gamma-ray-induced degradation: A comparative study for homo- and copolymers of polypropylene

Disposable medical supplies are currently made of polypropylene, which are conveniently sterilized by exposure to gamma-rays. However, the homopolymers (HP) and random copolymer (CP) of polypropylene, when exposed to high-energy gamma-irradiation, undergo oxidative degradation and loss in mechanical properties. In the current article, a comparative study of the effect of gamma-irradiation at different irradiation doses and the postirradiation oxidation on both the polymers is reported. The loss in mechanical properties was monitored by the bend angle and tensile measurements. The yellowness index measurements were carried out as a function of the irradiation dose and postirradiation storage time. The changes in the molecular weight (MW) and molecular weight distribution (MWD) were monitored using melt index (MI) measurements. The changes in chemical structure was determined using infrared spectroscopy. (C) 1997 John Wiley & Sons, Inc.