Chain extension of partially neutralized carboxyl-terminated liquid polybutadiene with bisepoxide

Chain extension of partially neutralized carboxyl-terminated liquid polybutadiene (PB) with bisepoxide was investigated by the carboxyl–epoxide reaction. The partially neutralized liquid PB were prepared, by the partial neutralization with MgO and CaO, from a carboxyl-terminated liquid PB (Hycar CTB 2000X162). As the bisepoxide, hydroquinone diglycidyl ether was used. The metal carboxylate groups in the system catalyzed the reaction and, further, the Mg carboxylate group showed higher catalytic activity than the Ca carboxylate group. The chain-extended metal-containing PB obtained by the reaction were found to be elastic when subjected to a rapid impact, but plastic under slowly applied stress and their solution behavior in pyridine was examined. The viscosities were very low at very low concentrations but increased markedly as the concentration increased. This solution behavior is attributed to ionic associations of carboxylate anions and metal cations to longer chains. Further, thermal and other properties were evaluated.