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  • Polymer and Materials Science  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 28 (1958), S. 445-447 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 10 (1953), S. 489-498 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The complete characterization of a branched polymer involves many factors, the most difficult to assess being the average number of elementary linear portions, or branches, of which the polymer is composed, the degree of polymerization of the branches and the extent of cyclic structure formation. A method of analysis of branched polymers is proposed which should be applicable to polymers of any polyfunctional monomer the unsaturated groups of which are separated by saponifiable links. The method is based on the measurement of degree of polymerization and residual unsaturation of the polymer followed by saponification and determination of degree of polymerization of the resulting polymer, and involves the assumptions that branching in the polymer occurs only by the sharing of a monomer unit by two or more linear portions or branches depending on the number of double bonds in the monomer and also that the average degree of polymerization of the branches remains unchanged by the saponification treatment. Evidence from experiments on the saponification and re-esterification of poly(allyl acetate) and poly(allyl benzoate) indicates, that, in the case of diallyl esters, the above conditions are satisfied. The technique was therefore applied to three polymers of diallyl phthalate, and in each case the average number of chains and degree of polymerization of the chains were estimated. Evidence of considerable extents of cyclic structure formation was found, each individual branch in the polymers consisting of approximately fourteen diallyl phthalate units, six of which are doubly reacted. It is suggested that the existence of extensive formation of cyclic structures may be partly responsible for the poor correlation of predicted with actual degrees of conversion at gelation in polymerizations involving multifunctional monomers.
    Additional Material: 4 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 18 (1955), S. 335-349 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recent investigations have shown that cyclization or intramolecular crosslinking plays a major part in the polymerization of diallyl phthalate, and an extension of the network theory of gelation to allow for this led to satisfactory agreement between actual and predicted degrees of conversion at gelation for this monomer. It became important, therefore, to find whether satisfactory agreement could be obtained for other systems, and a detailed examination of the polymerization of the diallyl esters of isophthalic, terephthalic, oxalic, and sebacic acids has now been made. In all of these cases gelation occurs at a conversion higher than the predicted value, the discrepancy being considerably greater than can be accounted for by experimental error. Complicating factors in the interpretation of the experimental results are shown to be absent and it is concluded that cyclization in the poly(diallyl esters) does not affect gelation in the manner expected from theory, and that the satisfactory correlation in the case of diallyl phthalate is fortuitous. It is shown, in the case of the isomeric phthalates which are considered strictly comparable, that all three systems gel at the same degree of conversion, although the ortho ester polymer has considerably fewer pendent allyl groups available for crosslinking and is also of a lower chain length than the other two polymers. This fact seems irreconcilable with the network theory of the gel point as it exists at present. The results are discussed in relation to Walling's diffusion control theory, and although the constancy of conversion at gelation is consistent with the predictions of this theory, supporting evidence regarding molecular complexity is lacking.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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