valleys of a paper surface. In addition to rheological properties and fusing conditions, toner spreadings also depend on toner size, paper roughness, and the rubber modulus of the fuser roll.Based on an integration algorithm, statistical averages of toner spreadings can be computed in terms of distribution functions of toner and paper asperity height. Comparisons of theoretical predictions with measurements show good agreement over a broad range of data.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240908
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  • 133
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    The flow of thermoplastic melts: Experimental and predicted (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 501-510 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The flow of polypropylene, nylon 6,6, and 33-percent glass-fiber-filled nylon 6,6 into a tensile bar mold was investigated. Pressures needed to fill the cavity and runner system were measured as a function of fill time and melt temperature. The experimental results were compared to pressures predicted using the Moldflow flow-analysis programs. Correlation between experimental and predicted pressures was good provided that accurate input data to the computer programs were used. The choice of runner diameter in the approximation of the irregular shaped runner of this tensile bar mold was found to be important, since the runner length was approximately 40 percent of the total flow length. Material properties of particular importance were thermal conductivity, viscosity, and no-flow temperature (the temperature at which the resin will no longer flow). Viscosity/shear rate/temperature data are needed for the computer programs and two methods of obtaining the data were examined: an Instron capillary rheometer and a capillary nozzle on an injection-molding machine. Good agreement between the two methods was found for polypropylene over a shear rate range of 100 to 10,000 s-1. Only the injection-molding capillary nozzle could be used for the nylon- and glass-filled nylon due to the thermal degradation that occurred in the Instron rheometer.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240709
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  • 134
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    Inter- and intrachain elastic interactions in polymers and polymer blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 520-524 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The damped Debye lattice or damped torsional oscillator model for viscoelastic relaxation in the primary transition region takes into account elastic interchain interactions as well as the more usually invoked intrachain interactions. To test the importance of these interchain interactions, we have applied this model to compatible blends formed from atactic polystyrene (PS) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO). Qualitative predictions of the variation of stress relaxation behavior of the blends as a function of PPO concentration have been made. Also, predictions concerning properties of these blends upon dilution suggest very distinctive behaviors. We have measured stress relaxation master curves in the primary transition region of PS-PPO blends of various concentrations and have found that the predicted behavior is indeed observed. Furthermore, the unusual effects of dilution on the properties of these blends have been observed with dioctyl phthalate used as diluent. These results show that inter- as well as the more familiar intramolecular elastic interactions are important factors in determining viscoelastic behavior of bulk polymers in this transition region.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240803
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    Polypropylene based polymer blends: Fields of application and new trends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 544-554 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The new industrial strategy in the polymer field requires the transformation of plastic “commodities” into “specialties”. From this point of view, polypropylene (PP) plays an important role both for its intrinsic properties such as high melting temperature, low density, high chemical inertness and for its capability to be produced with different morphological and molecular structures, to be modified with the addition of other polymers or mineral fillers and to be grafted with functional groups. The present range of special and reinforced polypropylene grades includes: elastomer-modified PP, elastomer-modified filled PP, glass fiber-reinforced PP, filled PP, esthetic filled PP, flame-retardant PP, and thermoplastic elastomers. New trends for significantly improving this family of polymers involve impact resistance, processability, durability, dimensional stability, elasticity, and surface properties. A positive answer to this complex emerging demand will put, as indicated, in this work, “special and reinforced polypropylene grades” in a position to successfully compete with technopolymers in some important, rapidly growing application sectors.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240807
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  • 136
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    A rheo-optical study on the reformation of structure in racemic poly(γ-benzyl glutamate) liquid crystals (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 355-360 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Transmitted light intensities were measured by means of the polarized light technique for the nematic liquid crystal phase of racemic poly(γ-benzyl glutamate) (PBG) in m-cresol at 25°C after cessation of steady flow at shear rates ranging from 0.2 to 110 s-1. Weight-average molecular weights of PBG used were 1.5, 2.1, and 2.6 × 105, while the concentrations varied between 20, 30, and 40 wt percent. Transmitted light intensities with crossed and parallel polarizers, Ix and I|, show wavy changes with time after cessation of steady flow, indicating the retardation decreases with time. An attempt was made to explain experimental results on the basis of a simple model, in which not only relaxation of molecular orientation but also effects of the wall and disclination were taken into account.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240510
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    Small angle scattering from ampholytic styrene ionomersSome of these results were presented at the American Physical Society March Meeting, Dallas, 1982, and at the IUPAC Macro 82 Meeting, Amherst, July, 1982. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 385-390 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Small angle neutron scattering experiments were made on an ionomer synthesized from perdeuterostyrene and an ion pair comonomer. A Debye plot based on data from the sample with lower ion concentration gave a correlation length of 5.3A. Clustering is not significant in this sample. With a higher concentration of ionic groups a peak in the scattering curve is interpreted as due to clusters about 20A in diameter. These studies along with X-ray scattering and electron microscopy also indicate the presence of larger ion rich domains.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240514
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    Flow analysis of rubber transfer molding (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 403-414 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An experimental study has been carried out on rubber I transfer molding. It reveals that the filling is frequently limited more by the resistance of flow across the transfer pot than by resistance of flow through the sprue holes into the cavities. A mathematical model has been derived, which predicts semi-quantitatively the molding behavior observed. The mode1 predicts that fill time is proportional to the ratio of compound viscosity divided by molding pressure raised to about the fourth power. For the common cases where most of the fill time is from the resistance to the transverse flow on the top of the sprue plate, the fill time is proportional to about the fifth power of the ratio of transverse distance divided by the charge thickness. Experimental results showed that preheating and mastication of the compound reduced transfer time substantially. The charge pattern did not seem to have a major influence on transfer time.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240604
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  • 139
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    Drying of plastics with time-varying surface concentration: Experiments on slabs and application to equipment analysis (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 460-468 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Drying of hygroscopic plastics in preparation for molding or extrusion is characterized by very low moisture levels in the polymers and by very low humidity in the drying air. In these circumstances, diffusivity is essentially independent of moisture concentration but surface concentration will vary with time in the general case. An exponential surface concentration/time function is derived from fundamentals and applied to the solution of the diffusion equations for slabs and spheres. Under ideal drying conditions, the solutions reduce to the elementary case in which cs = cf for θ 〉 0. For non-ideal drying, the exponential factor b̃ in the surface concentration function appears in the solutions of the diffusion equations. Experiments on slabs were used to verify the analysis since ideal or non-ideal drying conditions could readily be set up with molded slab samples. Experimental drying curves are in agreement with theory. To complete the analysis for engineering applications, equations for counter flow heat transfer in the dryer hopper are derived and combined with the diffusion solutions to generate dryer performance data.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240703
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  • 140
