| Recently, inorganic flame retardant have received extensive interest due to its environmentally friendly, the absorption of heat and production of a large number of non-flammable gas when heated, further more, the residue after decomposition is stable enough to be used as a barrier covering the surface of material. In this paper, a novel of aluminum hypophosphite was synthesized based on sodium hypophosphite and aluminium chloride, and then it was added into polyurethane elastomer to study the influence of the novel aluminum hypophosphite toward polyurethane elastomer. Meanwhile, there kind of molybdenum trioxide with different morphologies was synthesized based on ammonium heptamolybdate and nitric acid through hydrothermal method and high-temperature calcination, respectively. And the influences of there kind molybdenum trioxide to polyurethane elastomer were studied by applying them in the polyurethane elastomer.(1) A novel aluminum hypophosphite was synthesized through hydrothermal method, and the influence of reaction conditions including solvent, temperature, time, concentration of reactants and quantity of PVP for the aluminum hypophosphite particle size was studied by changing these conditions. Result shows that: the synthesized aluminum hypophosphite was spherical, and the minimum aluminum phosphate microspheres particle size of 5 um was obtained when solvent is water and ethanol with volume ratio of 1:1, temperature is 230℃,time is 7h, the concentration of AlCl3 is 0.1 mol/L and the addition of PVP is 1.0g(mass ratio of 1:1 with AlCl3).(2) The hydrothermal aluminum hypophosphite and the precipitation aluminum hypophosphite were added to the polyurethane elastomer, respectively. The flame retardant properties, thermal stability and mechanical properties of the PUE with different kinds of AHP added were studied. The result show that the limited oxygen index(LOI)of the PUE increased to 28.5 vol% with the addition of 5% hydrothermal AHP, PHRR decreased by 80.1%.Compared with the PUE including same amount of precipitation AHP, the PHRR decreases by about 6%. Hydrothermal AHP could improve the char yield which provides better flame retardancy for PUE. Meanwhile, the hydrothermal AHP-added PUE has better mechanical properties than that with precipitation AHP added.(3) Molybdenum oxide microrods, nanofibers and nanoplates were synthesized through hydrothermal and high temperature calcination method,respectively. The influences of different conditions toward molybdenum oxide morphology were studied by changing temperature, time and acidity and so on. the results show that uniform morphology molybdenum oxide microrods were obtained through hydrothermal method with temperature of 180℃, reaction time of 20 h and acidity of 6. molybdenum oxide nanofibers with uniform morphology were obtained under 180℃,24 h and 25 acidity. Moreover, when nanofibers were used as precursor, uniform nanoplates were obtained through high temperature calcination under 700℃,3h.(4) Molybdenum oxide microrods and nanofibers obtained through hydrothermal and nanoplates obtained through high temperature calcination method were added into polyurethane elastomer to study the influences of different kinds of molybdenum oxide toward the polyurethane elastomer’s flame retardancy, smoke suppression and mechanical properties.the results show that molybdenum oxide nanofibers possess the best flame retardancy to lead a 60% decrease of PHRR of polyurethane composites with 1wt% addition, the effect of applying nanoplates was the second and nanofibers was the worst. Moreover, the best smoke suppression effect was received by applying3 wt% molybdenum oxide nanoplates to make the smoke density decreased by 26.1%, the effect of nanofibers was the second and the worst was microrods. Meanwhile, compared with microrods, nanoplates and nanofibers possessed better mechanical properties. |
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