Investigation the effects of nanoclay and intumescent flame retardant additions on thermal and fire behaviour of rigid polyurethane foams

Abstract

Different inorganic materials are added into rigid polyurethane foams for improving properties and reducing production costs. Among them, it was found that nanoclay was added up to 6 % in the total mass. In this study, with the best knowledge of the authors, nanoclay / intumescent flame retardant composed of ammonium polyphosphate and pentaerythritol were added up to 15 % in the total mass into the rigid polyurethane foams for the first time. The effects of nanoclay and intumescent flame retardant additions on the cell size, the coefficient of thermal conductivity, the thermal degradation and the fire resistance were investigated. Furthermore, there is a lack of information in the literature about changes of the thermal conductivity of the foams with respect to time and the effects of fillers and flame retardants on the changes. Therefore, the changes of thermal conductivity coefficients of the foams were examined during two months after the productions. Experimental results indicated that the fire resistance and the thermal stability of the foams could be enhanced with 15 % nanoclay addition. However, nanoclay and the intumescent flame retardant additions into rigid polyurethane foams caused better thermal stability and fire resistance. Meanwhile, it was found that the incorporation of nanoclay / the intumescent flame retardant resulted in slightly increasing in thermal conductivity of the foams.