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  • 1
    Electronic Resource
    Electronic Resource
    Crystallization of bisphenol-A polycarbonate induced by organic salts: Chemical modification of the polymer. III. Reaction mechanism (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 493-507 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the presence of a sodium arylcarboxylate or arylphenoxide, bisphenol-A polycarbonate (PC) undergoes complex chemical modifications at high temperatures. The reaction mechanism is similar to the one previously established for model systems. Initially, the salt reacts with the carbonate groups of the polymer. This lowers the number-average molecular weight and produces ionic chain ends of the phenoxide type. A fast transesterification reaction is then induced by a continuous exchange between the phenoxide and the carbonate groups, affecting the molecular distribution until an equilibrium is attained. In the presence of CO2, the phenoxide-terminated PC undergoes further chemical modifications (formation of phenyl salicylate and phenyl phenoxybenzoate groups) leading to progressive crosslinking of the polymer.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180230307
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Crystallization of bisphenol-A polycarbonate induced by organic salts; physical aspects. I. Crystallization rate, melting behavior, and morphology (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 751-770 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The presence of organic acid salts in bisphenol-A polycarbonate (PC) completely modifies the crystallization mechanism, the melting behavior, and the morphology of the polymer. Organic salts are not ordinary nucleating agents for PC since they react with the polymer, producing metal phenoxide chain ends. On reaction, abundant instaneous nucleation is induced. The seeds are likely to be polymer crystalline fragments preexisting in the melt. The phenoxide chain ends significantly increase the growth rate of the crystalline phase. Melting points and enthalpies of fusion are unusually high, suggesting a high degree of crystalline perfection. Thick multilamellar crystals, which are likely to contain chains in extended configuration, are observed by electron microscopy. No trace of spherulitic morphology is found. The chemical instability of PC containing ionic chain ends is also shown to seriously affect the crystallization rate, the maximum degree of crystallinity, and the melting point.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180230411
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Crystallization of bisphenol-A polycarbonate induced by organic salts: Chemical modification of the polymer. I. Model reactions (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 343-353 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The chemical modifications induced in diphenyl carbonate (DPC) by sodium arylcarboxylates between 200 and 250°C were studied to model the behavior of bisphenol-A polycarbonate - salt systems. Reaction between the salt and DPC produces sodium phenoxide, the phenyl arylcarboxylate corresponding to the salt, and carbon dioxide. The two latter compounds probably result from the decarboxylation of an unstable intermediate compound, viz., a mixed carboxylic carbonic anhydride. CO2 and sodium phenoxide act as catalysts transforming DPC into phenyl salicylate via the formation of a small amount of sodium salicylate. Electrophilic acylation of sodium phenoxide by DPC is another possible but minor source of phenyl salicylate. Above 250°C, phenyl salicylate becomes unstable and pyrolyzes into o-phenoxybenzoic acid, which is immedicately esterified in the presence of DPC into phenyl o-phenoxybenzoate. In DPC + sodium o-chlorobenzoate systems, reaction between phenyl o-chlorobenzoate and sodium phenoxide is another source of phenyl o-phenoxybenzoate.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180230209
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Crystallization of bisphenol-A polycarbonate induced by organic salts: Chemical modification of the polymer. II. Model reactions (1985)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 355-366 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the presence of sodium o-chlorobenzoate, bisphenol-A diphenylcarbonate (BADPC) undergoes complex chemical modifications from 170°C. Reaction between BADPC and minute amounts of salt produces sodium phenoxide end groups which undergo a fast exchange reaction with the carbonate groups of BADPC. In a closed system, an equilibrium molecular weight distribution is progressively attained which agrees fairly well with the one predicted from a simple model based on Bernoulli statistics. In an open system, the equilibrium is continuously displaced by the evaporation of volatile diphenyl carbonate. This leads to a steady increase of the molecular weight.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1985.180230210
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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