Effects of gamma irradiation on PVC/PS blends

Commercial polystyrene (PS) has been studied as a modifier for commercial poly(vinyl chloride) (PVC) when submitted to gamma irradiation. PVC is a polymer widely used for the food packaging and/or medical supplies which receives gamma rays on sterilization process. PVC/PS films were prepared with 100/0, 95/05 and 90/10 compositions by casting solution method. Results about gamma-irradiated (60Co) PVC/PS films at irradiation doses of 15, 25, 50 and 100 kGy (in presence of air and at room temperature) are reported. The changes in viscosity-average molar mass (Mv) were analyzed by viscosity technique using an Ostwald-type capillary viscometer. PVC films showed both crosslinking (at 15 kGy dose) and main chain scissions (at 25-100 kGy dose range) phenomena. On the other hand, PVC/PS blend film in the 95/05 and 90/10 composition showed only main chain scission effect with increasing of dose radiation. Our study showed that the addition of PS into PVC matrix decreased 78% (95/05) and 70% (90/10) the number of scissions/100eV at dose range of 25-100 kGy. The analyses of FT-IR spectra in C-Cl vibration showed negligible intermolecular interactions between the components of PVC/PS blends and the miscibility of polymer pairs is limited for compositions in study. (author)