A procedure is described for the preparation of a block copolymer with A‐B‐A sequences in which ω‐ω′‐dihydroxy‐poly‐(ethylene glycol) is inserted between two polymeric monoacidic chains of polycaproamide and bonded to them by means of ester links. The resulting material was characterized. The copolymer is isomorphous with the polycaproamide. Thermal treatments induce a crystalline transition γ → α as in polycaproamide. The influence of the moisture content on the glass transition temperature and on the storage modulus is discussed.
A precipitation method of molecular weight fractionation allows the fairly rapid characterization of poly(ethylene terephthalate). An arbitrarily defined parameter can express the degree of macromolecular homogeneity. The fractionation parameter is also useful for the control of the polymerization process and the constancy of the polymer properties.
SynopsisThe polymerization of p,B'dimethyl-8-propiolactone with various catalysts was investigated. A detailed stjudy on the heterogeneous polymerization initiated by triethyl aluminum wa$ carried out. A reaction mechanism is suggested on the basis of chemical analysis of the polymer.
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