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    Mechanical properties and molecular aggregation of soluble aromatic polyimide (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1021-1025 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Dynamic and static mechanical properties of a soluble aromatic polyimide (PI 2080) were investigated. It, unlike poly(pyromellitimide) (PI), was essentially amorphous in X-ray diffraction and did not exhibit any heterogeneous two-phase structure having ordered phases after annealing at temperatures around its glass transition temperature. The mechanical properties including thermal-distortion temperature and elastic recovery were not much affected by the annealing. The difference in molecular aggregation and mechanical properties between PI 2080 and PI may be due to their different chemical structures. The flexible carbonyl group and the statistical distribution of copolymeric repeating units in the main chain of PI 2080 seem to prevent the formation of molecular order.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241304
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    A Wide-angle X-ray diffraction method of determining chopped fiber orientation in composites with application to extrusion through dies (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1051-1055 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A method of determining fiber orientation in composites using wide-angle X-ray diffraction (WAXS) is described. Oriented crystalline fibers are suspended in an amorphous polymer matrix. The WAXS reflects characteristics of the fiber are used to determine the mean orientation and orientation distribution of the crystallographic axes representing the polymer chain relative to preferred axes located in the test specimen. The chain direction crystallographic axis is taken as representing the fiber axis, and the orientation of this axis to represent the orientation of the fibers. Experimental studies were carried out using Kevlar (poly(p-phenylene terephthalamide)) fibers suspended at a 20 volume percent loading in a polymethyl methacrylate matrix. The Kevlar fibers had Hermans orientation factors of 0.92. Specific attention is given to how through circular dies. We have examined both extrudates and the material frozen-in when the composite in the reservoir and die is cooled to room temperature. Fiber orientation factors, corresponding to Hermans orientation factors, 0.3 to 0.38 were obtained for the extrudates. Orientation factors for fibers within the die is about 0.45. Specially prepared completely oriented samples had orientation factors of 0.93, which closely corresponds to the orientation of the fiber.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241310
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    Molecular dynamics of physical aging in the glassy state (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1071-1078 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: We review first recent results concerning the relation between the relaxation of extensive thermodynamic and of viscoelastic functions. In the underlying theory a central role is assigned to a particular excess-free volume function h. It was originally introduced in a theory of the equilibrium melt. The time dependence of h can then be derived from volume (or enthalpy) recovery data and serves to predict other quantities, such as mean-square density fluctuations and viscoelastic-temperature shift factors during the aging process. Next the physical basis and results of two kinetic theories of volume relaxation are summarized. In both approaches the h-function is employed as an expression of the molecular dynamics in the drive to equilibrium. The first describes a gradual elimination of free-volume gradients through a diffusion process, characterized by a diffusion parameter, varying with the local free volume in accord with a Doolittle relation. The second, a stochastic theory, derives expressions for the matrix of transition rates between different free-volume states, the resulting spectrum of retardation times, and the size distribution of free volume in the relaxing system. Satisfactory agreement between observed and predicted volume recovery of poly(vinyl acetate) ensues. In the limit of an infinitesimal temperature jump, both theories yield a Williams-Watts correlation function as an approximate interpolation expression. The exponent β, however, varies in time with a constant value of approximately 0.60 over a limited time interval.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241402
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  • 143
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    An application of a unified relaxation model to the aging of polystyrene below its glass temperature (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1111-1116 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Torsional creep measurements of physical aging in high-molecular-weight glassy polystyrene are presented. The data are analyzed using a relaxation model which has been successful in quantitatively describing a wide range of relaxation phenomena. The model predicts the time-functional dependences of the creep compliance and, upon physical aging, a possible systematic change of the functional dependence as creep is shifted to longer time scales. These features are established by experimental measurements. Good quantitative fits are found using a restricted application of the model in which all but one of the model parameters are held constant with annealing. Relations of the present study to other polymer relaxation phenomena are discussed.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241406
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  • 144
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    Effects of stress and vapor exposure before and during aging on enthalpy relaxation of poly(vinyl chloride) (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1123-1129 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Enthalpy relaxations in glassy poly(vinyl chloride) following varied pre-aging treatments and under varied aging conditions have been compared through observations of sub-Tg endothermal DSC (differential scanning calorimetry) aging peaks. The extent of enthalpy relaxation for a fixed time and temperature of aging is progressively enhanced by the imposition and release of increasing mechanical stress before aging. The same effect is produced by sorption and desorption of increasing amounts of CO2 or CH3Cl vapor before aging. In contrast, the continued application of mechanical stress, or the presence of vapor, during the aging period suppresses enthalpy relaxation. The extent of suppression increases with increasing vapor pressure and solubility or increasing stress. These effects are interpreted as consequences of an increase in the enthalpy of the polymer under mechanical or sorptive stress and an enthalpy relaxation following the release of this stress. In addition to these effects on the DSC endotherm, a pronounced exotherm between the aging peak and Tg is observed for samples which have undergone shear yielding or orientation either before or during aging. This exotherm may be the result of release of stored strain energy during the DSC scan.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241408
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  • 145
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    Relaxation induced changes in electrical behavior of glassy chalcogenide semiconductors (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1149-1154 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Effects of structural relaxation and the glass-transition process are clearly manifested in the electrical behavior of glassy-chalcogenide films. Analysis of the transport and trapping of photoinjected carriers and of the thermal generation of free carriers in the bulk reveal that in chalcogenides each of these processes is mediated by a specific manifold of localized electronic states residing in the mobility (forbidden) gap. It is demonstrated that in the vicinity of Tg the population of these states varies systematically with the structural state of the glassy film always tending toward a temperature-dependent quasi-equilibrium. The present-observations thus clearly establish the structural origin of key electronic-gap states and simultaneously reveal the mechanism by which relaxation impacts electrical behavior.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241412
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  • 146
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    Spherulite growth in isotactic polypropylene-based blends: Energy and morphological considerations (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1155-1165 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The kinetics of isothermal crystallization of polymer blends in which the matrix is a crystallizable polymer is considered. It is shown that depending on the difference in interfacial energies the inclusions are rejected or engulfed by the growing spherulite. Other factors influencing rejection, engulfing, and/or deformation of dispersed particles of the second polymer are the viscosity of the melt, the spherulite growth rate, and the size of dispersed particles. If the difference in interfacial energies is positive, then rejection or engulfing requires additional work to be done by the crystallization front. This dissipation of energy decreases the spherulite growth rate. It is estimated that the rejection of the second component is the most important phenomenon in the crystallization of blends. The spherulite growth rate of isotactic polypropylene in blends with low-density polyethylene and several elastomers was studied as a function of crystallization temperature and concentration. The comparison of growth rate data with morphological changes occuring during crystallization of blends studied shows very good agreement with the theoretical predictions based on energetics considerations.
