The Burning Behaviour of Combustion Modified High Resilience Polyurethane Foams

Limiting (LOI) and extinction (EOI) oxygen index values have been determined for combustion modified high resilience polyurethane foams of a range of densities. The data obtained show that the value of the extinction oxygen index at zero ignition time, [EOI] _o , is less than the LOI value. [EOI] _o is directly related to the flame retardant concentration of the foam sample rather than foam density which is the determining factor of the LOI values. Thus the [EOI] _o parameter can be considered to be a superior measure of the intrinsic foam flammability. General conclusions are drawn as to the relationships be tween foam density and melamine flame retardant content and the LOI and [EOI] _o values.