Radiation resistance of polypropylene and its composites .1. Polypropylene

The gel permeation chromatography (GPC), MFR and ESR techniques were used to study the resistance to radiation, via molecular weight and viscosity determinations, in homopolymeric PP (Malen PJ 601 and PP 401), a propylene/ethylene copolymer (Malen PJ 330), and in PP modified with propylene/ethylene and ethylene/vinyl acetate copolymers (PP Mod MKE 93), each prepared at the IChiTJ, Warsaw. The MKE 93 and Malen PJ 330 were found to be most resistant to fast electrons. Irradiation resulted in the degradation and simultaneous reduction of polydispersity (cf. Tables 3, 4) in the PP examined. MFR measurements and GPC gave consistent results. The higher the polypropylene molecular weight, the greater the degree of degradation induced. The MKE 93, i.e., the PP most resistant to radiation, proved suitable for the production of radiation-sterilized hypodermic syringes.