    Additional Material: 15 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241502
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  • 147
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    Enhancement of melting through corotating disk processors (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1260-1269 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Melting mechanisms in the corotating disk processor (DISK-PACK) Farrel Company trademark.are presented and discussed. This polymer processor consists of disk elements attached to a shaft with the entire assembly fitted into a housing. All polymer processes are induced by the drag action of the jointly moving disks, compared to only one moving surface characteristic of single screw extruders. Experiments carried out in a 150 and 7-1/2″ diameter corotating disk polymer processors indicate that polymers can be melted by either of two mechanisms: The drag melt removal mechanism and the dissipative mix-melting mechanism. The former mechanism occurs when a molten film is constantly removed from both sides of the solid bed, while the latter takes place throughout a system of molten and solid particulate mixture occupying the space between the disks. A theoretical model is presented for the drag melt removal (DMR) mechanism in such corotating disk polymer processors. The additional capability to induce a dissipative mix-melting (DMM) mechanism can increase the melting rate obtained from conventional mechanism by 300 percent and lower the exit melt temperature substantially. Melting rates over a broad range of conditions are presented for a variety of polymers.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241609
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  • 148
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    Preamble (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1283-1283 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241702
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  • 149
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    The determination of the thermodynamic interaction parameter χ in polymer blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1291-1299 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The miscibility of polymer blends is related to the polymer-polymer interaction parameter χ23, Several methods can be used to evaluate this parameter and five of the most important ones are reviewed: two equilibrium methods (melting-point depression and vapor sorption), a transport method (inverse-phase gas chromatography) and two scattering methods (neutron scattering and small-angle x-ray scattering). Examples are cited where χ23 values for a given blend were determined by several of these methods. This comparison leads to the conclusion that a reasonable agreement is often reached despite conceptual differences between the methods involved.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241705
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  • 150
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    A review of miscibility enhancement via ion-dipole interactionsPresented in part at ACS meeting, St. Louis (April 1984) and reported in macromolecules. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1306-1311 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It is shown that ion-dipole interactions induce considerable miscibility enhancement in blends of styrene ionomers with poly(alkylene oxides). Dynamic mechanical studies, in conjunction with transparency and brittleness of the samples, are used to evaluate miscibility. The effect is clearly thermodynamics in that phase separation can be induced in miscible samples by raising the temperature, with miscibility reestablished ons cooling. The miscibility enhancement in these systems is compared with that resulting from hydrogen bonding. In addition to the styrene/alkylene oxide system, ion-dipole interactions are found to be effective in enhancing the miscibility of many ionic polymer/polar polymer pairs. The ionomers used in this study were styrene lithium methacrylate and ethyl acrylate lithium acrylate copolymers, while polyethers, polysulfides, polyesters, polyimines, and substituted polyethylenses served as polar polymers.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241707
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  • 151
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    Permeability of oxygen and water vapor through polyethylene/polyamide films (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1337-1347 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Oxygen and water vapor permeability studies were carried out on binary polyethylene/polyamide immiscible blends incorporating three polyethylene resins (LDPE, LLDPE, and HDsPE), and three polyamide resins (PA-6, PA-6,6, and modified PA-6,6m). It was found that the incorporation of PA into PE reduces the oxygen permeability while water vapor permeability is increased. In the range of 0 to 30 weight percent of PA, the oxygen permeability of PE was reduced by a factor of 2.8 to 3.6. Maximum water vapor permeabilities increased: for HDPE by a factor of about 2.6 to 3.1 and for LDPE and LLDPE blends by about 1.6.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241711
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  • 152
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    Modification of surface structure and crystallinity in compression-molded poly(phenylene sulfide) (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1383-1389 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The structural modifications and the changes in crystallinity of poly(phenylenesulfide) (PPS) during high-pressure molding and curing have been investigated as a function of pressure and temperature using wide-angle X-ray scattering (WAXS), infrared absorption (IR) and scanning electron microscopy (SEM). It has been found that the crystalline content of the molds varies with applied pressure as Pα where α is 1.5. Major changes in the IR spectra are found in the range of 800 to 600 cm-1 and attributed to structural modifications which have also been noted in the scanning electron micrographs. These various results have been mainly explained on the basis of plastic deformation and flow during the high-pressure molding process.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241803
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    General treatment of polymer crystallization kinetics - Part 1. A new macrokinetic equation and its experimental verification (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1396-1401 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new macrokinetic equation of the autocatalytic type is proposed to describe the polymer crystallization process. The derived equation is compared with the known Avrami equation. It is shown to be consistent with the results of isothermal experiments.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241805
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  • 154
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    Nonlinear viscoelastic response in two dimensions - numerical modeling and experimental verification (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1409-1416 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Recently we developed a nonlinear viscoelastic constitutive model which called the Phases Model (PHM) [10]. The main advantages of the PHM over existing nonlinear viscoelastic models are that it lends itself to simple, straightforward calibration of the material functions, and that it is naturally suitable to step-by-step computer simulation. In this paper we apply the PHM to two dimensional (2-D) situations. To this end, we've developed a 2-D finite difference code in cylindrical geometry which is based on the PHM. We demonstrate the validity of our modeling by applying the code to a 2-D set-up developed for this purpose. The 2-D specimen is in the form of a disc of the test material compressed between two rigid metal anvils by a velocity-controlled Instron machine. We monitor the response of the viscoelastic disc in terms of the overall axial force history, and the axial stress component at the disc center. We get good agreement between theory and experiment.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241807
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    Deformation recovery behavior of a solid polymer after tensile yielding (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1429-1432 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The deformation recovery at room temperature of a polycarbonate after large tensile deformation and subsequent stress relaxation is measured as a function of time. The effect of the main parameters which affect the amount of recovered deformation is analyzed. This suggests a plot of the recovery versus time curves by means of proper coordinates which allow shifting of all curves towards a single master curve, thus indicating that most of the phenomena involved in the recovery process are taken into account.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760241810
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  • 156
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    Necking behavior of low-density polyethylene-isotactic polypropylene blends: A morphological investigation (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 264-267 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The tensile behavior of low-density polyethylene-isotactic polypropylene blends was investigated at room temperature. Neck formation and propagation along the whole length of the samples were observed for the whole range of composition. This behavior, which is not indicated by most data available in the literature, was examined in relation to sample morphology by scanning electron microscopy. The results of this investigation indicated some differences between the morphology of these materials and the morphology of blends which do not undergo necking propagation.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240406
