Study Of High-powered Halogen-free Flame Retardant Polyethylene Composite

Polyethylene(PE) is widely used in field of cable and wire, because of its great mechanical properties, higher mass resistivity and lower dielectric dissipation fraction. PE belongs to flammable material, so it need to modified with flame retardant. The application of halogen flame retardant has been resisted, because it release hadrogen halide during combustion, so halogen-free fire retardant PE come to be a hot spot. Compared with halogen flame retardant, the efficiency of halogen-free fire retardant is lower with the drop of mechanical properties. So it is essential to develop a fire retardant PE composite with higher efficiency, environment-friendly and excellent comprehensive performance. Main contents and results are concluded as follows:(1) Mixed melamine coated ammonium polyphosphate(MAPP) with high degree of polymerization and pentaerythritol(PER) into intumescent flame retardant. Synergy of MAPP and PER, and their influence on properties of PE have been researched. The result indicated that PE has a better fire retardant property when MAPP/PER=2/1. Mixed intumescent flame retardant with MAPP/PER=2/1, and prepared fire-retardant composite(PE/IFR). The LOI value of PE/IFR can reach to 25.5% when content of IFR is 30%, but the mechanical properties of composites dropped significantly. Futher analysis showed that MFR of PE could be improved by IFR. It can increase the heat-resistant deformation temperature, and widen the scope of thermal degradation temperature as well.(2) Na-MMT, OMMT and nylon6 were used in PE/IFR composites as flame retardant synergistic agents. The synergistic fire retardant action, thermal stability, and shape of charcoal layer were studied by the use of limiting oxygen index(LOI), thermogravimetric analysis(TGA), scanning electronic micrograph(SEM),etc. The structure of PE/IFR/MMT composites were researched by X-ray. The result showed that appropriate contents of OMMT and PA6 could lead to better flame retardant synergy of PE/1FR composites, catalyzed the process of char forming and contribute to the high-quality carbon formation.(3) Reinforce PE/Mg(0H)2 composite with SiC>2 deposited and coupling agent treated Magnesium salt whisker. The research showed that the mechanical and heat-resistant deformation properties of composites could be effectively improved by M-HOS. Size refinement of IFR could improve the properties of mechanical and fire retardant. The LOI value was increased by 1.5% when IFR content is 28%.