Study on the Identification Method of the Combustion Residue of PVC Plastic Carpet in Arson Fire

In the fire investigation work with suspicion of arson, the combustibles in the fire scene often cause certain interference to the detection and identification results of the combustion improver. In this paper, PVC plastic carpet and typical combustion improver were selected and fire scene conditions were simulated to prepare combustion residues. In order to determine the appropriate physical evidence identification method, this paper conducted analysis and detection on the samples to be tested by using gas chromatography-mass spectrometry and thermogravimetric analysis techniques. Experimental results show that the gas chromatography-mass spectrometry technic can extract the characteristic components of gasoline combustion products from the mixed combustion residue of PVC plastic carpet and gasoline, such as normal paraffins, aromatic hydrocarbons, polycyclic aromatic hydrocarbons and indene compounds, which satisfies the detection and identification requirements of combustion improvers. Besides, the comparison of thermal weight loss rates between original PVC plastic carpet and the combustion residue of PVC plastic carpet and the mixed combustion residue of PVC plastic carpet and the combustion improver are as follows: original PVC plastic carpet > the mixed combustion residue of PVC plastic carpet and gasoline > the combustion residue of PVC plastic carpet. Based on the experimental results, both the above two methods can effectively detect out whether there is combustion improver adhered to PVC plastic carpet, which can distinguish the existence of combustion improver in the fire scene.