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    Preface (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 291-291 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240502
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  • 158
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    The crystalline morphology of poly(vinylidene fluoride)/poly(methylmethacrylate) blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 311-318 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(vinylidene fluoride), PVF2, as well as blends of PVF2 with poly(methyl methacrylate), PMMA, develop a variety of crystalline morphologies at low undercoolings. Both the α and γ crystal forms grow from the melt and the former undergoes a solid-solid phase transition to the latter, though its morphology remains unaltered. Three melting temperatures which decrease with increasing PMMA content are observed. Hoffman-Weeks analysis shows the equilibrium melting points of the blends to be depressed. Using these equilibrium values, the thermodynamic interaction energy density is calculated to go from -5.40 × 106 to -2.96 × 107 j/m3 as the blend composition goes from 40.1 volume percent to pure PVF2. The band periodicity in the α form spherulites increases with crystallization temperature and PMMA content and it appears to be from a lamellar reorientation process with an apparent activation energy of 322 cal/mole. Electron diffraction patterns taken along the radial direction in a given spherulite reveal lamellar twisting which causes the banded appearance. Light scattering results suggest that the lamellar are formed into rod-like structures on a local scale but that on a larger scale they develop a disoriented spherulitic morphology.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/pen.760240505
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  • 159
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    Positional small angle X-ray scattering from flaws (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 373-375 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A simple theory of PSAXS (positional small angle X-ray scattering) has been developed and used to aid in the interpretation of PSAXS data from flaws. The importance of the various experimental parameters has been studied and an explanation offered for apparent magnification. A comparison between images created by assumed flaw structures and from actual flaws has been made. It is proposed that three dimensional imaging of flaws can be performed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240512
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    Morphology and properties of blends of polypropylene with ethylene-propylene rubberPresented in part before the 50th Anniversary Meeting of Chinese Chemical Society, Nanjing, P. R. C., September, 1982, and in part at the International Symposium on Phase Relationships and Properties of Multicomponent Polymer Systems, Capri, Italy, 1983. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 612-617 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Great attention has been paid to the toughening of isotactic polypropylene (PP) in recent years in order to make full use of this plastic. This paper presents the results of our study on the compatibility of PP with ethylene-propylene-diene rubber (EPT), polybutadiene rubber (PB) or styrene-butadiene rubber (SBR) through characterization of the blends' morphology, and on. the morphology and properties of binary blends of PP with EPT (EPT/PP) and ternary blends of PP, EPT, and polyethylene (PE) (EPT/PE/PP). Morphological structure of solution blends and the great improvement in low-temperature impact strength and other properties of the mechanical blends have shown the difference among EPT, PB, and SBR in compatibility with PP, the effectiveness of using EPT as PP's toughening agent, and the effect of EPT on EPT/PP blend as both toughening agent and compatibilizer. Addition of EPT to EPT/PP made interesting changes in morphology but no effect on properties was observed.
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    URL: http://dx.doi.org/10.1002/pen.760240814
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    Mathematical modeling of squashing flows of heated polymer particles (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 652-661 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A combination of shear and extension is encountered in the squashing flows of heated polymer particles. Extensional rate affects the non-Newtonian viscosity in determining the flow field in the squashing of cylindrical particles, but both the extensional and shear rates are equally important for disc-like particles.A viscous-type constitutive equation is used for simplicity. The solution of the momentum equations satisfying no-slip boundary conditions leads to a particle flattening equation that can predict flattening ratios of nonisothermal particles in terms of rheological parameters and dimensionless groups of process variables. Application of this analysis to roll fusing of toner particles in copiers is described in a companion article in this issue.
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    URL: http://dx.doi.org/10.1002/pen.760240907
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    Block polymers. Characterization and use in polymer blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 104-111 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer blends, because of the well-known immiscibility of polymers, generally show phase separation. Block polymers can be considered as simple models of two-phase systems. Because unlike segments are connected by covalent bonds, the phase separation is on a smaller scale and takes rather unusual forms. The types of block polymers of commercial importance are described with a consideration of the morphologies which result from particular compositions. Their use as solubilizing agents to increase the compatibility of the corresponding homopolymers is also discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240207
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    The composition-dependent glass transition: Relations between temperature pressure, and composition (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 135-143 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A new predictive relation between pressure and temperature changes on the glass-transition boundary is derived for random solutions. The isobaric version of this relation is integrated to recover a previous theory for the compositional variation of glass-transition temperatures. The isothermal form of the differential equation gives an equation for the compositional variation of glass-transition pressures. An enthalpic definition of the transition boundary provides a relation between excess enthalpies of mixing for the glassy and liquid states for the isobaric and isothermal transitions. Similarly, a definition of the boundary in terms of the solution volume provides a relation between excess volumes of mixing for these two states for the isobaric and isothermal transitions. The primary entropic equation for the composition-dependent isobaric transition gives two hierarchies of approximation, one of which is shown to be preferred for physical reasons. A parallel situation arises for the isothermal transition.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240211
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240301
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  • 165
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    Rheological properties of blown film low-density polyethylene resins (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 259-263 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Three blown-film-grade low-density-polyethylene (LDPE) resins were studied using different rheological techniques. Eccentric rotating disks (ERD), cone-plate viscometry, capillary rheometry, annular die extrusion, and non-isothermal stretching of a filament were used. The viscoelasticity of the melts was found to play a dominant role in the observed behavior. Extrudate appearance in annular flow, melt strength, and extensibility are affected by melt elasticity. A correlation was found between the maximum draw ratio of a filament stretched under non-isothermal conditions and minimum film thickness.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240405
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  • 166
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    Linear-low-density polyethylene melt rheology: Extensibility and extrusion defects (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 268-274 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper investigates three aspects of linear-low-density polyethylene (LLDPE) rheological properties: shear viscosity variations with shear rate and temperature, tensile behavior determined with an extensiometer, and extrusion defects. The differences in shear viscosity variation with shear rate and temperature between LLDPE and LDPE (low-density polyethylene) are shown. These differences, attributed to wider molecular weight distribution and to long chain branching (LCB) in LDPE, involve different extrusion behaviors. The lack of LCB in LLDPE can be demonstrated by comparison of the measured Newtonian viscosity with the value of the same parameter calculated from molecular weight distribution and composition law of Newtonian viscosities. The lack of LCB leads to good melt extensibility, which is shown by tensile properties of polyethylene melts determined with a non-isothermal extensiometer. The melt fracture phenomenon is studied because it promotes surface defects on bubbles in film application. Extrudate distortions are examined at the laboratory extruder outlet. This test shows differences between LLDPE and LDPE, but also between some LLDPE samples.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240407
