Chemical conversion of PET waste using ethanolamine to bis(2-hydroxyethyl) terephthalamide (BHETA) through aminolysis and a novel plasticizer for PVC

Abstract

Poly(ethylene terephthalate) (PET) recycling has been carried out by various methods, e.g., mechanical recycling, chemical recycling and energy recovery method. In this study, chemical recycling of PET was carried out by aminolysis using ethanolamine and converted into bis(2-hydroxyethyl) terephthalamide (BHETA). The reaction was performed by varying the PET:ethanolamine ratio, reaction time and catalyst used for waste medical grade bottles of PET. Yield of about 81 % was obtained for PET:ethanolamine ratio of 1:4 (w/w), with 3 h reaction time, at 160 °C with zinc acetate as a catalyst. BHETA was characterized with FTIR, 1H NMR, and DSC analysis. BHETA was further reacted with heptanoic acid at a molar ratio of 1:2.5. The product obtained was used as a plasticizer for PVC at 5, 10, 15 and 20 parts per hundred (phr) concentration. Thermal and mechanical tests were carried out and the result obtained was compared with the virgin PVC without plasticizer and with conventional plasticizer of PVC, i.e., dioctyl phthalate at 15 phr concentration since new plasticizer showed excellent properties at 15 phr concentration. This newly synthesized plasticizer was completely fused with PVC and in tensile testing helped in increasing the elongation, which was an indication of the plasticization effect shown by this developed material. Glass transition temperature also decreased with an incorporation of the new plasticizer as compared to virgin PVC.