Study On Synergistic Retarding Effect Of Attapulgite And Intumescent Flame Retardant On Linear Low Density Polyethylene/Ethylene-vinyl Acetate Copolymer

Linear low density polyethylene and ethylene vinyl acetate copolymer(LLDPE/EVA) as plastics of wire and cable materials are used widely in industry, however the limit oxygen index of materials is only 17%, and highly combustible. Halogen-containing flame retardants are common flame retardants for wire and cable materials, but they are harmful to the environment, inorganic flame retardant is bad for mechanical property of materials, so developing new efficient environmentally friendly flame retardants have been researched hot spots. This paper lays emphasis on the research of the flame resistant that attapulgite(ATP) cooperate with intumescent flame retardant(IFR) to LLDPE/EVA materials, a series of flame retardant composites were prepared by melting blending, the effects of properties of inflaming retarding on three kinds of flame retardants were discussed. The properties of composite materials were characterized and analyzed by horizontal flammability tests, vertical flammability tests, limit oxygen index tests, scanning electron microscopy(SEM), thermal gravimetric analyzer(TGA), universal testing machine etc.As for ATP/LLDPE/EVA composite materials, the study showed that, the flame retardant properties?tensile strength and residual carbon of the composites were enhanced and the elongation at break were reduced with the contents of ATP increasing. The samples foamed and expanded during the combustion processed. The thermal stability of the composites were enhanced both in the atmosphere of nitrogen and air with the increasing of ATP.As for IFR/LLDPE/EVA composite materials, the study showed that, with the contents of EG increasing, flame retardant properties was increased at first and decreased afterwards and the tensile strength and the elongation at break were reduced. When the ratio of ammonium polyphosphate?melamine and expanded graphite was 2:1:2, the content of flame retardant was 30%, the composite materials were the best flame retardant properties, the charred layers of composite materials possessed the perfect compact structure at the same time, and the vertical flammability tests could reach up to FV-0, and LOI could reach up to 29.0%. In the atmosphere of air, the composite materials formed carbon more easily compared with the atmosphere of nitrogen.As for ATP/IFR/LLDPE/EVA composite materials, the study showed that, with the contents of synergistic flame retardant ATP, flame retardant properties was increased at first and decreased afterwards, and the tensile strength and the elongation at break were reduced. When the ratio of synergistic flame retardant ATP was 4%, the composite materials were the best flame retardant properties, the charred layers of composite materials possessed the perfect compact structure at the same time, and the vertical flammability tests could reach up to FV-0, and LOI could reach up to 29.5%. In the atmosphere of air, the composite materials formed carbon more easily compared with the atmosphere of nitrogen. The mechanical properties improved when the composite materials treated with the silane coupling agent.