Dependence of the Crosslinking Efficiency on the Reaction Conditions in the Peroxide Crosslinking of Unsaturated Polyolefins

The crosslinking reactions of several unsaturated polyolefins with organic peroxides were carried out in an attempt to establish the dependence of the crosslinking efficiency on the reaction conditions, especially the reaction temperature and the peroxide concentration. Usually, the efficiency gradually increased up to a certain temperature and then decreased abruptly. This efficiency decrease can be considered to be due to (1) a decrease in the hydrogen abstraction, which is one reaction producing crosslinks, and (2) an increase in the termination rate in a chain reaction arising from opening up the double bond, which is another reaction producing crosslinks. Except for cases in which an extremely high temperature was employed or when a very high concentration of peroxide was used, the efficiency decrease by scission reaction upon an elevation of the temperature seems to be comparatively small.