High Strength Conductive Polyamide 6 Nanocomposites Reinforced by Prebuilt Three-Dimensional Carbon Nanotube Networks

The rapidly growing fields of aerospace, energy, and electronic devices raise the demand for materials with ever-increasing mechanical properties and electrical and thermal conductivity. However, the combination of unusual high performance is difficult to attain. In this study, using prebuilt three-dimensional (3D) closely packed interconnected multiwalled carbon nanotube (MWNT) networks as a backbone for assembly of polymer matrix, a novel, green (solvent-free), and energy-saving method to prepare robust, highly electrical, and thermal conductive polyamide nanocomposites is reported. The as-prepared nanocomposites exhibit significant enhancements of 16 orders of magnitude in electrical conductivity and 505% in thermal conductivity, which mainly benefits from the contributions of closely packed 3D networks and conductive pathways of carbon nanotubes. In addition, even at a high MWNT loading of 25 wt %, the as-prepared nanocomposites still possess a high tensile strength of 99.4 MPa and Young’s modulus of 5.3 GPa. The performance of the as-prepared nanocomposites exceeds that of most of the composites, which confirms the potential of the prebuilt MWNT network method for fabricating robust and highly conductive nanocomposites and the importance of good interconnectivity of nanofillers–nanofillers and nanofillers–matrix. The special fabrication method could open up a broad range of possibilities for aerospace, conducting elements, and structural nanomaterials, as well as electronic components with the requirements of heat dissipation, mechanical strength, thermal repair, corrosion resistance, and so on.