Relaxation mechanism of epoxide resin cured with acid anhydrides. III. Effect of alkyl side chains on mechanical and dielectric β relaxations

Abstract

AbstractMechanical and dielectric β relaxations were investigated for bisphenol‐A‐type epoxide resin cured with succinic anhydrides with and without substituent linear or branched alkyl side chains. The dielectric β relaxation is due solely to the motion of the diester segment which is formed in the network from the reaction with the acid anhydride. The mechanical β relaxation is attributed to the motion of both the diester segment and another nonpolar segment, i.e., the linear alkyl side chain. Thus it is concluded that the long alkyl side chain in the diester segment not only restricts the motion of that segment, but also introduces additional motion of the side chain itself.