Super-tough conducting carbon nanotube/ultrahigh-molecular-weight polyethylene composites with segregated and double-percolated structure

Abstract

Super-tough conducting carbon nanotube (CNT)/ultrahigh-molecular-weight polyethylene (UHMWPE) composites were prepared by a facile method; a very small amount of high-density polyethylene (HDPE) was used as the percolated polymer phase to load the CNTs. A structural examination revealed the formation of unique conductive networks by combination of the typical segregated and double-percolated structure, in which the fully percolated CNT/carrier polymer layers were localized at the interfaces between UHMWPE granules. Owing to the synergistic effect of the segregated and double-percolated structures, only 0.3 wt% of CNTs can make the composite very conductive. More interestingly, after the addition of only 2.7 wt% of HDPE, the ultimate strain, tear strength, and impact strength reached 478%, 35.3 N and 58.1 kJ m⁻², respectively; these corresponded to remarkable increases of 265%, 61.9%, and 167% in these properties compared with the conventional segregated materials. These results were ascribed to the intensified interfacial adhesion between UHMWPE granules, which resulted from the strong inter-diffusion and heat-sealing between the HDPE and UHMWPE molecules. A model was proposed to explain the outstanding ductility and toughness properties of the segregated and double-percolated CPC material.