Research Of Polyurethane Microcellular Elastomer Halogen-Free Flame Retardant Properties

Microcellular polyurethane elastomer (MPUE) was widely used in many fields because of excellent properties such as high strength and wear resisting. The MPUE has poor flame retardancy and environment problems was been increasing seriously, so how to develop excellent flame retardant properties of MPUE is the main work of this paper.There are three kinds of additive type flame retardant ammonium polyphosphate (APP), the expandable graphite (EG) and RN-36(Phosphorus liquid flame retardant). Each one of them can improve the flame retardancy of MPUE, but will damage the mechanical properties. In the same content, the oxygen index of the EG flame system is higher than RN-36/MMPUE and APP/MPUE system. The addition of EG can greatly reduce the material combustion heat release rate and smoke production rate. When the combustion to 200s, the peak heat release rate was 88.6kW/m2 and smoke production rate was 129.7m2/s.Ammonium polyphosphate/expandable graphite complex system and Magnesium hydroxide/expandable graphite complex system has good flame retardant synergy.In APP/EG complex system, APP can enhance the MPUE combustion of carbon residue content. In the APP:EG=1:1, The oxygen index of MPUE system can reach 32 and UL-94 achieve the V-0 level. In the Mg(OH)2:EG=1:3, The oxygen index of MPUE system can reach 29 and UL-94 achieve the V-0 level, The initial thermal decomposition temperature of MPUE can improve 30℃. There are also have good flame retardant synergy between Mg(OH)2 and EG.Phosphate reactive flame retardant polyols PF-2011 can obviously improve the flame retardant properties and the mechanical properties of MPUE. When the content of PF-2011 was 50%, the tensile strength of MPUE was increased from 4.7MPa to 9.6MPa. This kind of flame retardant polyols can’t improve the thermal stability of MPUE.PF-2011 and expandable graphite complex system has good flame retardant synergy, This of flame retardant polyols as structural flame retardant into MPUE can not only improve MPUE, but also can improve the mechanical properties of MPUE. When the content of EG was 20% and the content of PF-2011 was 30%, the oxygen index of MPUE system can reach 33 and UL-94 achieve the V-0 level.