Preparation of Urethane Oils from Microwave-Assisted Glycolyzed Products of Waste PET Bottles

Post-consumer PET bottles were depolymerized with propylene glycol at a weight ratio between PET and glycol of 37.5 : 62.5 under microwave energy at irradiation power of 600 watt, using zinc acetate as a catalyst. The glycolyzed product, consisting of oligomeric diols with a hydroxyl value of 253 mg KOH/g, was obtained. Analysis of the glycolyzed product by GPC indicated that it consists of compounds with a number-average molecular weight of 2265. The glycolyzed product was further reacted with linseed oil and toluene diisocyanate to obtain urethane oil at hydroxyl to isocyanate ratio of 1 : 0.8 with methanol acting as a blocking agent. It was found that the obtained urethane oil was a transparent yellowish liquid with low viscosity. The prepared urethane oil was characterized for molecular weight and its properties were determined and compared with those of the conventional and commercial urethane oils. Results showed that the properties of waste PET bottles-based urethane oil were comparable to those of the commercial urethane oil.