Identification of volatile organic compounds in the early stages of fire from commercial products

Abstract

Building products, such as insulation materials, are ubiquitous in daily life, but there is a lack of published research on their thermal behaviour and volatiles released in the early stages of a fire. In both analytical and applied applications, knowledge about the chemical processes taking place during pyrolysis is essential. Many techniques have been used to study the thermal degradation of polymers with some having general applicability for polymer characterisation, whilst others including thermal volatilisation analysis, pyrolysis mass spectroscopy and analysis by infrared spectroscopy are used to look at the formation of specific molecules or groups in degrading products as well as changes in their concentrations.
A number of different insulation materials (expanded polystyrene, phenolic foams, polyisocyanurate foams, polyurethane foams and wool-based insulation materials) were analysed via X-Ray Fluorescence, Energy Dispersive X-Ray analysis and a CHNS elemental analyser to provide a brief overview of their elemental composition and allow likely decomposition products to be predicted. The materials were then thermally degraded in both air and inert environments via thermogravimetric analysis, differential scanning calorimetry, micro-scale combustion calorimetry and pyrolysis to identify the decomposition temperatures and points of significant heat and volatile release. The released volatiles were then analysed via Gas Chromatography-Mass Spectrometry and gas phase Fourier Transform Infrared Spectroscopy. The data was analysed in terms of toxicity.
The study found that some common insulation materials released volatiles which have been linked to various health problems. Acute asphyxiants such as hydrogen cyanide, carbon monoxide and carbon dioxide were identified from the FTIR analysis of decomposition in air, while carcinogenic and potentially carcinogenic volatiles, such as benzene and various polycyclic aromatic hydrocarbons, were identified amongst the released volatiles from the GCMS analysis.