The effects of chemical structure and synthesis method on photo degradation of polypropylene

摘要

The effects of chemical structure and synthesis method on the photodegradation behavior of polypropylene (PP) were investigated in injection-molded samples exposed to ultraviolet radiation (UV) at 60degreesC. For this purpose, three PP samples with different chemical structures were chosen: two homopolymerized PP samples (H2P, synthesized by bulk polymerization; whereas H2P was synthesized by Ziegler-Natta catalyst) and copolymerized PP sample (CP). The photodegradation was characterized by melt flow rate and mechanical properties and Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The results showed that CP possesses the most superior resistance to UV-irradiation, followed by H2P and then H1P, which indicates that copolymerization with a small amount of ethylene monomer is an effective approach to obtain high stability of PP to UV-irradiation, and synthesis methods of PP play an important role in the resistance to UV-irradiation. Moreover, the effect of photodegradation on the thermal behaviors of H,P was also investigated using X-ray diffraction, differential scanning calorimetry, and dynamical mechanical thermal analysis. (C) 2004 Wiley Periodicals, Inc.