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  • 167
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    Applications of a reaction-injection-molding process model in the analysis of premature gelling, demold time, and maximum temperature rise (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 428-434 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In this paper, we discuss a way to present results or practical interest for the reaction injection molding (RIM) process, such as guidelines to avoid premature gelling and to control demold time and maximum temperature rise. The results are presented as a set of graphs correlated using the relevant dimensionless groups of the process. Examples of applications of these graphs are given and discussed. The numerical calculations are done using the RIM process model developled by Castro and Macosko, which has been shown to agree with experimental results.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240607
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  • 168
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    High-temperature electrical conductivity and thermal decomposition of Sylgard® 184 and mixtures containing hollow microspherical fillers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 435-441 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The high-temperature electrical conductivity and thermal decomposition characteristics of Sylgard® 184 with and without hollow microspheres of glass, silica, and ceramic have been determined to 600 to 700°C in air and nitrogen environments. The materials are silicone-based dielectrics and are used as electronic encapsulants. Results show that a peak in the conductivity temperature dependence at ∼300°C results principally from volatilization of [Si(CH3)2O]n with some evolution of water, that oxygen accelerates decomposition, and that the microspheres may help form a network of interconnected conductive pathways in the residual material. There is a good correlation between thermal stability and temperature-dependent electrical properties.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240608
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  • 169
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240201
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  • 170
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    The disentanglement time of the craze fibrils under cyclic loading (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 820-824 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In a previous publication a breaking or disentanglement-time was defined for the fibrils in the craze at the tip of a steady-state moving crack. In this paper the case of a cyclic sinus loading is investigated, whereas in the previous one the case of a static loading was studied. In both cases the craze fibrils break due to a thermally activated process. The apparent activation energy corresponds to that of the secondary relaxation peak (b̃) in poly(methyl methacrylate). Under cyclic loading conditions the breaking time may be expressed as a time or as a number of cycles carried by the fibrils before breakage. It seems that the relevant parameter is the time rather than the number of cycles. At high frequencies and temperatures an hysteretic heating effect has been detected by means of the breaking-time of the fibrils.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241012
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  • 171
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    Dynamic X-ray diffraction studies of spherulitic poly-alpha-olefins in relation to the assignments of alpha and beta mechanical dispersions (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 361-372 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The dynamic tensile deformation mechanism of spherulitic poly-alpha-olefins, high-density polyethylene, isotactic polypropylene, and isotactic polybutene-1, was investigated by dynamic X-ray diffraction at various temperatures and frequencies in order to assign the α and β mechanical dispersions explicitly. The uniaxial orientation distribution function qj(ζj, 0) of the j-th crystal plane and its dynamic response Δqj′(ζj, 0) in-phase with dynamic strain were observed for several crystal planes, and then the orientation distribution function ω(§, 0, η) of crystallites (crystal grains) and its dynamic response Δω′(§, 0, η), also in-phase with the dynamic strain, were determined by a mathematical transformation procedure proposed by Roe and Krigbaum on the basis of the Legendre addition theorem. The temperature and frequency dependences of Δω′(§, 0, η) were analyzed in terms of a spherulite deformation model combining affine orientation of crystal lamellae with several types of preferential reorientation of the crystal grains within the orienting lamellae. The following assignments are made: (1) the a mechanical dispersion must be assigned to the dynamic orientation dispersions of crystal grains within lamellae involving two types of preferential rotations of the grains associated with lamellar detwisting mostly in the equatorial zone of uniaxially deformed spherulites and with lamellar tilting mostly in the polar zone of the spherulites. Both processes are intralamellar grain-boundary phenomena, and the former process of lamellar detwisting is hardly activated for polypropylene and polybutene-1 spherulites in contrast to polyethylene spherulites. (2) The β mechanical dispersion must be assigned to the dynamic orientation dispersion of the crystal lamellae behaving as rigid bodies unaccompanied by reorientation of crystal grains within the orienting lamellae. This process is an interlamellar grain-boundary phenomenon.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240511
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  • 172
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    Performance of gear pumps in polymer processingPresented at the Symposium “Milestones and Trends in Polymer Science and Technology - A Tribute to Turner Alfrey,” Midland, Michigan, June 7, 1983. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 398-402 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Within the past several years considerable interest has developed in the practice of retrofitting plasticating extruders with gear pumps. The primary motivation for this is to reduce surges and fluctuations in the extrusion rate, thereby improving product quality and reducing waste. It is shown that the effectiveness of a gear pump for this purpose is directly related to its volumetric efficiency, which depends upon the pump dimensions, the flow behavior of the polymer, and the operating variables of temperature, pressure differential, and pump speed. Experimental data on three thermoplastic materials using a pump having gear wheels of 36 mm diameter for both leakage and power are reported. These data have been correlated with semi-empirical equations.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240603
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  • 173
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    Preamble (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 69-69 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240202
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  • 174
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    Fluorescence techniques in the study of polymer colloids (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 87-97 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Applications of fluorescence techniques to the study of polymer colloids are reviewed, with emphasis on excimer and exciplex forming probes and fluorescence energy transfer processes. In these experiments non-aqueous dispersions covalently labelled with naphthalene or anthracene were examined by a variety of techniques in order to elucidate aspects of core morphology with a resolution of about 10Å. The current “concentric sphere” or “core-shell” model of colloid structure was found to be inconsistent with the results of the luminescence experiments. A new “microphase” model is proposed which overcomes these difficulties. In this model, the core structure is seen to be made up of phase-separated microdomains of core and stabilizer chains.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240205
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  • 175
