Using crystallisation fractionation to monitor thermo-oxidative degradation of impact poly(propylene) copolymers
ICPPs are complex materials that contain various ethylene/propylene copolymers in addition to the majority poly(propylene) phase. To understand their molecular structure, multiple fractionation and analysis techniques are used. In this study, TREF and CRYSTAF are used to study the difference in the thermo-oxidative degradation of two grades of ICPPs with different ethylene contents. Direct correlations are drawn between the carbonyl index, molecular weight and crystallisability at various stages of degradation. The higher ethylene content sample shows increased thermal stability. This is due to the fact that the ethylene/propylene fraction is more stable due to the higher comonomer content and lower isotacticity as well as due to the higher amount of this fraction in the material. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.