Development of lab-simulated slow pyrolysis and generation of pyrolysis profiles of common hydrocarbon polymers for fire debris analysis

Abstract

This study aimed to investigate the pyrolysis behaviour of substrates and the influence of various factors on the formation of degradation products through experimental and real world simulations. Experimental simulation involved the pyrolysis of substrates in an inert environment constructed of a glass ampoule and steel compartment. Real world simulation involved the pyrolysis of substrates under a thin metal sheet with external heat from a propane torch. Experimental simulation results illustrate the formation of aromatics from common polymers were possible when the temperature exceeded 550 ℃ for 30 min. The presence of a matrix profile can be masked by ignitable liquids when the ratio was greater than the substrate. Samples subjected to 550 ℃ pyrolysis produced strong positive correlation between all samples regardless of the substrate types or presence of ignitable liquid. Samples with similar chemical structure, such as PP, HDPE, LDPE had greater correlation between themselves compared to phenyl ring structured PER and PET. Nylon sample had closer correlation with aliphatic PP, HDPE, and LDPE. Aliphatic samples subjected to ≤300 ℃ pyrolysis had negative correlation with both aromatic (PC1) and oxygenated products (PC2). There was no secondary cracking for the cyclisation process to take place.