Surface treatment of multiwalled carbon nanotubes and the formation of the multiscale conductivity network in long carbon fiber reinforced polypropylene

Abstract Surface treatment on multiwalled carbon nanotubes (MWCNTs) by covalent H ₂ O ₂ and non‐covalent Triton X‐100 for the dispersion of carbon nanotubes in long carbon fiber reinforced polypropylene matrix was proposed to fabricate the electrically conductive long fiber reinforced polypropylene composites by melt mixing. Their mechanical, thermal, rheological properties, as while as their morphology and electrical conductivity, were systematically investigated. The combination of micro‐scale long carbon fibers and nano‐scale carbon nanotubes are co‐existed in the polypropylene matrix. A multiscale conductive network is formed which great favor of the electrical conductivity of the composites. The results showed that the volume and surface resistivity of the sample with 4 wt.% MWCNTs addition is only 26.97 kΩ cm ^‑1 and 4.82 kΩ, respectively. The surface treatment showed positive effects on the mechanical, thermal, dynamic mechanical, and rheological properties. Compared to Triton X‐100, covalent H ₂ O ₂ treated MWCNTs exhibited more significant improvement on the structure and properties of the long carbon fiber reinforced polypropylene.