层状阻燃结构对PBT/IFR复合材料性能的影响

通过熔融共混和模压成型技术制备了聚对苯二甲酸丁二酯(PBT)/膨胀型阻燃剂(IFR)共混和层状复合材料,其中层状复合材料为3层阻燃结构,内层为非阻燃层(纯PBT),内层外面两层为阻燃层(PBT/IFR)。通过UL94垂直燃烧、极限氧指数(LOI)以及拉伸和冲击性能测试对比分析了两种复合材料的阻燃性能和力学性能。结果表明,与PBT/IFR共混复合材料相比,PBT/IFR层状复合材料的阻燃性能提高幅度更大,虽然低IFR含量下其力学性能低于共混复合材料,但随着IFR含量增加,力学性能下降幅度更小。当层状复合材料中的阻燃层/非阻燃层/阻燃层的厚度比为1.5 mm/1 mm/1.5 mm,即IFR质量分数为22.5%时,其拉伸强度、断裂伸长率和冲击强度与相同IFR用量下的共混复合材料相当,而阻燃性能与IFR质量分数为30%的共混复合材料相当,其UL 94阻燃等级达到V–0级,LOI提高到24.4%。这表明,采用层状阻燃可控受限结构,可在较低的IFR用量下更好地提高PBT/IFR复合材料的阻燃性能,同时减缓了力学性能下降的幅度。

Inlfuences of Layered Flame Retardant Structure on Properties of PBT/IFR Composites

Blended and layered PBT/IFRcomposites were prepared by melting blending and compression molding technol-ogy. The layered PBT/IFR composites has three layersflame retardant structure,the middle layer is nonflame retardant layer (pure PBT),two outer layers areflame retardant layers (PBT/IFR). Theflammability,mechanical properties of the two composites were analyzed by the UL 94 vertical combustion,limiting oxygen index (LOI),tensile and impact properties test. The results show that compared with the blended composites,theflame retardancy of the layered composites is more promoted,and although the mechani-cal properties of the layered composites are lower than those of the blended composites at low IFR content,with increasing IFR con-tent,the decline of the mechanical properties of the former is less. When the ratio of layer thickness of theflame retardant layer/non flame retardant layer/flame retardant layer is 1.5 mm/1 mm/1.5 mm ( the mass fraction of IFR is 22.5%),the tensile strength, elongation at break and impact strength of the layered composites are equal to the blended composites with the same content of IFR, theflame retardancy is equal to the blended composites with 30% IFR,the UL 94flame retardant rating reaches V–0 and the LOI value increases to 24.4%. These suggest that using the controllable constrained layeredflame retardant structure,theflame retardancy of PBT/IFR composite can be greatly promoted with less addition of IFR and the decline of mechanical properties are reduced.