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    Physical aging of poly(methyl methacrylate) in the nonlinear range: Torque and normal force measurements (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1138-1141 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Cylindrical specimens of poly(methyl methacrylate) (PMMA) were quenched from above the glass transition and subsequently tested in torsion. Torque and normal-force relaxation responses were recorded simultaneously. The experiments were performed at 40, 60, and 80°C, at increasing aging times and at deformations ranging from γ = 0.0027 to γ = 0.074. It was found at 40 and 60°C, that, contrary to the classical picture of aging, the small-deformation torque-relaxation curves could not be superposed by any combination of vertical and horizontal shifts. On the other hand, at 80°C, and in the nonlinear deformation range even at lower temperatures, the relaxation curves are superimposable simply by horizontal shifts, but as γ increases they involve decreasing values of the double-logarithmic shift rate. At the same deformation level, however, the shift rate for the normal force is significantly higher than is that for the torque over most of the γ range investigated.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241410
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  • 176
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    Correction (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1165-1165 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241503
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  • 177
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    Wood fibers as reinforcing fillers for polyolefins (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1166-1171 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Wood pulp fibers possess strength and modulus properties which compare favorably with glass fibers when the differences in fiber densities are considered. Softwood pulp fibers with fiber aspect ratios near 100 are readily dispersed into high-density polyethylene or isotactic polypropylene with the aid of carboxyic dispersing agents to form mixtures containing 50 weight-percent wood pulp which can be readily injection molded. The mechanical properties of the molded specimens were similar for all types of pulp including Kraft (bleached and unbleached), mechanical and chemical-mechanical pulps, waste pulps, and reclaim newspapers. Comparisons of the stiffness/weight efficiencies revealed that pulp composites equal or exceed the stiffness of most traditional materials of construction including steel, aluminum, glass-fiber composites, and talefilled polyolefins, while retaining a major material cost advantage. The measured strength values of the pulp composites were less than the theoretically predicted values due to the presence of voids created by the formation of volatiles during processing. Mechanical pulps which were available in dry form were preferred because of lower cost and ease of handling. Wood fibers are non-abrasive so that relatively large concentrations may be incorporated into polyolefins without causing serious machine wear during mixing and fabrication.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241504
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  • 178
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    Effect of the cooling rate in the formation of glass on the α and β relaxations of some amorphous polymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1202-1204 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It has been observed in dynamic mechanical measures that the range of temperatures in which relaxation properties are affected by the diminishing of the free volume has, as a lower limit the temperature at which the maximum of G″ or tgδ, corresponding to the β relaxation, occurs. In dielectric measures on polymers in which the β relaxation is not predominant over the α relaxation, this temperature range is scarcely affected by changes in frequency, whereas the peak shifts according to its activation energy. This fact leads to the conclusion that the decrease in free volume due to a slow cooling from a temperature above Tg mainly affects mobility of the main chains under Tg, without disturbing the groups that give rise to the secondary relaxations.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241509
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  • 179
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    Dynamic and steady-state rheological properties of linear-low-density polyethylene melt (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1215-1218 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Linear-low-density polyethylene (LLDPE) is steadily gaining importance in a wide variety of applications due to its excellent performance characteristics in the final product. The rheological properties of LLDPE in the dynamic and steady state are of great pragmatic importance and these have been studied in the present work. A correlation between the dynamic and steady-state rheological properties has been attempted and good agreement has been found.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241511
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  • 180
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    Liquid-liquid equilibria in polymer blends-molecular weight effects (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 601-607 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Flory's equation-of-state theory has been successfully used by several scientists to predict the qualitative nature of the liquid-liquid phase equilibria in polymer blends. This theory in its most simple form requires characteristic PVT parameters for each component plus an interaction energy parameter for the mixture. The melt titration technique was used to measure the miscibility of a series of polystyrene fractions (Mw = 4000 to 1,800,000) in low density polyethylene. Because the PVT properties of both of these polymers are well known, the experimental results could be compared with the predicted equilibrium compositions from Flory's equation-of-state theory using the interaction energy as an adjustable parameter. This comparison led to the conclusion that the interaction energy parameter may have some molecular weight dependence.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240812
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  • 181
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    Guest editor's note (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 623-623 
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    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240902
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  • 182
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    Computerization of wire insulating lines-An industrial approach (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 633-644 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The two main materials used for insulating wire are plastic and pulp. With the introduction of digital transmission techniques, there has been an increasing demand for improved cable quality, thereby stimulating an investigation of the insulating process in order to improve quality. The increasing availability of digital computers enabled mathematical models of the insulating process to be constructed, which together with experimental work, provided a basis for the installation of computerized control systems. This paper reviews three such models which were developed and are being used. These comprise a model for screw extrusion, a model for melt flow in the wire coating die, and a model for the subsequent cooling of the insulated wire (or cable). Relatively little work was done in the area of dynamic simulation of the insulating process and we found computer control systems could be relatively easily installed in production provided high level software process modules with interfaces to a high level programming language were available on the system. It was found that simplified control schemes were usually the most effective in production. Two computer control installations to illustrate this viewpoint are described - a multiline central computerized control system, and a single-line microprocessor-based system.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240905
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  • 183
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    Masthead (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240501
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  • 184
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    Microphase structure and properties of polyurethane/polyvinyl interstitial composites (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 293-310 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The morphology of two series of polyurethane/polyvinyl interstitial composites is characterized by scanning electron microscopy, small-angle light scattering, and small-angle X-ray scattering. Thermal and mechanical properties are measured using differential scanning calorimetry and dynamic mechanical analysis. The polyurethane networks examined are microphase separated segmented block copolymers. A variety of linear and network vinylic components are studied including polymethacrylonitrile homopolymer and copolymer, and polyacenaphthalene homopolymer and copolymer. The polyurethane and polyvinyl components phase separate during the in situ polymerization resulting in a three-phase morphology. Detailed small-angle X-ray scattering analysis provides measurements of phase mixing, domain spacings, and diffuse phase boundary thicknesses. A comparison of these parameters for parent polymers and composites reveals only slight differences; indicating that the microdomain structures of the phase-separated polyurethane networks are preserved in the composite. Appreciable molecular interpenetration of components is not observed. Dynamic mechanical loss measurements for several of the composites demonstrate the presence of loss processes occurring over extremely broad ranges of temperature. The strong mechanical interaction between components observed suggest that the urethane and vinyl phases may be bicontinuous in these materials.
