Radiation crosslinking and scission parameters for poly(vinyl methyl ether) in aqueous solution

In oxygen-free aqueous solutions, poly(vinyl methyl ether) (PVME) was subjected to gamma irradiation. In such conditions PVME radicals recombine by way of crosslinking. The major result of crosslinking is an increase in the average molecular weight of the polymer, which close to the gelation point tends to infinity. Further irradiation increases the amount of formed gel, while the soluble fraction - sol decreases. The basic parameters related to the radiation processing are gelation dose - D-g, as well as radiation yield of intermolecular crosslinking and scission, G(X) and G(S), respectively. There are three general approaches for estimation of those parameters. The first method is based on the study of molecular weight changes before the gelation point. The second method combines the gel-sol as well as the swelling analysis results. The third one allows one to calculate the yield of crosslinking from the value of D-g. All of these methods of calculation were used in this work for determination of radiation parameters and results obtained are discussed. (C) 2003 Elsevier B.V. All rights reserved.