Gel Formation of Aqueous Solution of Polyvinyl Alcohol Irradiated by Gamma Rays from Cobalt-60

Experiments were carried out on the irradiation of aqueous solution of polyvinyl alcohol by gamma rays. For sufficient dose of radiation, the polymer molecules in the solution interlinked with each other and formed an insoluble gel. The change in degree of polymerization of the polymer with the absorbed dose, and the minimum dose R g , required to produce a gel, were measured as a function of concentration of polyvinyl alcohol. In dilute solutions below the critical concentration, gel formation did not occur even for prolonged irradiation. Some considerations are given on the phenomena.