New Approaches for the Development of Highly Stable Polypropylene

摘要

Effects of primary structure on the degradation of polypropylene (PP) were studied using PPs having a variety of tacticities or a random ethylene sequence with the aim of improving the stability of PP. Thermal stabilities of isotactic, atactic and syndiotactic PPs (iPP, aPP and sPP) having similar molecular weights were investigated in terms of stereoregularity under the same conditions. The sPP showed the highest stability, suggesting that the racemic structure of the main chain interferes with the chain reaction of radical species. Moreover, iPP was prepared to evaluate the thermal stability with a random ethylene sequence (ethylene-propylene random copolymer: rPP). The rPP was more stable than iPP. The existence of the ethylene sequence in the main chain was found to be effective in achieving high stability.