Study On Identification Of Tyre Tread Rubber By Pyrolysis Gas Chromatography/Mass Spectrometry

In traffic accident and criminal cases, tyre tread rubber is one of the most often seen and very important material evidence. Analyze the chemical components of tyre tread rubber and discriminate different brands of tyre tread rubber are of great significance for delimiting and narrowing the scope of the suspect cars and deciding the vehicle. By pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) with less interference and high more precise, the study used this technique to do the qualitative identification and quantitative research of tyre tread rubber samples.Under different pyrolysis conditions, the pyrolysis products of NR, BR and SBR were analyzed by Py-GC/MS. The best pyrolysis temperature 590 ℃, time 15s and the characteristics pyrolysized products of three kinds of rubbers for analyzing tyre tread rubbers were determined. On this basis, collect 43 kinds of tread rubber samples to do qualitative and quantitative analysis. Qualitative analysis results show that according to the characteristic pyrolysized products, the main components of 43 tyre tread rubbers could be divided into four categories:named NR, SBR, NR/BR, NR/SBR. And 19 of 43 samples could be qualitatively identified. Quantitative analysis results show that according to the content of the characteristic pyrolysis products, which could be used to identify most of NR/BR and NR/SBR samples. And combined with the results of the qualitative identification, it could reach the purpose of distinguishing samples. The difference of the content of characteristic pyrolysized products between SBR samples was very samll, and the distinguish effect was not obvious. But SBR samples could be accurately identified with the content of the selected 27 kinds of pyrolysized products combining with pattern recognition method.In this thesis, by using Py-GC/MS technique to do the qualitative and quantitative analysis for tyre tread rubber samples, it can provide the theoretic reference and technical supports for identifying tyre tread rubbers in forensic science.