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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 11 (1967), S. 2325-2330 
    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 effect of thermal history on the melting behavior of several linear polymer and copolymers of ethylene has been studied by using a Perkin-Elmer DSC-1 differential scanning calorimeter. Samples of film were heated above their melting point and then cooled at various rates in order to establish a known thermal history. During melting, homopolymers showed one peak and the copolymers two peaks in the DSC scan. The positions and relative sizes of the peaks were dependent on the prior cooling rate. It is suggested that two crystal types occur in the case of copolymers because of entanglements in the branched segments of the molecules. The position of the lower melting endotherm in blown films suggests that cooling rates of about 500°C./min. are achieved in this process.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 12 (1968), S. 547-555 
    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: Changes in flow properties of polyethylene resins have often been observed during processing operations. Studies in this laboratory show that melt viscosity of polyethylene normally increases when the resin is heated in a compression mold at temperatures below 300°C. At the same time, the solution viscosity actually decreases in some cases. During extrusion, on the other hand, both melt viscosity and solution viscosity are shown to decrease. In addition, the logarithm of melt flow rate is seen to deviate markedly from the expected linear dependence on reciprocal of absolute temperature. The results suggest that both crosslinking and chain-scission reactions occur during processing, the former predominating at low or zero shear, the latter at high shear.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 14 (1970), S. 1-9 
    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: Dissolution of sulfur-cured, carbon black-loaded copolymers and their blends with cis-1,4-polybutadiene (PBD) are brought about by boiling with o-dichlorobenzene which contains a small amount of 2,2′-dibenzamidodiphenyl disulfide. The resulting slurries are subjected to a sequence of separations which include high-speed centrifugation to remove solids, and solvent precipitation followed by filtration to isolate the precipitates. The precipitates are washed with solvent to remove soluble organic materials followed by carbon disulfide washing to dissolve the polymers. Cast films of the polymers are obtained by evaporating the carbon disulfide washings onto sodium chloride discs. The infrared spectra of the cast films of these preparations are very similar to those of their respective polymers prior to loading and curing. Calculations for relative concentrations of bound styrene and PBD microstructures permit nominal identification of the kinds of styrene-butadiene rubber and the amounts of cis-1,4-PBD used in a cured rubber formulation. Absorption bands used are near 3.35 μ for cis-1,4-PBD, 6.65μ for bound styrene, 10.35 μ for trans-1,4-PBD; and 11.0 μ for vinyl-1,2-PBD. Efforts are being made to improve the data by using a grafting infrared instrument and also to extend the calibrations to include other rubber blends.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 7 (1975), S. 554-556 
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H and 13C NMR spectra of cis- and trans-2,3-dimethyloxetane have been re-examined and the published NMR assignments shown to be in error.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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