Synthesis and characteristics of biodegradable epoxy-polyester resins cured with glutaric anhydride

Biodegradable epoxy - polyester resins were synthesized in two steps: (1) the synthesis of the polyesters with allyl pendant groups, and (2) the epoxidation of the allyl groups in the polyesters. Polyesters with allyl pendant groups were synthesized by the melt copolymerization of succinic anhydride (SA) and allyl glycidyl ether (AGE) in the presence of benzyltrimethylammonium chloride (BTMAC) as the catalyst. The functionality of some polyesters was reduced by replacing a part of AGE with butyl glycidyl ether (BGE). The epoxidation of the polyesters obtained was carried out using m-chloroperbenzoic acid (MCPBA). The multifunctional epoxy - polyester resins were cured with different amounts of glutaric anhydride (GA). The course of the curing process was monitored using DSC method. The following parameters of the process were determined: heat of curing, onset, maximal and end temperatures. Glass transition temperatures (T_gs) of the cured resins were determined by dynamic mechanical thermal analysis (DMTA). The influence of the composition of the initial resins and amount of GA on the properties of the cured products, such as density, hardness, T_g values, swelling and water sorption, were examined. Epoxy - polyester resins were subjected to the test of accelerated hydrolytic degradation in an aqueous phosphate buffer of pH = 7.4 at 70 °C.