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

The depolymerization of poly(ethylene terephthalate) (PET) by alcoholysis r eaction is an easy operation and gives prospects for the valorization of wa stes. 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 react ed with p-hydroxybenzoic acid (PHBA) and maleic anhydride (MA) to prepare m odified unsaturated polyesters. The molar ratio of added PHBA was varied in order to investigate its effect on the curing characteristics of these mod ified unsaturated polyesters. The data obtained revealed that an increasing molar ration of PHBA, within the studied range of concentrations, leads to a reduction in the peak exothermic temperature (T-max) accompanied with th e required delay in the curing time. The curing characteristics of these mo dified polyesters are not so fast anymore, which is not manageable and cons idered as disadvantageous from the practical point of view, showing instead a moderate speed.