Microwave-Assisted Depolymerization Of Post-Consumer Pet Bottles For The Production Of Rigid Thermal Insulating Polyurethane Foams
Polyethylene terephthalate (PET) plastics are commonly used as water and soft drink bottles. Since these materials have poor biodegradability and high resistance to the atmosphere, it is not appropriate to dispose them by land-filling. Furthermore, these bottles contribute to the substantial plastic waste generation. Hence, this study aims to reduce the accumulation of waste PET bottles through chemical recycling, as well as find a waste alternative raw material for the production of rigid thermal insulating polyurethane (PU) foams. Post-consumer PET bottles were collected, dried and size-reduced. The PET flakes were subjected to microwave-assisted glycolysis in a modified microwave set-up with glycerine as depolymerizing agent to produce the glycolyzed product (GP). Glycolysis reaction time of 15 minutes yielded the highest percent conversion. The GP was then transesterified with castor oil to convert into polyester polyol. The derived polyester polyol was mixed with diisocyanate to produce rigid polyurethane. The GP, polyester polyol and PU foams were characterized using Fourier Transform Infrared spectroscopy (FTIR) to verify the presence of the expected functional groups. The final product was then analyzed by thermal gravimetric analysis (TGA) to determine its thermal stability as compared to that of commercial foam. The experimental foams were found to be more thermally stable compared to commercial polyurethane foams.
Keywordsó Post-Consumer Pet Bottles; Rigid Polyurethane Foams; Glycolysis; Microwave-Assisted Depolymerization; Transesterification; Oligoester; Polyester Polyol; Diisocyanate; Thermal Stability