A Cone Calorimetric Study of Flame Retardant Elastomeric Polyurethanes Modified with Siloxanes and Commercial Flame Retardant Additives

Polyurethanes are the single most versatile family of polymers with a wide range of applications. There is a substantial need for the development of polyurethane materials with low heat release rate and low smoke release rate. In this study, an extensive series of elastomeric polyurethanes based on diphenylmethane-4,4'-diisocyanate (MDI) prepolymers were prepared and fur ther modified with fluid and powered siloxanes and conventional flame retardant additives. The flame retardant behavior of these polymers was studied using the Cone Calorimeter (ASTM E-1354), the instrument that has emerged as an impor tant tool for the analytical testing of materials for their fire properties. ** All pow dered siloxane additives used in this study, even at 5% loading level, gave a 70-80% reduction in peak heat release rates compared to standard materials.The reductions of peak HRR of fluid siloxane-modified materials compared to the base material were in the range of 49-78%. The conventional flame retardant addi tives used in this study also reduced peak heat release rate dramatically. The syn ergistic effect of conventional flame retardant additives with siloxane powders is discussed.