The properties of unsaturated polyester based on the glycolyzed poly(ethylene terephthalate) with various glycol compositions

Abstract

Unsaturated polyester (UP) based on the glycolyzed poly(ethylene terephthalate) (PET) with propylene glycol (PG), diethylene glycol (DEG) and their mixture was prepared and the influence of glycol compositions on the chemo-rheological behavior and the mechanical properties was studied. The glycolyzed products showed broad bimodal distribution in their molecular weights and the larger molecular weight oligomers were obtained with increasing DEG contents in DEG and PC mixtures. The gelation time of UP was delayed with increasing DEG contents. After 1 h curing, the final conversion level increased as the DEG contents increased. The tensile modulus decreased and the toughness of cured products increased with increasing DEG contents due to the flexibility of ether linkage in the DEG unit. (C) 1999 Elsevier Science Ltd. All rights reserved.