Polyurethane foams with functionalized graphene towards high fire-resistance, low smoke release, superior thermal insulation

Abstract

To overcome the contradiction among flame retardancy, smoke suppression and thermal insulation for polyurethane foams (PUFs), in this manuscript, a novel functionalized graphene (FGN) is designed and prepared from expandable graphite (EG) and phosphorus-containing compounds. This FGN decorated with phosphorus-containing epoxy shows excellent compatibility with polyurethane matrix, leading to an improved compressive strength and decreased thermal conductivity as low as 0.02975 W/(m∙K). Notably, the resultant PUFs with FGNs exhibit great fire resistance and smoke suppression performance. With only 50 pphp FGNs (6.1 wt%) incorporated, the composite foam can pass the UL-94V-0 rating with a high limiting oxygen index value of 27. More importantly, the incorparation of FGNs not only effectively reduces the heat release rate (HRR) and total release rate (THR) of PUFs, but also significantly suppresses smoke release of materials during combustion. The mean specific extinction area (mSEA) and total smoke production (TSP) values of the composite foam can be reduced to 208.52 m2/s (−70.0%) and 2.08 m2/m2 (−66.0%), respectively. These characteristics with high fire resistance, excellent smoke suppression and low thermal conductivity very beneficial for polyurethane foams used as thermal isolation materials.