Modified unsaturated polyester resins synthesized from poly(ethylene terephthalate) waste, 1. Synthesis and curing characteristics

Abstract

The depolymerization of poly(ethylene terephthalate) (PET) by alcoholysis reaction is an easy operation and gives prospects for the valorization of wastes. PET waste was first depolymerized by glycolysis reaction at different molar ratios of diethylene glycol (DEG), in the presence of Mn acetate as a transesterification catalyst. The glycolyzed products obtained were reacted with p-hydroxybenzoic acid (PHBA) and maleic anhydride (MA) to prepare modified unsaturated polyesters. The molar ratio of added PHBA was varied in order to investigate its effect on the curing characteristics of these modified unsaturated polyesters. The data obtained revealed that an increasing molar ratio of PHBA, within the studied range of concentrations, leads to a reduction in the peak exothermic temperature (Tmax) accompanied with the required delay in the curing time. The curing characteristics of these modified polyesters are not so fast anymore, which is not manageable and considered as disadvantageous from the practical point of view, showing instead a moderate speed.