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 landfilling.
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 sizereduced.
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.
Keywords— Post-Consumer Pet Bottles; Rigid Polyurethane Foams; Glycolysis; Microwave-Assisted Depolymerization;
Transesterification; Oligoester; Polyester Polyol; Diisocyanate; Thermal Stability