含铁层状复合氢氧化物对膨胀阻燃聚丙烯体系的抗滴落协效作用

The anti-dripping synergistic effect of iron-containing LDH with intumescent flame retardant on the properties of polypropylene composites

研究了含铁层状复合氢氧化物(LDH)对膨胀阻燃聚丙烯体系的抗滴落协效作用。采用水热法制备了镁铝LDH(MgAl-LDH)、镁铝铁LDH(MgAlFe-LDH)及镁铁LDH(MgFe-LDH),并采用XRD、FT-IR、SEM的方法对3种LDH进行了表征。采用熔融共混法制备了聚丙烯(PP)/膨胀阻燃剂(IFR)/LDH复合材料,通过极限氧指数、UL94垂直燃烧测试、热失重分析考察了阻燃复合材料的抗滴落性能、热稳定性,采用扫描电镜(SEM)表征了残炭的形貌结构。UL94垂直燃烧测试表明,含Fe3+的LDH,可以显著改善PP/IFR体系的抗滴落性能,添加0.8%(质量分数)的比例,达成UL94V-0(1.6mm)的阻燃剂添加量由23%降至21%。热失重分析表明,各LDH均可催化PP/IFR体系的热降解,同时促进其成炭,从而增强了其在高温区域的热稳定性;其中MgAlFeLDH对材料热稳定性的影响要优于MgFe-LDH,说明LDH中Fe3+有一合适的比例范围,过量的Fe3+则起到反作用。炭层SEM分析表明,各LDH均可改善PP/IFR体系的炭层质量,含Fe3+的LDH协效体系,炭层刚性增强,这可解释其抗滴落的原因。

A study on the effect of iron-containing layered double hydroxides(LDH)on the anti-dripping proper-ties of PP/IFR composites was undertaken.MgAl-,MgAlFe-,MgFe-LDH were synthesized via a hydrothermal method?and subsequently dispersed into PP in combination with an intumescent flame retardant(IFR)by a melt blending process.The anti-dripping and thermal properties of PP composites were evaluated by L()I,UL94vertical burning tests and TGA,the morphologies and structures of char residues were characterized by SEM.The anti-dripping synergistic effect of iron-containing LDH with IFR on the properties of PP composites was proved to be excellent.With the addition of0.8%MgAlFe-LDH or MgFe-LDH,the anti-dripping property of PP composites improved significantly,the ratio of IFR decreased from23%to21%and PP composites can still reach UL94V-〇(1.6mm).TGA results demonstrated that LDH promoted the thermal degradation of PP/IFR.Moreover,LDH promoted the formation of a char layer to enhance the thermal stability in the high temperature range.The char residue of PP/IFR/MgAlFe-LDH samples was highest because the appropriate ratio of Fe3made the balance between the acceleration of thermal decomposition and enhancement of carbonaceous char for-mation.SEM results showed LDH could improve the quality of char layer.Iron-containing LDH increased the rigid of char layer,whichcould explain the reason of anti-dropping synergistic effect.