Study of thermo-oxidative degradation of molten state polypropylenes with a variety of tacticities

Abstract

Thermo-oxidative degradation of polypropylene(PP)s with a variety of tacticities was investigated in terms of various degradation factors, such as catalyst residue in the PP and molecular weight of the PP. Heat treatment was typically carried out in air at 200°C for 30 min, where the PP powder was converted to a molten state within several minutes. The catalyst residue and molecular weight had a slight influence on the thermo-oxidative degradation of isotactic PP (iso-PP). The thermal stabilities of three PPs [iso-PP, atactic PP (ata-PP), and syndiotactic PP (syn-PP)] having similar molecular weights were investigated under the same conditions. Iso-PP was degraded drastically in air compared with ata-PP and syn-PP. Thus, it was found that the influence of the tacticity was significant compared with that of the catalyst residue and molecular weight.