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

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.