Highly active thermally stable beta-nucleating agents for isotactic polypropylene

Varga, József and Mudra, I. and Ehrenstein, G. W. (1999) Highly active thermally stable beta-nucleating agents for isotactic polypropylene. JOURNAL OF APPLIED POLYMER SCIENCE, 74 (10). pp. 2357-2368. ISSN 0021-8995

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Abstract

Calcium salts of suberic (Ca-Sub) and pimelic (Ca Pim) acids were synthesized and implemented as in different grades of isotactic polypropylene (IPP). Propylene homopolymer, as well as random and block copolymers containing these additives, crystallized iPP into pure or nearly pure beta modification in the isothermal and nonisothermal crystallization experiments. Recently, Ca-Sub proved to be the most effective beta-nucleating agent of iPP. The Ca-Sub nucleating agent widens the upper crystallization temperature range of pure beta-iPP formation up to 140 degrees C. In this study the effect of the these additives on the crystallization, melting characteristics, and structure of the PP were studied. The degree of crystallinity of beta-iPP was markedly higher than that of alpha-iPP. A widening in the melting peak of the samples crystallized in a high temperature range was first observed and discussed in regard to literature results of the same phenomenon for alpha-iPP. The morphology of the beta-iPP samples was revealed by scanning electron microscopy. Independent of the type of polymer or nucleating agent, hedritic structures were found in the early stages of growth of the beta-spherulites. (C) 1999 John Wiley & Sons, Inc.

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