Effect of Thermal History on Structure and Impact Fracture of Polypropylene Impact-Copolymer (ICP)

摘要

The effect of multiple processing on molecular structure, morphology and impact fracture behavior of polypropylene impact-copolymer (ICP) prepared using 3 different polymerization technologies was investigated. During multiple processing, significant reduction of the iPP homopolymer molecular weight has been observed, with its extent directly proportional to the amount of catalyst residue. As a result, the crystalline morphology of the homopolymer phase has been altered. Significant molecular degradation of the ethylene-propylene rubbery phase, has not been detected under the extraction conditions used. Properties of the ICPs were controlled by the content of the EPR phase. LEFM with contained yielding can be used to analyze G_c data measured at -20°Cwhile EPFM has to be used for data measured at 23°C where significant plastic deformation has developed before fracture.