Synthesis and Characterization of Non-Isocyanate Polyurethanes using Diglycidyl Ether of Bisphenol Acetone (DGEBPA) Epoxy Resin

Present work focuses on synthesis of non-isocyanate polyurethane (NIPU) using the conventional epoxy resin, diglycidyl ether of bisphenol acetone (DGEBPA). The conventional polyurethanes (PUs) are prepared by reaction of the toxic diisocyanates and polyols. The epoxy resin contains two epoxy groups which are converted to cyclic carbonate groups when reacted with carbon dioxide. In this work, the epoxy resin (ER) was converted into the cyclocarbonated epoxy resin (CCER) using methyltriphenylphosphonium iodide (MePh.I) as the catalyst and ethyl cellsuolve as the reaction medium. The reaction was carried out in a carbon dioxide atmosphere, slightly above the atmospheric pressure, for 20 h. The progress of reaction was monitored by percent oxirane oxygen content (%OOC). The FTIR study confirms the disappearance of epoxy groups at 910 cm-1 and appearance of cyclic carbonate groups at 1800 cm-1. The films of the resulting resin were prepared by curing with diethylamine (DEA), ethylene diamine (EDA) and reactive polyamide resin (70% NV). The formation of urethane linkage was confirmed by FTIR spectrum. The mechanical, chemical and appearance properties of the resulting NIPU were studied. The results were satisfactory, like improvement in adhesion and alkali resistance, but reduction in gloss and colour retention was observed. This eco-friendly route for synthesis of polyurethane can be used easily and variation in properties can be obtained by selecting the suitable epoxy compound as well as curing agent.