Flexible Polyurethane Foams under Fire Conditions

Experimental data are presented which illustrate the significant reduction in smoke and toxic gases generated during burning achieved by incorporation of fairly high concentrations of a smoke suppressant, maleic acid, in a standard polyurethane flexible foam. In addition to simple free burning of bare foam, two types of instrumented tests were used: (a) Small-scale (laboratory) tests involving exposure to radiant heat under controlled atmosphere in the QMC Conical Furnace; (b) Large-scale (fire room) tests of foam cushions fitted with viscose velour and polypropylene covers, and assembled into chair shapes. Modifications of the QMC Conical Furnace procedure have led to improved correlation between the results of the small-scale and large-scale tests, even when the latter are greatly influenced by cover-splitting during the burns. While chlorendic acid, ferrocene and potassium fluoborate exhibit some smoke-suppressant activity in bare foam, the only additive we tested which was effective in covered foams at the room scale was maleic acid. Chlorendic acid generated more smoke in covered foams than did the control. The efficacy of all additives varied with the burning temperature. Sorbitol, anisaldehyde, calcium stearate, trioctyl borate and two new ferrocene derivatives were ineffectual in our small-scale screening tests; maleic anhydride and furfural formulations could not be processed in the laboratory.