氮化硼纳米片/氢氧化镁/聚乙烯复合材料导热性能研究

Study on Thermal Conductivity of BNNs/Mg(OH)_(2)/PE Composites

以低密度聚乙烯(LDPE)为基体材料,选用氮化硼纳米片(BNNs)作为第一掺杂填料,选取氢氧化镁(Mg(OH)_(2))作为第二填料,基于熔融共混法制备多填料结构绝缘复合材料,研究了常温常压下两种填料掺杂量对不同厚度的复合材料热导率的影响。结果表明:在多填料复合体系中,Mg(OH)_(2)会改变BNNs在基体中的取向度、连接度从而影响复合材料的热导率。3种试样厚度下高填量的Mg(OH)_(2)均会增强复合材料的轴向热导率。薄厚度下Mg(OH)_(2)的掺入不利于复合材料径向热导率的提升。较厚厚度下,适量的Mg(OH)_(2)能够增强复合材料的径向导热性能,当BNNs的质量分数为20%,Mg(OH)_(2)的质量分数为40%时,复合材料的热导率最高可达纯LDPE热导率的12倍。

In this paper,low density polyethylene(LDPE)was used as the matrix material,boron nitride nanosheets(BNNs)was selected as the first doping filler,magnesium hydroxide(Mg(OH)_(2))was selected as the second filler,and an insulating composites with multi filler structure was prepared by melt blending method.The effects of two filler contents on the thermal conductivity of the composites with different thickness were studied under normal temperature and pressure.The results show that the Mg(OH)_(2)can change the orientation and connection of BNNs in matrix,so as to affect the thermal conductivity of composites.High amount of Mg(OH)_(2)can enhance the axial thermal conductivity of the composites with three thicknesses.The addition of Mg(OH)_(2)is not conducive to improve the radial thermal conductivity of the composite with thin thickness.Appropriate amount of Mg(OH)_(2)can enhance the radial thermal conductivity of the composite with thicker thickness.When the mass fraction of BNNs is 20%,the mass fraction of Mg(OH)_(2)is 40%,the thermal conductivity of the composite can reach 12 times bigger than that of pure LDPE.