Effects of High Energy Radiation on Polymers III. Viscosity

Abstract

It was known that solubility of irradiated polymers was not free from the effect of cyclization. On the contrary, viscosity before gel point is not affected by it and it is utilized in order to investigate the effects of high energy radiation on polymers. Intrinsic viscosity is discussed first for the case where cross-linking and degradation occur. In certain cases intrinsic viscosity decreases in the initial period of irradiation, but increases in larger radiation doses, so that it has a minimum and becomes infinite at a certain radiation dose which corresponds to gel point. It is also derived that G -value of cross-linking and degradation are calculated from the intrinsic viscosity in the initial period of irradiation. An example of polyvinylchloride gives G -values whose orders of magnitude are not unreasonable. The more accurate is the measurement, the more correct values will be obtained. Intrinsic viscosity for the case where end-linking occurs is likewise discussed, and the same properties as those in cross-linking are derived. Finally we know that the gel point determined from an asymptotic behaviour of intrinsic viscosity will be more correct than that determined from an extrapolation of solubility curve.