Recycling of PET wastes using Electron beam radiations and preparation of polyurethane coatings using recycled material

Poly (ethylene terephthalate) (PET) products consumption has been increased dramatically over the past few decades which have resulted in generation of large quantity of PET waste. Disposal of this waste is a global concern due to its nonbiodegradability. In the present study, we report the effect of electron beam (EB) radiations on degradation of PET and its subsequent effect on glycolysis by using excess ethylene glycol (EG). The results as analyzed by molecular weight determination showed an increase in the extent of depolymerization of PET proportional to the dose of EB irradiation. The irradiated PET samples were further subjected to chemical recycling by glycolysis using conventional and microwave method in presence of excess EG and zinc acetate (0.5%) as a catalyst. Depolymerization of PET by EB irradiation resulted in increased yield of BHET after variable time intervals. The recycled material BHET was subjected to esterification using linseed oil fatty acid, further epoxidation using formic acid and hydrogen peroxide and subsequent hydrolysis to prepare ecofriendly polyol. The individual step product was analyzed for its physical and chemical parameters like% NVM, hydroxyl value, acid value, iodine value, oxirane oxygen content etc. and also characterized by spectroscopic analysis like FTIR, H-1 NMR, C-13 NMR and GPC technique for molecular weight determination. Polyurethane coatings based on this polyol were prepared using various commercial polyisocyanate curing agents. The coated films were evaluated for their optical, mechanical and chemical properties. Thermal properties of coatings were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). (C) 2017 Published by Elsevier B.V.