Gamma and electron beam radiation induced physico-chemical modifications of poly(propylene)

The homopolymer PP, a plastic material used as packaging and for medical pr oducts, must be subjected to a form of sterilization. Nowadays, one kind of this technology uses ionising radiation, which can be gamma-rays or electr on beams. In order to study the structural modifications of polymer syringe s which could occur following these treatments at different doses (25-150 k Gy), several analytical techniques have been used. DSC provided information on changes in the cristallinity of the polymer. The thermal evaluation was supplemented by testing the rheological properties of polypropylene. In ad dition, Reversed Phase Liquid Chromatography (HPLC) with a quaternary eluti on gradient was carried out for the evaluation of the degradation of the ad ditives. Thermogravimetric analysis (TGA) coupled with Fourier transform in frared (TGA/FTIR) was used to measure the desorption of food simulating liq uid (CH2Cl2). First, the results obtained proved that the gamma-rays as wel l as the electron beam induced degradation of the polymer and its additives . Next, we compared the effects of gamma and electron beam irradiation to d etermine which of these two processes better maintained the integrity of th e irradiated product. (C) 1999 Published by Elsevier Science B.V. All right s reserved.