Polybutadiene modified by epoxidation: 2. The effect of epoxy groups on the crosslinking process with dicumyl peroxide

The process of crosslinking sodium and n-butyllithium polybutadienes as well as the products of their modification obtained by epoxidation has been studied. It has been found that the crosslinking efficiency of epoxy-1,2-polybutadiene is half that of the starting polybutadiene. However, the crosslinking efficiency of epoxy-1,4-polybutadiene was found to be similar to that of the starting 1,4-polybutadiene. The shift in glass transition temperature for epoxy-polybutadienes brought about by the change in the chemical composition (ΔTg)M was found to be 67 K for 1,4-polybutadiene, and 51 K for 1,2-polybutadiene. The effect of the epoxy groups and crosslinks on the glass transition temperatures of modified crosslinked polymers is also discussed.