纳米Mg(OH)2-微胶囊红磷/乙烯-乙酸乙烯酯共聚物阻燃复合材料的性能

Properties of nano Mg(OH)2-microencapsulated red phosphorus/ethylene-vinyl acetate copolymer flame-retardant composite

  • 摘要: 以微米Mg(OH)2(mMg(OH)2)、纳米Mg(OH)2(nMg(OH)2)和微胶囊红磷(MRP)为无卤阻燃剂,乙烯-乙酸乙烯酯共聚物(EVA)为聚合物基体,通过熔融共混方法制备了一系列不同阻燃剂含量的Mg(OH)2-MRP/EVA阻燃复合材料,采用极限氧指数、垂直燃烧、锥形量热分析、热分析、SEM、拉伸试验、流变学分析等方法研究了复合材料的阻燃、力学和加工性能。结果表明,Mg(OH)2阻燃剂用量相同时,nMg(OH)2/EVA复合材料的阻燃和抑烟性能比mMg(OH)2/EVA复合材料更好,但当Mg(OH)2用量小于60wt%时,nMg(OH)2/EVA和mMg(OH)2/EVA复合材料的垂直燃烧等级都达不到V-0级。Mg(OH)2本身的阻燃效率较低,nMg(OH)2和MRP对EVA有非常显著的协同阻燃作用,二者掺杂比例适当时可大幅度降低Mg(OH)2的用量。与nMg(OH)2/EVA复合材料相比,nMg(OH)2-MRP/EVA复合材料燃烧时能够生成连续致密的炭层,覆盖在材料表面形成防火屏障,提高其阻燃性能。nMg(OH)2的热分解反应对nMg(OH)2-MRP/EVA复合材料的燃烧性能有极其重要的影响。当nMg(OH)2热分解后再加入到MRP/EVA体系中时,nMg(OH)2-MRP/EVA复合材料的阻燃和抑烟性能均急剧降低。当nMg(OH)2∶MRP∶EVA的质量比为40∶10∶100时,nMg(OH)2-MRP/EVA复合材料同时具有优异的阻燃性能、力学性能和加工性能,可满足实际应用的需要。

     

    Abstract: Using micro Mg(OH)2 (mMg(OH)2), nano Mg(OH)2 (nMg(OH)2) and microencapsulated red phosphorus (MRP) as the halogen-free flame retardants and ethylene-vinyl acetate copolymer (EVA) as the polymer matrix, a series of Mg(OH)2-MRP/EVA flame-retardant composites with different loadings of flame retardant were prepared by melt-compounding. The flame retardancy, mechanical and processing properties of the Mg(OH)2-MRP/EVA composites were investigated by limiting oxygen index, vertical burning test, cone calorimetry, thermal analysis, SEM, tensile test and rheological analysis. The results indicate that both flame retardancy and smoke suppression of the nMg(OH)2/EVA composite are better than that of the mMg(OH)2/EVA composite at the same loading of Mg(OH)2 flame retardant. However, the UL-94 rating of nMg(OH)2/EVA and mMg(OH)2/EVA composites can not reach V-0 rating when the Mg(OH)2 loading is less than 60wt%. The flame retardant efficiency of Mg(OH)2 is low by itself and there is remarkable synergism between nMg(OH)2 and MRP on the flame retardancy of EVA. The loading of Mg(OH)2 can be reduced considerably when nMg(OH)2 and MRP are combined at proper ratio. Comparing with nMg(OH)2/EVA composite, the nMg(OH)2-MRP/EVA composite can produce a continuous and compact char residue layer on its surface, which serves as a barrier against fire and increases fire retardancy. The thermal degradation of nMg(OH)2 has crucial influence on the fire behavior of the nMg(OH)2-MRP/EVA composite. When nMg(OH)2 is pre-pyrolyzed and added to the MRP/EVA composite, both flame retardancy and smoke suppression of the obtained nMg(OH)2-MRP/EVA composite decline sharply. When the mass ratio of nMg(OH)2:MRP:EVA is 40:10:100, the obtained nMg(OH)2-MRP/EVA composite shows excellent flame retardant, mechanical and processing properties simultaneously, which can meet the demand of practical applications.

     

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