Radiolysis of polyisobutene. Part III. Effect of additives

Abstract

AbstractThe effect of various liquid additives on the degradation of polyisobutene exposed to 4 M.e.v. electrons has been studied by solution viscometry and by measurement of gas volatile at −196°C. At a concentration of about 10−4 mole/g. some additives result in an increased yield of fractures, the maximum observed being about 20% with nitrobenzene, presumably due to the scavenging of polymer radicals which otherwise would combine. At higher concentrations most additives result in a decrease in the yield of fractures. Thus, 2 × 10−3 mole/g. thiophenol decreases the yield by about two‐thirds and itself suffers sensitized decomposition as evidenced by an increase in the yield of gas from the irradiated mixture. In the simplest case, di‐n‐butyl disulfide has a symmetrical effect in suppressing part of the yield of fractures and gas. This is consistent with the view that a proportion of the fractures is associated with gas formation.