    Additional Material: 27 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240504
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  • 185
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    Rheological and mechanical properties of ternary blends of linear-low-density polyethylene/polypropylene/ethylene-propylene block polymers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1319-1326 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of addition of an ethylene-propylene block polymer on rheological and mechanical properties of a linear-low-density polyethylene/polypropylene blend was examined. The samples were prepared by melt blending in a twin-screw extruder followed by injection molding. The single-, two- and three-component systems were treated the same way. The mechanical behavior of the blends was evaluated by means of tensile, and flexural, tests at 23 and -40°C. The capillary, elongational, and dynamic-flow measurements were performed at 190°C.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241709
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  • 186
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    Preliminary results on toughening a linear-low-density polyethylene using thermoplastic elastomers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1348-1353 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effects of several commercially available thermoplastic elastomers (TPE) on a gas-phase linear-low-density polyethylene (LLDPE) were studied using small-scale commercial-compounding techniques. The properties of blown films of these compositions were evaluated as a function of TPE type and composition and compared to unmodified LLDPE films. Ethylene/propylene elastomers had modest effects on the falling dart impact strength and machine-direction tear propagation resistance while polyisobutylene and styrene block copolymers had more significant effects on these properties.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241712
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  • 187
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    Panel and general discussion (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1359-1365 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241714
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  • 188
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    A basic study of orientation in poly(ethylene terephthalate) stretch-blow molded bottles (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1390-1395 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: A series of stretch-blow molded poly(ethylene terephthalate) bottles were investigated using measurements of birefringences (in plane and out of plane) and wide angle x-ray diffraction (WAXS) pole figures. Both bottles prepared in our laboratories and commercial bottles were investigated. Birefringences Δn13 and Δn23 of inside and outside surfaces of bottles were determined as a function of position along the length of the bottle (1-bottle axis, 2-hoop direction, 3-thickness direction). The Δn13, Δn23 for the inside surface of the bottles were found to be greater than those for the outside surface indicating heterogeneity through the thickness of the bottles. The WAXS studies indicate that the benzene rings in the polymer align parallel to the bottle surface. The chain axis in crystalline regions exhibit orientations close to equal biaxial orientation. Both Δn13 and Δn23 increased with inflation pressure.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241804
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  • 189
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    Predicting water diffusivity in elastomers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1417-1420 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: By the use of water absorption data (rate and equilibrium), the diffusivity of distilled and salt water through Neoprene, styrene-butadiene, and ethylene-propylene-diene elastomers was predicted. Activation parameters were calculated from the Arrhenius plots and were used to calculate heats of solution (all negative). Solubility coefficients (S) were calculated from permeability (P) and diffusion (D) coefficients. For all materials salt water showed a lower D than distilled water but a higher S and P.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241808
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  • 190
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    Electronic Resource
    Morphology of polyethylene-polypropylene blends (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 488-492 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The morphology of blends of high-density polyethylene (PE) and isotactic polypropylene (PP) was studied by mesans of optical and scanning-electron microscopy. In the range of 10 to 90 percent by weight PE, these blends are two-phase systems, the components of which crystallize separately into discrete phases. The presence of PE has a definite and pronounced effect on the crystalline structure of the PP, whose spherulitic structure becomes increasingly irregular and coarse with increasing PE content. The light transmission of these blends during melting and crystallization was also studied in an attempt to characterize them.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240707
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  • 191
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    Isothermal swell of extrudate from annular dies; effects of die geometry, flow rate, and resin characteristics1Some of the results contained in this paper were presented at the October 1982 meeting of the Society of Rheology in Evanston, Illinois.2The data in this paper are from the doctoral dissertation of N. Orbey, submitted in May of 1983. (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 511-518 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An experimental study was made of the effects of die geometry and extrusion velocity on parison swell for three high-density-polyethylene blowmolding resins. Four annular dies were used: a straight, a diverging, and two converging dies. Diameter and thickness swells were measured as functions of time under isothermal conditions and in the absence of drawdown. This was accomplished by extruding into an oil having the same density and temperature as the extrudate. It was observed that 60 to 80 percent of the swell occurs in the first few seconds and that equilibrium swell is attained only after 5 to 8 minutes have elapsed. The diameter and thickness swells appear to be independent phenomena, as the relationship between them depends strongly on die design. The ranking of the resins in terms of the magnitude of the swell was found to be the same for all die geometries and extrusion rates used.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760240710
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  • 192
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    Kinetics of crack tip craze zone before and during fracture (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 798-808 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Irreversible deformations form the main energy consumption routes for absorbing supplied energy and thus determine the resistance of materials to fracture. In many polymeric materials under mode-I loading conditions three regions of irreversible deformation behavior can be distinguished as a function of the stress intensity factor KI or strain energy release rate GI, respectively: no crack growth for Ki 〈 KIoslow crack growth for KIo 〈 KI 〈 KIcrapid crack propagation for KI 〈 KIc In the three regions the amount and geometrical extent of irreversible deformations may be different and the influence of time, crack speed, and temperature may generate different results.In this paper the influences of time and crack speed on the kinetics of the craze zone at the crack tip will be considered in some detail, with respect to results mainly obtained for poly(methyl methacrylate), PMMA, of high molecular weight under quasi-static loading conditions.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241009
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  • 193
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    Diffraction studies of craze structure (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 825-832 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Recent work using small angle scattering techniques to study craze structure is reviewed. Three different radiations, electrons, X-rays, and neutrons were used to study four problems in the area. These were (1) the structure of crazes in thin films, (2) the structure of a single craze/crack in a bulk material, (3) the effect of organic environments, and (4), the effect of mechanical fatigue on craze structures. It is shown that the high intensity of a synchrotron source permits the examination of the process of growth and breakdown of a single craze in polystyrene and also the study in real time of the short- and long-term changes during fatigue of crazes. The H/D neutron contrast effects for neutrons were used to study environmental crazes with the environment still present.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241013
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  • 194
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    Electronic Resource
