Fire retardant rigid polyurethane foam: Use of phosphorus-nitrogen additives

Rigid polyurethane foam (RPUF) is widely used in many industrial applications, including insulation panels for buildings, packaging, transportation, automotive and cold chain storage. By its chemical nature, RPUF is easily ignitable and highly flammable. On burning it produces large quantity of vision obscuring smoke with highly toxic gases such as hydrogen cyanide and carbon monoxide. Thus, flammability of RPUF is an important industrial issue. The influence of phosphorusnitrogen additives based composition on physical properties and fire behavior of RPUF was investigated. RPUF samples were impregnated with various concentrations of P-N based additives composition at ambient conditions. Optimum impregnation time, retention and density of RPUF samples with P-N composition were studied. The morphology and elemental analysis of RPUF and RPUF-P-N samples were studied with scanning electron microscopy (SEM), CHNS analyzer and energy dispersive x-rays (EDX). The deposition of PN on the cell walls and surfaces was exhibited by decreased cell size from 357 to 285 m. CHNS and EDX studies showed the introduction of phosphorus and nitrogen into the RPUF matrix. Fire behavior of RPUF and RPUF-P-N samples were investigated with BS: 4735. It was observed that RPUF-P-N samples showed reduced extent burnt, burning rate and percent mass loss.