Thermal Characteristics of Different Plastics
Thermal decomposition of different plastic through pyrolysis can be achieved at different temperature range. Through TGA analysis of various plastics, including PP, PS, LDPE and HDPE, carried by Lee and Shin , it was found that PS has the lowest degradation temperature compared to PP and PE thus will decompose more easily into liquid products. Degradation of PS occurs almost in the range of 350 to 460̊C, similarly to Jude et al.  where complete degradation occurred at 400̊C, while PP degradation occurs between 380 to 490̊C. Moreover, LDPE and HDPE decompose in temperature range of 400 to 500 and 550̊C. This is also been determined by Lopez et al  in terms of rate of mass loss of PE, PP, PS, PET and PVC. The results showed almost similar temperature range as in  for PE, PP and PS. Moreover, maximum degradation showed to occur at 490, 470 and 420̊C for PE, PP and PS. Therefore, it can be determined that temperature in the range of 450 and 500̊C will be suitable for pyrolysis of plastic.
Effect of plastic composition on the pyrolytic oil yield and composition
The role of plastic waste composition on the yield of the pyrolysis end-products was studied in which seven different plastic mixtures were pyrolysed using autoclave at 430̊C with heating rate of 20̊C/min . Plastic mixtures were a combination of three main types of plastic; PE, PP and PS with different fraction resulting in 68PE, 68PP, 68PS, 100PE, 100PP, 100PS and 33 of individual type (numbers indicate the percentage fraction each type in the plastic mixture). Oil analysis showed that plastic sample with 100PS led to highest liquid yield (>90%) while the remaining samples show almost similar yield. PS corresponds to the aromatic content of the pyrolytic liquid with 100PS and 68PS of 96 and 77%v/v, respectively. However, with increased fraction of PE, alkane and alkene content of the liquid increased and became higher than aromatics. Increased amount of alkene and decreased content of alkane was observed when PP compromised the highest fraction of the mixture compared to PE. This indicates that the formation of alkane is favoured by the presence of PE in which more than 70%v/v was obtained with 100PE compared to 68%v/v with 100PP. In terms of aromatic composition of the PS pyrolysis derived oil, toluene, ethylbenzene and m-xylene formed the main components with highest concentration of toluene followed by ethylbenzene and m-xylene. Similarly, Miskolczi et al.  indicated that the formation of linear non-branched hydrocarbons and aromatics are coupled with the presence of PE and PS, respectively, in the plastic mixture. Since high RON increases the liquid applicability as an alternative to transport fuel, highest RON (~100) was obtained with 100PS reflecting high aromatic content of the liquid [5, 24]. According to Jude et al. , waxy product of LDPE thermal pyrolysis was found to contain mainly aliphatic compounds...