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  • 1
    Electronic Resource
    Electronic Resource
    Rheo-optical studies of the nature of the α mechanical loss mechanism of polyethylene (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 1891-1939 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dynamic x-ray diffraction and dynamic birefringence techniques are employed to determine the nature of the molecular motions associated with the α mechanical loss processes for low-density polyethylene. The results indicate that the low-temperature part of this loss (designated α1) is associated with an interlammellar “grain boundary” slip process while the higher temperature process (α2) involves intracrystalline motion and plasticity of the crystal itself. The activation energy for α1 determined by x-ray response is 25-30 kcal/mole, while that for α2 is 30-60 kcal/mole. The findings are consistent with dynamic infrared and dynamic light-scattering results which indicate that the motion of amorphous chains is closely correlated with that of the crystals. The relative contributions of amorphous and crystalline regions to the birefringence are dependent on the thermal treatment of the sample. The effect of static strain on the dynamic response indicates that crystal orientability is first increased with strain, probably because of splaying apart of lamellae, is subsequently decreased because of the restrictions of interlamellae tie chains, but then increases again as the spherulites are destroyed at high strain. The static strain reduces the orientability of amorphous regions.
    Additional Material: 29 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.180111004
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  • 2
    Electronic Resource
    Electronic Resource
    Copolymerization of tetraoxane with styrene catalyzed by BF3·O(C2H5)2 (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 1937-1949 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The copolymerization of tetraoxane with styrene catalyzed by BF3·O(C2H5)2 was studied at 30°C. to determine whether a cyclic monomer can copolymerize with a vinyl monomer. The formation of the copolymer was confirmed by elementary analysis of both benzene-soluble and benzene-insoluble fractions of the polymer obtained. It was found by gas chromatography that a fairly large amount of 4-phenyl-1,3-dioxane and a small amount of trioxane were formed in the present system, in addition to polymers. Roughly a third of the total amount of the monomers reacted was consumed in the formation of methanol-insoluble polymer, a third for 4-phenyl-1,3-dioxane, and another third for trioxane and unknown products which could not be indentified. The formation of these cyclic compounds during the copolymerization may be explained in terms of a back-biting (or intramolecular transacetalization) reaction. The cationic reactivity of tetraoxane was found to be similar to that of styrene on the basis of both the consumption rate of each monomer in the copolymerizing system and the composition of the methanol-insoluble polymer obtained.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150050811
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Copolymerization of trioxane with styrene catalyzed by BF3·O(C2H5)2 (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 1927-1936 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It was determined whether trioxane, a cyclic formal, can copolymerize with styrene, a vinyl monomer, in the presence of BF3·O(C2H5)2 catalyst at 30°C. The methanol-in-soluble fraction after extraction with benzene was found to contain the copolymer of styrene and trioxane, thus demonstrating that trioxane can copolymerize with styrene In this case the amount of the methanol-insoluble polymer was less than that of the total monomer consumed, as determined by gas chromatography. This was found to be caused partly by the formation of the cyclic oligomer, 4-phenyl-1,3-dioxane. The relative reactivity of styrene was qualitatively found to be larger than that of trioxane, not only from the rate of monomer consumption but also from the composition of the methanol-insoluble polymer obtained. In a nonpolar solvent the reactivity of trioxane increased, and the difference in reactivity between the two monomers decreased. Indeed, an apparent monomer reactivity ratio might be obtained from the relationship between the monomer composition and the monomer consumption rate or the composition of the methanol-insoluble polymer, but it did not have a quantitative meaning because of the complexity of the copolymerization reaction.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150050810
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    Paper (German National Licenses)
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