Effects of Ammonium Polyphosphate/Melamine Additions on Mechanical, Thermal and Burning Properties of Rigid Polyurethane Foams

Rigid polyurethane foams are widely used as thermal insulation materials.However, the foams have fairly poor fire performance.Therefore, different flame retardants are used to enhance the fire resistance of the foams.Meanwhile, it should be pointed out that flame retardant additions into the foams may deteriorate the thermal and mechanical properties of the foams.In this study, intumescent flame retardants are synthesized by using ammonium polyphosphate/melamine in different ratios, namely 3/1, 2/1 and 1/1.The flame retardants were added into the rigid polyurethane foams in 10 wt%.The thermal conductivity, compressive strength, thermogravimetric analysis and UL 94 burning characteristics of the foams were determined and compared.As a result of the experiments, it was found that the best fire resistance can be satisfied with ammonium polyphosphate/melamine (3/1) addition.However, there were slightly increasing in thermal conductivity and decreasing in compressive strength of the foam.