巴旦木壳/高密度聚乙烯基复合材料的阻燃性能

Flame retardancy of almond shell/high density polyethylene composites

为有效利用食品加工行业产生的巴旦木果实外壳,用高密度聚乙烯(HDPE)、巴旦木壳、FRW阻燃剂为原料合成一种具有阻燃特性的复合材料。结果表明,巴旦木外壳存在丰富的孔隙结构,能够在较短时间内吸附较多的阻燃剂;当巴旦木壳载药率为15%时,巴旦木壳/HDPE复合材料的力学性能较好,与未添加阻燃剂的复合材相比弯曲强度提升10.93%,拉伸强度提升8.19%,弹性模量提升0.88%,冲击强度提升29.44%。扫描电子显微镜观察显示,巴旦木壳的细胞壁上均匀分散着阻燃剂;当巴旦木壳载药率为5%,15%,25%时,巴旦木壳/HDPE复合材料的极限氧指数分别为25.7%,26.5%,27.1%,高于相同条件下制备的杨木/HDPE复合材料。锥形量热仪检测结果表明,巴旦木壳/HDPE复合材料相比杨木/HDPE复合材料阻燃性能更好。当载药率为15%时,巴旦木壳/HDPE复合材料的最高热释放速率、平均热释放速率、总热释放量、平均有效燃烧热、点燃时间分别为256.12 kW/m^2、147.50 kW/m^2、73.78 MJ/m^2、21.47 MJ/kg、27 s,具有较好的阻燃性能。热重分析显示,巴旦木壳/HDPE复合材料具有较好的热稳定性。

Wood-plastic composites(WPC)are made of wood fibers and polymers by melt-compositing,using technologies of extrusion,injection or molding,etc.It combines the advantages of wood and plastic by addressing the drawbacks of each individual material.In addition to wood,WPC can be also prepared using other biomass materials,such as rice husk,bagasse and straw.However,the raw material plant fibers and plastics are both flammable and have poor flame-retardant properties.Although the use of almond shells(Als)has been explored to some extent,there are limited reports on the preparation of the flame-retardant composites from almond shells.The currently used flame retardants are halogen,phosphorus,boron,intumescent flame retardants and inorganic hydroxides.FRW is a phosphorus and boron compound flame retardant,composing of high purity guanylurea phosphate(GUP),boric acid and a small amount of auxiliary agents.In order to effectively utilize almond shell,the high density polyethylene(HDPE),almond shell and FRW flame retardant were used to prepare flame retardant composites.The experimental results showed that there were plenty of voids in the almond shell,which would adsorb more flame retardants in a short time period.The flexural strength,tensile strength,flexural modulus and impact strength of the almond shell/high density polyethylene(Als/HDPE)composites were increased by 10.93%,8.19%,0.88%and 29.44%,respectively,compared with the control samples.The examination of the scanning electron microscope showed that the FRW flame retardant was evenly dispersed on the cell walls of the almond shell.The limiting oxygen index of the Als/HDPE composites were 25.7%,26.5%and 27.1%when the flame retardant loading rate in almond shell were 5%,15%and 25%,respectively.In addition,the limiting oxygen index of Als/HDPE composites was higher than that of poplar/HDPE composites under the same conditions.The testing results of the cone calorimeter showed that the flame retardancy of Als/HDPE composites was better than that of poplar/HDPE composites.When the flame retardant loading rate of almond shell was 15%,Als/HDPE composites had maximum heat release rate of 256.12 kW/m 2,the average heat release rate of 147.50 kW/m 2,the total heat release of 73.78 MJ/m 2,the average effective combustion heat of 21.47 MJ/kg and the ignition time of 27 s.It was indicated that Als/HDPE composites had good flame retardancy.The thermogravimetric analysis showed that the thermal stability of Als/HDPE composites was better.