Effect of pressure on the radiation-induced cross-linking of some vinyl polymers

The effects of compression on the solid state, radiation-induced cross-linking of polyvinyl chloride, polystyrene and polyacrylamide were studied. The cross-linking yield increased and the dose for incipient gelation, rsub(g) decreased with the pressure applied on the polymers before irradiation. The cross-linking yield, however, decreased with further increase in the pressure indicating the existence of optimum pressure for cross-linking. These phenomena were observed for all of the three polymers, but they differed with the type of polymers, molecular weights and radiation intensity. In the case of polyvinyl chloride, dehydrochlorination also occurred but the effect of compression on the dehydrochlorination was small. (author)