TIME-RESOLVED STUDY OF THE HIGH-ENERGY RADIATION INITIATED POLYMERIZATION

The EB (electron beam) initiated polymerization of ethyl acrylate (EA) and ethyl methacrylate (EMA) in dilute cyclohexane solution was studi ed by pulse radiolysis technique with transient spectroscopic detectio n. The maximum in the absorption spectrum of the intermediates lies at lambda = 290-320 nm in EA solution and at lambda = 285 in EMA solutio n. The extinction coefficients of the intermediates at the maximum of the spectrum were calculated to be epsilon(285nm) similar to 700 mol(- 1) dm(3) cm(-1) in EMA solution and epsilon(290-320nm) similar to 300 mol(-1) dm(3) cm(-1) in EA solution. From the decay curves rate parame ters of termination (2k(t)) were calculated. The decays were generally found to be second order with a rate coefficient of 1.4 x 10(9) mol(- 1) dm(3) s(-1) in EMA solutions and 6 X 10(8) mol(-1) dm(3) s(-1) in E A solutions. In some cases deviation from a single second order was ob served. This was interpreted in terms of the hindered mobility of the growing radicals.