Ms. Farahat et al., Modified unsaturated polyester resins synthesized from poly(ethylene terephthalate) waste, 1 - Synthesis and curing characteristics, MACRO MAT E, 283(10), 2000, pp. 1-6
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.