Flammability of rigid polyurethane foams blown with pentane: Limiting oxygen index data and thermovision characteristics

In this paper we report the use of the limiting oxygen index (LOI) and thermovision camera methods to characterise the flammability behaviour of rigid polyurethane foams, based on diphenylmethane-4,4-diisocyanate, diphenyl-2,2-propane-4,4-dioxyoligo(ethylene oxide) and oxyalkylenated toluene-2,6-diamine, blown with pentane. It has been found that thermovision camera data may complement LOI results through a temperature distribution display, thus making it possible to describe a complex flammability behaviour of a polymeric material in a more comprehensive way. The influence of novel additives, namely sodium dihydrogenphosphate, trisodium pyrophosphate and sodium aluminocarbonate, on the flammability of rigid polyurethane foam is discussed in terms of (i) changes of the heat- and light-emitting zone of the flame and the distance from the pyrolysing polymer surface, and (ii) by restricting the diffusion of volatile decomposition products.