纳米Al_2O_3分布对Al_2O_3/PE-EVA复合材料导热性能与力学性能的影响

Effects of nano Al_2O_3 distribution on thermal conductivity and mechanical property of Al_2O_3/PE-EVA composites

旨在将纳米Al2O3分散在聚乙烯(PE)和乙烯醋酸乙烯共聚物(EVA)的共混物中,构建具有选择性分布结构的局域高粒子浓度导热复合材料。采用纳米Al2O3为导热填料,以PE和EVA为基体树脂,使用熔融共混法制备了Al2O3/PE-EVA导热复合材料。利用选择性溶液萃取方法和SEM研究了PE-EVA共混物的相结构及纳米Al2O3在共混物中的分布,评价了Al2O3/PE-EVA复合材料的导热性能与力学性能。结果表明:在PE与EVA质量比为1∶1时可获得具有两相共连续结构的共混物;在两相共连续PE-EVA共混物中引入纳米Al2O3后,发现纳米Al2O3主要分布在PE相中;纳米Al2O3的分布行为及共连续结构的形成有助于提高复合材料的导热性能,在纳米Al2O3质量分数为50%时,与Al2O3/PE复合材料相比,具有选择分布和相连续结构的Al2O3/PEEVA复合材料的热导率提高了21.2%;随着纳米Al2O3质量分数的增加,Al2O3/PE-EVA复合材料的拉伸强度与Al2O3/PE复合材料的拉伸强度相近,同时由于EVA相的增韧作用,其断裂伸长率优于Al2O3/PE复合材料。

This paper aims at dispersing nano A12O3in polyethylene（PE） and ethylene vinyl acetate copolymer （EVA） blends to build thermal conductive composites with high local particle concentration and selective distribution structure. With nano AlzO~ as thermal conductive filler, PE and EVA as matrix resin, A1203/PE-EVA thermal conductive composites were prepared by melt blending method. The phase structure of PE-EVA blends and distribu- tion of A12O3 in blends were investigated by selective solution extraction method and SEM. The thermal conductivity and mechanical properties of A12 03/PE-EVA composites were evaluated. The results show that blends with two- phase co-continuous structure are obtained at PE to EVA mass ratio of 1 ： 1. By introducing A12O3 into PE-EVA two-phase co-continuous blends, A12O3 is mainly dispersed in PE phase. The distribution behavior of A12O3 and the formation of co-continuous structure are helpful to improve the thermal conductivity of composites. 21.2% increase of thermal conductivity is obtained for A1203/PE-EVA composites with selective distribution and co-continuous structure, in comparison to that of A1203/PE composites at A1203 mass fraction of 50% With the increase of A1203 mass fraction, the tensile strength of A12O3/PE-EVA composites tends to be similar to that of A12O3/PE composites. The elongation at break ofA12O3/PE-EVA composites is also superior than that of A12O3/PE compos- ites thanks to the toughing effect of EVA phase.