EVA/纳米SiO_2阻燃复合材料的性能研究

Investigation on the performance of EVA/Nano-SiO_2 flame retarded composite

以乙烯-醋酸乙烯共聚物(EVA)为基体,将聚磷酸铵(APP)和季戊四醇(PER)组成的膨胀阻燃体系(IFR)与纳米SiO_2复配使用,熔融共混制备复合材料.并通过对复合材料硬度,力学性能及阻燃性能的测试,研究不同纳米SiO_2及IFR添加量对复合材料性能的影响.通过扫描电镜(SEM)对复合材料燃烧后所形成炭层形貌进行分析.结果表明,纳米二氧化硅在体系中的添加,在一定程度上有利于复合材料力学性能及熔滴现象的改善.但其作为协效剂的用量在阻燃体系中较高时,不利于复合材料阻燃等级的提高.复合材料的邵氏硬度较纯EVA有明显的提高.当纳米SiO_2及IFR的总添加质量分数为25%,且纳米SiO_2添加质量分数为6%时,复合材料的拉伸及燃烧综合性能最优,拉伸强度可达到10.4 MPa,极限氧指数达到27.7%,UL-94燃烧等级可以达到V-1.SEM结果表明,随着IFR添加量的增加,复合材料燃烧后形成的炭层越致密.

A kind of intumescent flame retarded ethylene vinyl acetate （EVA） based compos-ite was prepared by melt blending. Intumescent flame retardant （ IFR ） was constituted by ammonium polyphosphate （APP） and pentaerythritol （PER）, and nano-SiO2 was used as a synergistic agent. The shore hardness, mechanical performance and flame retardant properties of composites were investigated . Furthermore, the surface of residual char after combustion was studied by scanning electron microscope （SEM）. The incorporation of nano-SiO2 in flame retardant system, favored the improvement of mechanical performance and melt drip-ping phenomenon in a certain degree . However^as a kind of synergistic agent, when the nano- SiO2 loading was maintained within a relatively high level,the flame retardant grade of com-posite might be restricted. Experimental data showed that the hardness of composite was im-proved significantly compared with pure EVA. The balanced properties between mechanical performance and flame retardant property of composite could be achieved when the nano- SiO2and IFR loadingwere 6 wt% and 19wt% , respectively. Under this formula,the limiting oxygen index （LOI） was 27. 7 % the tensile strength of composite was 10. 4 MPa , and UL-94 V-1 rate could be achieved. SEM images indicated that with the increasing IFR loading,thesurface of residual char would become compact,smooth and with less cracks.