以石塑为表层的WF/HDPE夹层结构复合材料的性能

Performance of sandwiched WF/HDPE composites with stone-flour/HDPE surface layer

木塑复合材料是由木纤维和塑料复合而成的一种绿色环保材料,但由于木纤维与塑料易燃,因此需要提升木塑复合材料的阻燃性能。本研究将聚磷酸铵和木质素复配作为阻燃剂,加入表层的石塑复合材料中,以木粉/高密度聚乙烯(WF/HDPE)复合材料作芯层,采用先熔融造粒后模压成型的方式制备了夹层结构阻燃复合材。与WF/HDPE复合材相比,具有石塑和阻燃石塑表层的夹层结构复合材的极限氧指数明显增大,垂直燃烧阻燃等级均达到最佳的V-1级别。扫描电子显微镜观察显示,加入聚磷酸铵和木质素的石塑表层协同成炭效果好,炭层更加厚实致密,对芯材保护作用强。锥形量热仪测试表明,与WF/HDPE复合材相比,以纯石塑为表层的SF/HDPE-1夹层结构复合材总热释放量下降了6.3%,总烟释放量下降了39.7%;以木质素/聚磷酸铵/石塑为表层的SF/A/L/HDPE-1夹层结构复合材总热释放量下降了21.6%,总烟释放量下降了60.2%。同时,相较于WF/HDPE复合材料,以纯石塑为表层的SF/HDPE-1夹层结构复合材拉伸强度提高了21.1%,弯曲强度提高了17.9%;以木质素/聚磷酸铵/石塑为表层的SF/A/L/HDPE-1夹层结构复合材拉伸强度几乎不变,弯曲强度提高了7.4%。试验表明,所开发的夹层结构复合材阻燃性大幅度提升,并具有良好的力学性能。

Wood plastic composites is a green material made from wood fibers and plastics,but the flammability of wood fibers and plastics limits their use in certain applications.To improve the flame retardant performance of WPC,this study utilized ammonium polyphosphate and lignin as flame retardants in the surface layer of stone-plastic composite materials.The core layer of the composite material was made of wood flour and high-density polyethylene(WF/HDPE),while the sandwich structure composite material was created using a melt and granulation method followed by molding.The sandwich structure composite material with a stone-plastic and flame-retardant stone-plastic surface layer showed a significant increase in limiting oxygen index and the flame-retardant grade of vertical combustion reached the best V-1 level when compared to WF/HDPE composite materials.The scanning electron microscopy(SEM)showed that the surface layers of stone plastic with ammonium polyphosphate and lignin had a good synergic carbon formation effect,and the carbon layer was thicker and denser compared to the other layers,which had a strong protective effect on the core material.Cone calorimetry tests showed that the total heat release and total smoke release of the SF/HDPE-1 interlayer structure composite material with a pure stone-plastic surface layer decreased by 6.3%and 39.7%,respectively,compared with WF/HDPE composite materials.The total heat release and total smoke release of the SF/A/L/HDPE-1 interlayer structure composite material with a lignin/ammonium polyphosphate/stone-plastic surface layer decreased by 21.6%and 60.2%,respectively.Additionally,compared with WF/HDPE composite materials,the SF/HDPE-1 interlayer structure composite material with a pure stone-plastic surface layer demonstrated a 21.1%increase in tensile strength and a 17.9%increase in flexural strength,while the SF/A/L/HDPE-1 interlayer structure composite material with a lignin/ammonium polyphosphate/stone-plastic surface layer showed almost no change in tensile strength and a 7.4%increase in flexural strength.Overall,this study successfully developed an interlayer structure composite material that significantly improved flame retardancy and had good mechanical properties.The use of ammonium polyphosphate and lignin as flame retardants in the surface layer of WPC is a promising approach to increase the safety of WPC in applications where fire is a concern.