Synthesis and curing of rod-like epoxies with alkoxy groups as flexible side chain

Summary

A series of aromatic diepoxides consisting of rigid ester unit with different lengths of flexible alkoxy side groups (R = H, OCH₃, OC₃H₇, and OC₈H₁₇) were synthesized, and their thermal and cure behavior with aromatic diamine were investigated by using a DSC. The values of melting temperatures for the epoxy monomers ranged from 65 to 221°C depending upon the length of side groups. Cure kinetics of an epoxy/4,4′-diaminodiphenylmethane (DDM) system with two different side groups (R = OC₃H₇ and OC₈H₁₇) forming homogeneous mixture was examined using a multi-temperature scan method, developed by Ozawa and Kissinger, in order to determine the activation energy (E) and the frequency factor (A). The epoxy monomer having longer side group showed smaller E and larger A, indicating that the introduction of the long flexible side group could accelerate the cure reaction of rod-like epoxy.