Radiolysis of polymethylmethacrylate in the presence of ethylmercaptan. I. Main chain scission and volatile products formation

Abstract Main chain scission yields Gs are, respectively, 0.88 and 2.6 for polymethylmethacrylate (PMM) irradiated at 77 and 313°K. G values for volatile products (mainly CH4, CO, CO2, HCOOCH3) were measured. The ratio of methyl containing volatiles to main chain scission yield is about one at both temperatures. In the presence of ethylmercaptan, very efficient protection is observed for main chain scission whereas the amount of volatile products is little or not affected. These results show that side chain scission and main chain breaking are closely related and that the former process precedes and induces the latter. A mechanism is proposed.