    Craze development in poly(methyl methacrylate) during stable fatigue crack propagation (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 833-842 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: In order to obtain a more complete understanding of failure mechanisms in glassy polymers subjected to fatigue loading conditions, craze zone dimensions (i.e., length and thickness at the crack tip) were measured simultaneously with fatigue crack propagation data in poly(methyl methacrylate) (PMMA) by optical interferometry. Since the craze shape was observed to assume a wedge-shaped configuration similar to the one described by the Dugdale plastic strip model, crazing stresses were inferred on the basis of this model. When varying the stress ratio (R = minimum load/maximum load) of the applied cyclic load in the range from 0.1 to 0.7, it was found that both craze length and craze thickness are essentially independent of the R-ratio and can be correlated in terms of the maximum stress intensity factor only. On the other hand, significant variations in craze dimensions with test frequency occurred over the range from 0.1 to 250 Hz. The results are discussed in terms of the viscoelastic nature of the material and a competition between the effects of strain rate and hysteretic heating.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241014
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  • 195
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    A novel technique for the determination of high frequency equibiaxial stress-deformation behavior of viscoelastic elastomers (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 862-868 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Synthetic elastomers and elastormeric-like copolymers are now being utilized for a wide spectrum of biomaterial uses including primary structural applications such as pump bladders in artificial hearts and left ventricular assist devices (LVAD), leaflets in prosthetic heart valves, and vascular prostheses. In making fatigue lifetime measurements, as well as for predicting durability, it is essential to know the biaxial stress-deformation behavior at high strain rates (high frequencies) and at extension ratios at least as high as those encountered under performance conditions. This paper describes a technique for determining the high frequency equibiaxial stress-deformation behavior of elastomers. Measurements of material parameters are made at the high strain rates (or frequencies) at which accelerated biaxial flaw growth and fatigue experiments are performed and hence do not require correction for strain-rate dependence of material properties. Furthermore, the plastic deformation (creep) which occurs in the case of viscoelastic membranes is incorporated in the calculations; yielding the “true” values of the extension ratios. Experimental measurements were performed on urethane-based biomaterials using a tuned fluid oscillator which produces cyclic biaxial inflation of the elastomeric membranes clamped around the circumference. Up to moderately large equibiaxial deformations, the form of strain energy function derived from the Gaussian, network theory (or the first approximation to Rivlin's formulation of strain energy function) was found to adequately describe the stress-deformation data. This in turn permits accurate calculation of the tearing energy under biaxial conditions, which is a prime requisite for predicting biaxial fatigue lifetime distributions.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241105
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  • 196
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    Plastic deformation and tearing in high density polyethylene blown films (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 895-907 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polymer films produced by tubular film blowing have a unique morphology that results from the large elongational flow in melt draw down and biaxial orientation due to bubble blow-up. Three high density polyethylene (HDPE) blown films were produced under similar processing conditions from resins which varied principally in molecular weight (MW) and molecular weight distribution (MWD). Scanning electron microscopy (SEM) showed that the lower MW and narrower MWD resin produced film which had a uniaxial orientation of stacked lamellar crystals. The higher MW (HMW) and broad MWD resins produced films consisting of a network of nearly orthotropically oriented lamellar stacks. Greater high molecular weight fraction (MW 〉 106) in the resin resulted in more random orientation. The influence of these different structures on properties was studied by examining the plastic zone formation at crack tips and uniaxial tensile deformation with the SEM and comparing them to the macroscopic stress-strain behavior. A continuous deformation of the network structure was observed in the HMW films. Lamellar deformation occurred primarily in regions of stacks oriented parallel to the tensile axis. Macroscopic yield occurred at 6 to 10 percent strain via a shearing and opening the lamellar crystals. Irreversible deformation occurred from ≃50 to 400 percent strain by transformation of the oriented lamellae to microfibrils. Eventually all the lamellar stacks in the network become aligned with the tensile axis. This process was found to improve the tear resistance in the crack propagation experiments. The lamellar stacks in the network orient perpendicular to the crack independent of crack propagation direction, insuring a more uniform transmission of stress and preventing local yielding. The tensile modulus, yield stress, and ultimate strength were highest in the film containing more high molecular weight polymer.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241109
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  • 197
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    Kevlar 49 composite performance: Dependence on thermoset resin microstructure (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 930-935 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Molecular structures for cured, thermoset resins have been examined by analyses of resin extracts by gel permeation chromatography. Numerical interpretation of leached oligomeric fractions coupled with kinetic reaction theory yields microscopic estimates of the network's structure, including crosslink average molecular weight. Leached monomeric fractions describe extent of cure. Analyses of test data incorporate irreversible, mechanical deformations for neat resin castings and for filament wound, Kevlar 49 composites. Heat distortion temperatures correlate with crosslink architecture. Short beam shear strength data for naval ordinance laboratory rings and pressure vessel burst performance are examined in terms of the resin's molecular structure. Variations in resin cure observed by positive feedback via chromatography indicate fluctuations in extent of crosslink development. Test specimen performance correlates with these microscopic, molecular distributions. Resin applications include filament wound composites for the aerospace industry, anhydride cured epoxies, and amine cured epoxies. The former resin is an elastic body at ambient test conditions. A third resin, a crosslinked resin of 1,2 polybutadiene/t-butylstyrene, is in final developmental stages and may exhibit a higher degree of viscoelastic behavior.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241113
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  • 198
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    Non-isothermal flow of a molten polymer in a coat-hanger die (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 980-987 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The non-isothermal flow of a power-law fluid in a coal-hanger flat die is studied. Equilibrium and thermal equations are solved by using an iterative finite difference method. The pressure distribution, the flow lines, the residence time distribution, the temperature distribution, and the flow uniformity at the end of the die are obtained, with a stress on the effect of thermal regulation and of temperature dependence of the viscosity.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241207
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  • 199
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    Thermodynamics of polymer solutions, especially poly(dimethyl siloxane) solutions (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1219-1226 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: An improved non-random free-volume theory of polymer solutions is presented. It is based on Flory's Equation-of-State theory which is modified to account for differences in the size of core volumes of segments in pure liquids and in solution. In addition, it is corrected for non-randomness through Guggenheim's Quasi-Chemical approach. The theory is tested against experimental results on heats of mixing, volumes of mixing, and χ interaction parameters of poly (dimethyl siloxane), polyisobutylene and natural rubber solutions with gratifying results. Relations with existing similar theories are discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241602
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  • 200
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    Manufacture of urea-formaldehyde concentrates using a gas-liquid technology (1984)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1245-1248 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The performance of a laboratory packed-column for the manufacture of urea-formaldehyde (UF) concentrates is analyzed. Gaseous formaldehyde was generated by the thermal decomposition of paraformaldehyde in a carrier nitrogen stream. The UF solution was continuously recirculated through a glass column filled with Raschig rings. No pH control was necessary when the operation was started using a solution with a F/U molar ratio higher than 3.5 to 4. Otherwise, insoluble resins appeared during the operation. The formaldehyde absorption rate was controlled by the gas phase resistance. The vapor composition in equilibrium with a typical UF concentrate is provided as a function of temperature.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760241606
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