Thermal degradation of polyethylene mixed with poly(vinyl chloride) and poly(ethyleneterephthalate)

Thermal degradation of plastics such as polyethylene (PE), poly(vinylchloride) (PVC), poly(ethyleneterephthalate) (PET) and their mixtures (PE + PVC and PE + PET) was studied at 430 degrees C by batch operation to analyse the conversion of waste plastics into fuel oil. A visual inspection of the inside of the reactor was made and the macroscopic process of degradation was monitored. Products of degradation were classified into three groups: gases, liquids and residues in the reactor. The degradation of PE produced liquid products which consisted of C-5-C-25 fraction of hydrocarbons with a yield of 70 wt%. On the other hand, the degradation of PVC produced only 4.7 wt% liquid products which consisted of C-5-C-20 fraction of hydrocarbons and the degradation of PET produced no liquid products. The effect of mixing PVC and PET with PE on the yield and compositions of liquid products was investigated. The addition of either PVC or PET to PE decreased the overall liquid products yield; however, it promoted the degradation of PE into low molecular weight liquid hydrocarbon products. (C) 1996 Published by Elsevier Science Limited.