Synthesis and curing of new aromatic azomethine epoxies with alkoxy side groups

Abstract

Four new aromatic epoxies containing azomethine unit as a backbone linkage and alkoxy group as a flexible side chain were synthesized and characterized by means of IR and NMR spectrometry, and differential scanning calorimetry (DSC). The carbon number ( n) of the alkoxy group was varied from hexyloxy (6) to nonyloxy (9). The cure kinetics for an epoxy/diamine-system was investigated by a DSC technique. From a multi-temperature scan method, developed by Ozawa and Kissinger, the activation energy ( E) and the frequency factor ( A) were determined and compared for the epoxies with different lengths of alkoxy group. The E and A value from Kissinger method are higher than those from Ozawa method for all side chain lengths. Each method shows that E increases slightly but A increases greatly when the length of the side chain increases. The large increase in A overriding the small increase in E may lead to the acceleration of the cure reaction as the side chain becomes longer.