Smoke Evolution From Thermally Decomposing Polymers

In the interests of society, it is essential to take into account the potential hazards presented by new polymer materials prior to use especially by the general public. It has already been established that in a fire environment, smoke and combustion products from combustibles is the single largest cause of fatalities. Not Only ae... necessary to determine suitable testing procedures for polymeric materials, but analysis and modelling of these smokes as they affect persons in the immediate vicinity and also remote from the fire. The scientific principles of fifteen international standard test methods are researched in terms of the operating parameters, overall design and obtainable results. In simplistic terms, the aims of a smoke analysis procedure should be the determination of the many facets of the smoke producing potential of polymeric materials or assemblies. These facets include particulate size and growth mechanisms, smoke and polymer chemical composition, smoke temperature profiles, rate of smoke production, rate of polymer weight loss and distance/time from the fire base in terms of important environmental conditions; heat flux? air temperature, humidity and polymer composition. From this work a new smoke generating and testing apparatus has been developed and consequently it has been possible to establish graphical relationships between incident heat flux level, rate of smoke production, smoke particle size, and smoke temperature for Polystyrene, Polymethylmethacrylate, Polyvinylchloride and Acrylonitrile-Butadiene-Styrene. For Polystyrene this relationship has been extended to include the smoke chemical composition as a function of the decomposition mechanism. : An empirical linear equation has been developed which relates the rate of particulate growth within the smoke to the distance from the fire base. The results have been used to derive 'Ageing Coefficients' for each of the above polymers. These results have been measured by use of a laser diffraction particle sizer which permits in-situ analysis. The work has also highlighted many areas which need further research to advance the science of smoke studies.