Synergistic effect of melamine and tricresyl phosphate on fire retardant properties of semi flexible polyurethane foam

Semi flexible polyurethane (PU) foam provides various applications in aerospace as well as daily life due to its vibration dampening, sound absorption, thermal insulation properties etc. One of the major disadvantages of PU foams is its poor fire-resistant characteristics. The present study aimed to improve the fire retardant behavior of PU foam by incorporation of fillers like melamine powder (M.P) and tricresyl phosphate (TCP) in PU matrix. A set of PU foams were prepared with M.P alone, with TCP alone and with a combination of both melamine powder and TCP. The effect of these fire retardants on mechanical, thermal and fire retardant properties of semi flexible PU foam were evaluated based on density, resilience ball rebound, compressive strength, tensile strength, thermal stability, thermal conductivity, limiting oxygen index (LOI) and fire test. In addition, Cell morphology of PU foam was examined using scanning electron Microscope (SEM). LOI was improved from 19% to 26% with the addition of fire retardants. Cushioning property was retained however density was increased with the addition of fire retardants. 40% melamine powder and 40% TCP with respect to premix have been chosen as the optimized composition based on the fire resistant and physical properties. Scale up studies of the developed PU foam was done up to 1 m × 1 m size foam pad. With respect to the lab level properties, LOI value of 26% was retained and resilience ball rebound value change was found to be minimal.