THE EFFECTS OF $gamma$-IRRADIATION ON CARBON TETRACHLORIDE SOLUTIONS OF POLYISOBUTYLENE AND POLYSTYRENE

Carbon tetrachloride, because of its large G-value, was used as the solvent in studying whether the effects produced in polymers were direct or indirect. Since the solution concentrntion is impontant for this purpose, polyisobutylene solutions of 0.2, 0.4, 0.8, and 1.6% were irradiated with a 300-c Co/sub 60/ source in the absence of air at a dosage rate of 0.05 Mr/hr at 30 plus or minus 2 deg C up to 0.98-4.39 Mr. Similarly, polystyrene solutions of 0.4, 0.8, and 1.2% were irradiated with a 3000-c Co/sup 60/ source at the rate of 0.38 Mr/hr up to 2.2 to 6.7 Mr. A considerable decrease in molecular weights was observed in all cases. For polyisobutylene, degradation became more rapid in dilute solutions than in the solid stat and increased with increasing dilution. Hence, it was concluded that its main chain scissions were due to the indirec action by the free radicals formed in the solvent. On the other hand, the degradation of polystyrene solutions was not affected by concentrations, and it was concluded that this was the result of the direct radiation effect. (OID)