Radiation effects on poly (vinyl chloride)—I. gas evolution and physical properties of rigid PVC films

Radiation-induced oxidative degradation of PVC films using ⁶⁰CO-γ radiation has been investigated at room temperature. Quantitative analyses of evolved gases and oxidative product during irradiation under vacuum conditions and in the presence of oxygen were determined. The G-values of evolved from PVC films irradiated under vacuum were: G(HCl) = 2.3, G(H₂) = 0.18, G(CH₄) = 0.001, G(CO₂) = 0.007, and G(CO) = 0.01 while in the presence of oxygen at an initial pressure of 500 Torr, and the G-values were: G(HCl) = 3.0, G(H₂) = 0.2, G(CH₄) = 0.006, G(CO₂) = 0.09, G(CO) = 0.1, and G(O₂) = 1.5. The evolved gases and oxygen consumption were found to depend on oxygen pressure during irradiation of the PVC films. The intrinsic viscosity of rigid PVC was found to decrease at low doses and then gradually increase at higher ones. This may be due to the oxidative degradation occuring at low doses. On the other hand, crosslinking may be the predominant effect at higher doses. Mechanical properties of irradiated PVC films show that there is no significant change in the tensile strength until 0.6 MGy. Meanwhile, elongation percent increases with dose to reach a maximum at 0.1 MGy, and thereafter it sharply decreases at higher irradiation doses.