Effects of Gamma Irradiation on Polyethylene, Polypropylene and Polystyrene Containing Antioxidants

The polyethylene (PE), polypropylene (PP) and polystyrene (PS) films and sheets were made with antioxidants, and the contents of additives, volatiles and other chemicals, tensile strength, color and odor were tested after gamma irradiation of 0, 10, 30 and 50 kGy dose. The antioxidants decreased uponradiation, BHT and Irgafos 168 disappeared more rapidly than Irganox 1076 and 1010. The degradation products of polymer, such as acetic acid, propionic acid, 2-methyl-2-propanol and 2, 2-dimethylpropanoic acid, were produced more in PP than PE, and the presence of antioxidants reduced their formation.On the other hand, 2, 4-di-tert-butylphenol and 2, 6-di-tert-butyl-1, 4-benzoquinone were found as degradation products of antioxidants. PP films became fragile upon irradiation and even a high level of BHT could not protect, while the combination of three antioxidants was more effective. Coloration was more pronounced, and odors were stronger in the films containing BHT. In PS sheets, the antioxidants decreased only slowly and the degradation product was formed only in small amounts.