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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 2049-2054 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Thermally initiated crosslinking reactions have been studied in a linear low-density polyethylene, and an ethylene - propylene rubber. The polymers contained conventional thermal stabilizers or one of three surface-coated rutile pigments. Enthalpies of crosslinking and reaction kinetics depended on the degree of terminal vinyl unsaturation in the polymers, that characteristic being greater in the rubber than in the polyethylene. The presence of thermal stabilizers did not exert any measurable influence on measured parameters of the crosslinking processes. The effects of rutile varied, depending on their surface acidity or basicity, as determined from chromatographic measurements. Basic rutile was found to reduce heats and to slow rates of reaction, while acidic rutiles did not affect the reactions. These observations may be attributed to interaction between the basic pigment surface and acidic moieties involved in the crosslinking reaction. © 1992 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 54 (1994), S. 743-752 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 chromatographic data have been obtained for polystyrene, polycarbonate, and two substituted amines used as additives in the polymers. Surface energies have been determined and evaluations made of acid/base interaction parameters and Flory-Huggins χ values for the surface bounded interphase. It was shown that acid/base considerations are implicated in the miscibility of these polymer/additive systems. Surface energy analyses showed that surface and bulk compositions in blends differed whether or not the blend components were miscible. Composition differences were the result of thermodynamic drives to minimize surface free energy. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 56 (1995), S. 51-56 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 of alkanes has been used to assess the degree of fusion of rigid polyvinyl chloride (PVC) extrudates. The relative degree of fusion is provided by ratios of the retention volumes of the alkane probe molecules in the bulk of the PVC. This method is nonintrusive and can be used to measure degree of fusion quantitatively if a completely fused reference material can be provided. The present analysis involves evaluations of the contributions to the overall retention volume of the alkane probes, resulting from adsorption and from bulk diffusion. The diffusivity of the alkanes was clearly dependent on the processing history of the PVC extrudate. A direct variation was observed between the size of the diffusing molecules and their residence time as adsorbates on the polymer surface. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 721-727 
    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: Pyrolysis of polymer wastes appears to be a suitable means of dealing with an increasingly important environmental problem. To provide background on the pyrolytic behavior of wastes, model mixtures of polyethylene and polystyrene have been pyrolyzed in various gas phases including nitrogen and carbon monoxide, at atmospheric and at reduced pressures and at temperatures from about 300-900°C. When the pyrolyzing temperature is attained by gradual heating, and when pyrolysis occurs at pressures in excess of about 200 torr, the process occurs as if each component were present alone - that is, no evidence for component interaction was noted. In these cases, the known mechanisms for pyrolysis of the pure polymers can be applied to the behavior of mixtures. Complicating effects due to interactions between the starting polymers, or among the pyrolysis products, were observed in low pressure pyrolysis (≲20 torr); further, it was shown that the balance of pyrolysis products depends on rates of attaining the pyrolyzing temperature, more rapid rates favoring the production of carbon-rich solid residues of possible use as carbon blacks. More detailed understanding of pyrolytic processes in polymer mixtures is needed to permit selection of conditions producing the optimum balance of useful products.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 19 (1979), S. 900-906 
    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: Blends of linear polyethylene and ethylene-propylenediene elastomer, representing the entire composition range, were prepared under various conditions of shear intensity. It was found that both viscoelastic flow parameters and mechanical properties at large deformation respond strongly to variations in shear history of material preparation. Mechanical degradation of the polymers not being detected, it is postulated that property variations are due to morphological effects related to domain sizes of the two components and to the ease of molecular diffusion across domain boundaries. Thus, mechanical properties develop over finite times of mixing, consistent with the attainment of steady states in domain sizes. Maximum sensitivity of mechanical properties to mixing variables is found for 50/50 blends of the polymers, which have maximum interdomain contact areas. It appears feasible to develop desired balances of flow and mechanical properties in such polyblends through the close control of component dispersion processes.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 129-134 
    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: Polypropylene, polystyrene, EP (ethylene/propylene) rubber, and bromobutyl rubber were blended under standardized conditions and the sizes of minor phase domains determined by Quantimet analysis. Dispersion effectiveness was found to depend on the melt viscosities of components under mixing conditions and on their “compatibilty” as inferred here from surface-tension data. Dispersion was optimized when components wet readily at contact surfaces and when melt viscosities were similar. Shear heating during dispersion appeared to offer an empirical index of component compatibilty. Apparent melt viscosities of the blends further reflected the component compatibility factor.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 539-543 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 18 (1974), S. 2501-2508 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Calorimetrically determined integral heats of solution and swelling ratio measurements carried out on extrudates of low-density polyethylene blended with Surlyn ionomer and ethylene-ethyl acrylate copolymer provide independent evidence for the redistribution of components as a result of extrusion. Although this evidence for “migration” supports earlier data for extrusion-triggered molecular redistribution in polyethylene, the present data further suggest that the effect may be due at least in part to the tendency of crystallizable polydisperse polymers to form cohesively weak boundary layers upon cooling from the melt. Thus, molecular redistribution effects may be expected in the processing of polyethylene and related thermoplastics but would not be pronounced in the extrusion of amorphous, narrow molecular weight distribution polymers, e.g., polystyrene.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 1025-1034 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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: Gas-liquid chromatography (GLC) has been applied to the study of thermodynamic interactions in poly(vinyl chloride) (PVC) plasticized by di-n-octyl phthalate (DnOP). A number of vapor-phase “probes” were used to evaluate the Flory-Huggins thermodynamic parameter for the PVC-DnOP interaction in stationary phase mixtures of the components which covered the entire composition range. Experiments were carried out in the temperature span of 100-130°C. The interaction parameter was strongly negative, indicating high PVC-DnOP compatibility, up to 0.25 volume fraction of plasticizer. It then became less negative and finally positive at 0.55 volume fraction of DnOP, suggesting a lower compatibility limit. The composition dependence of the interaction parameter and its apparent variation with the chemical nature of the vapor-phase probe may reflect a nonrandom solution of the probe in the stationary phase and/or non-random mixing of PVC-DnOP, particularly at DnOP contents in the limited compatibility range. Evaluations of the influence of DnOP on zero-shear melt viscosity and Tg of compounds indicate that both thermodynamic interactions and volume-of-dilution effects must be taken into account in assessing the effectiveness of the plasticizer.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 2675-2690 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    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 complex relative premittivity K*(ω) of polymer-mica composites has been studied in the frequency range extending from about 10-2 to 107 Hz. Microwave plasma treatment in ethylene of the mica flakes leads to significant alterations of K*(ω) for the matrix polymers used - polyethylene, polystyrene, and a mixture of these two polymers. The origins of the dispersion characteristics were investigated using a series of polyethylene samples containing up to 50 wt-% of untreated mica. Comparing experimental results with theoretical analyses of the Maxwell-Wagner-Debye-like interfacial polarization effect, it is possible to identify two major contributions to K*(ω): a Debye-like dispersion centered near 102 Hz and a charge-diffusion mechanism which contributes primarily at low frequencies (≲10 Hz).
    Additional Material: 7 Ill.
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