Structure and properties of PP-MWCNTs/HDPE composites with anisotropic conductivity
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摘要: 各向异性导电高分子复合材料(ACPCs)因其独特的各向异性导电特性在许多领域得到广泛应用。本文以高密度聚乙烯(HDPE)、聚丙烯(PP)和多壁碳纳米管(MWCNTs)为原料,通过三层吹膜技术制备中间层导电、内外两层绝缘的三层复合膜,再利用热压成型技术制备具有交替微层结构的各向异性导电PP-MWCNTs/HDPE复合材料。综合利用DSC、偏光显微镜(POM)、SEM、TEM、拉伸性能及导电性能测试等手段研究了复合材料的结构和性能。结果表明:PP绝缘层和MWCNTs/HDPE导电层交替排列,没有分层、熔并等结构缺陷,界面结合良好;PP-MWCNTs/HDPE复合材料在X方向和Y方向具有优异的导电性能(电阻率低至1.6 Ω·m),比Z方向的电阻率低6~9个数量级;交替微层结构的存在增强了复合材料的力学性能,进一步拓宽了导电复合材料的应用范围。Abstract: The anisotropic conductive polymer composites (ACPCs) have been applied in many fields owing to their unique anisotropic conductive property. In this article, a three-layer composite membrane with conductive middle layer and insulative inner and outer layers was prepared by three-layer film blowing technique, using high-density polyethylene (HDPE), polypropylene (PP) and multi-walled carbon nanotubes (MWCNTs) as raw materials. PP-MWCNTs/HDPE composite with anisotropic conductivity and alternating microlayers were then fabricated by hot-compression molding technique. A combination of DSC, POM, SEM, TEM, tensile and conductivity test was performed to provide a comprehensive analysis of structure and properties. The results show that the alternating arrangement of insulative PP layers and conductive MWCNTs/HDPE layers is successfully fabricated, and there is no structural defect (layer breakup or interlayer connection) in the microlayers, which indicates good adhesion in such multilayered structure. The PP-MWCNTs/HDPE composites exhibit excellent electrical conductivity in X and Y direction with electrical resistivity as low as 1.6 Ω·m, that almost 6-9 orders of magnitude lower than that in Z direction. The composites also demonstrate enhanced mechanical property, broadening the application field of conductive composite materials.
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表 1 PP-MWCNTs/HDPE复合材料的拉伸性能
Table 1. Tensile properties of PP-MWCNTs/HDPE composites
Sample E/GPa σ/MPa Wb/(MJ·m−3) 10 layers 19.70 14.41 0.84 15 layers 21.01 22.41 1.24 20 layers 24.76 23.12 1.83 25 layers 43.81 30.56 2.78 30 layers 50.91 34.14 2.99 Notes: E—Young's modulus; σ—Tensile strength; Wb—Toughness. -
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