English Abstract

Stabilization of Polypropylene by the Control of Primary Structure Hisayuki NAKATANI Department of Applied and Environmental Chemistry, Kitami Institute of Technology, Kitami, Hokkaido, Japan Minoru TERANO School of Materials Science, Japan Advanced Institute of Science and Technology, Nobi, Ishikawa, Japan Nippon Gomu Kyokaishi,(2006),79(9),440-442 General Review in Japanese Abstract Thermal oxidative degradation behavior of isotactic polypropylene (iPP) with various degree of isotacticity was studied based on the activation energy (E) data obtained by thermogravimetric analysis (TGA). The E value displayed a negative proportion to the content of meso pentad fraction (mmmm). Since the value of mmmm was directly related to polymer chain conformation, the E value was thought to have close connection with the concentration of 3 helix conformation in the iPP. The E changes would be caused by the competition between uni- and bimolecular hydroperoxide decomposition, which was controlled by the concentration of 3 helix conformation. In conclusion, this result suggested that the stability of iPP could be controlled by the primary structure such as isotacticity. Keywords: Polypropylene, Thermal Oxidative Degradation, Tacticity, Temperature Rising Elution Fractionation, Primary Structure

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