Influence of the gamma radiation on the Schulz-Blaschke constant value

When conventional polymeric systems are exposed to the radiation, they undergo several effects on their molecular structure as the cross-linking and main chain scissions. In this work, we used the viscometer method because of its simplicity and efficiency on evaluation of those effects. In general, changes on molecular structure may largely affect the physical properties of polymers. By data obtained from this method, we can calculate the intrinsic viscosity, [η], with direct application of Schulz-Blaschke equation: [η]=ηred/(1+ksb,ηesp) , and to obtain the average viscosity molar mass, Mv, through Mark-Houwink relation: [η]=K(Mv)a. An important parameter to calculate [η] is the Schulz-Blaschke constant, ksb, that depends on the polymer-solvent-temperature system. In this paper, it is studied the changes on ksb constant value of polymer system after exposition to the gamma irradiation. The polymers poly (methyl methacrylate), polystyrene and polycarbonate were chosen and irradiated in doses of 30 and 50 kGy. These polymers are often used on confection of medical supplies sterilized by ionizing irradiation. The results obtained before and after the exposition to the radiation showed large changes on ksb values of these materials. (author)