Poly(
ethylene terephthalate), PET is one of the versatile engineering plastics, which is used extensively to manufacture
fibers, photographic films, and bottles for packaging. The overall world consumption of PET amounts to about 13 million tons, of which 9.5 million tons are processed by the textile industries, 2 million tons are consumed in the manufacturing of audio and video tapes, and 1.5 million tons are used in the manufacturing of various types of packaging mainly bottles and jars. PET
does not create any direct hazard to the environment, but due to its substantial volumes in the plastics waste stream and its high resistance to the atmospheric and biological agents, may be thought of as a noxious material. Therefore, the recycling of PET will not only serve as a partial solution to the solid waste problem but also contributes to the conservation of raw petrochemical
products, the preservation of resources and the protection of the environment. PET wastes can be melted and then remanufactured. However, the products possess inferior properties and are limited in application. In contrast, chemical recycling can be realized by depolymerizing PET wastes into their original monomers from which virgin resins with excellent performances are resynthesized. This paper attempts to investigate and identify the glycolyzed products, when PET recycled from postconsumer soft-drink bottles, is depolymerized by Glycolysis in excess of ethylene glycol, EG at the boiling point of ethylene glycol, 196°C under nitrogen atmosphere up to 10 hours, in the presence of zinc acetate as transesterification catalyst. The Glycolysis reaction is as an effective way for its recycling and carried out with a weight ratio of ethylene glycol, EG to PET from 0.5 to 6; and weight ratio of catalyst to PET from 0 to 1.5%. The optimal conditions are reaction time of 3 h, weight ratio (EG to PET) of 5, and weight ratio (catalyst to PET) of 1%. The glycolyzed products consist mostly a mixture of the PET monomer, ethylene glycol, EG, diethylene glycol, DEG, bis(2-hydroxyethyl
terephthalate), BHET, monohydroxyethyl terephthalate, MHET, the dimer and poly(ethylene terephthalate) oligomers, EG–(TPA–EG)n for
n = 1–3. The glycolyzed products were analyzed for hydroxyl value, HV and acid value, AV, separated into monomer and oligomers and identified by different techniques, such as IR, element analysis, differential scanning calorimeter, DSC, 1H NMR, 13C NMR, and gel permeation chromatography, GPC. It was found that the Glycolysis products consist mainly of bis (2-hydroxyethyl) terephthalate), BHET and monohydroxyethyl terephthalate, MHET which was effectively separated from dimer in white crystalline form. X-ray diffractions were confirmed the structures of BHET and MHET.