Synthesis of unsaturated polyester from glycolyzed PET waste and characterization

Abstract

Waste polyethylene terephthalate (PET) is glycolyzed along with virgin PET. A higher proportion of virgin PET in the mixture has the ability to consume more glycols during glycolysis. This gives rise to a glycolyzed PET (GPET1), which contains a lesser amount of free glycol and shows the highest hydroxyl value. During polyesterification of the polyester diol (glycolyzed PET) with maleic acid, the degree of polymerization (DPn), extent of reaction and acid value is observed to be increasing with an increase in the virgin PET content in the mixture. This is believed to be due to the increasing presence of BHET (bis hydroxy ethylene terephthalate) in the glycolyzed PET.