Photodegradation of Polypropylene with sorbitol-based nucleating agent

Abstract

The paper deals with the effects of nucleation on photodegradation of isotactic polypropylene. The starting polymer was modified by a specific alpha-nucleating/clarifying agent Millad 3988 based on 1,3;2,4-bis(3,4-dimethylbenzylidene) sorbitol. Several concentrations were applied. Samples prepared by compression moulding were then exposed to UV-irradiation. Infrared spectroscopy showed that the degradation kinetics is similar for all the samples. Melting and crystallization behaviour of irradiated samples was followed using a differential scanning calorimetry. In all cases UV-irradiation led to decrease of melting/crystallization temperature as a result of polymer degradation. The surface cracking was observed using polarized light microscopy. The network of the surface cracking was significantly different for neat and nucleated samples.