Structure and properties of PP-MWCNTs/HDPE composites with anisotropic conductivity

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.