Study of cure kinetics of DGEBA with optically active curing agents

Abstract

3-Deoxy-D-erythro-hexos-2-ulose bis (thiosemicarbazone) (I) readily obtained from d-glucose reacts with copper acetate hydrate to give the corresponding chelate (II). The complex (II) was acetylated to give the corresponding tri-O-acetyl derivative (III). The (I), (II), and (III) were used as optically active curing agents for diglycidyl ether of bisphenol A (DGEBA)-based epoxy resin, and the cure reaction was studied by the non-isothermal DSC method. The maximum exothermic temperature (Tp) of curing of DGEBA-(III) system shifted about 313 K toward lower temperature in comparison with the Tp of DGEBA/(II) system. The average Ea values obtained by using Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and isoconversional methods for non-isothermal curing of DGEBA-(I), DGEBA-(II), and DGEBA-(III) systems are 95.8, 135.5, and 85.8 kJ mol−1, respectively. The higher reactivity of (III) toward epoxide groups can be due to better solubility of the (III) in DGEBA as a result of acetylation of hydroxyl groups.