Development Of High-Powered Intumescent Flame Retardant Composites

Polyethylene (PE) is widely used in many fields such as cable and wire,electrical and electronics industry, etc. However PE has only a limiting oxygen index(LOI value of 17.8), and is flammable. Therefore, the flame retardancy of PE is veryimportant in order to widen its application areas.At present, the main flame-retardant systems for PE are based on halogen, phosphorus and inorganic hydroxides. For halogenated flame retardants, there are potential damaging effects on environment, and for inorganic hydroxides the properties of the resulting flame-retardant PE materials are deteriorated due to their high loading. Recently, intumescent flame retardants (IFRs) have received a considerable attention because IFRs are of non-halogen, low toxicity, low smoke release and environmentally friendly.This article study effect of intumescent flame retardants and synergistic additives on LDPE composite mechanical properties and flame retardant properties, and develop good halogen-free flame retardant cable. In this paper, the basic properties of ammonium polyphosphate form I (n>30) and ammonium polyphosphate form II (n>1000) were compared, and so were the mechanical property and flame retardant property of the corresponding composites. The effect of the micro capsulated ammonium polyphosphate form II (MCAPP) on the properties of composites was also studied.The research results showed that ammonium polyphosphate form I and II owned different crystal form,polymerization degree, and their thermal stabilities were also different. However, the properties of their corresponding composites were almost the same.By SEM, the compatibility of micro capsulated ammonium polyphosphate form II, and LDPE was found to be better than that of the original ammonium polyphosphate form II and LDPE. The mechanical property of composites was also improved. The component ratio of MCAPP to pentaerythritol in the Intumescent Flame Retardant was optimized, and it was found that the flame retardant effect turned to be satisfactory when the ratio achieved 4/1.In the LDPE-IFR system, ethylene vinyl acetate copolymer (EVA) was used to improve the compatibility of flame retardant and LDPE. The influence of EVA content on the mechanical property and flame retardant property of complex material was studied. The role of EVA and the mechanism were explored, and the reaction conditions were optimized.In the PE-IFR system, the effects of several synergistic agents, which are commonly used in many kinds of intumescent flame retardants, were compared. The rule and mechanism were studied. It was found that the addition of zeolite and zinc borate improved the flame retardant properties of composite a lot, and they were thought to be efficient agents for the PE-IFR system.