Wei-Qin Zhang

Double-segregated carbon nanotube–polymer conductive composites as candidates for liquid sensing materials

Double-segregated conductive polymer composites were fabricated as candidates for liquid sensing materials; these composites exhibited ultralow percolation (∼0.09 vol%), good reproducibility, and a large liquid sensing capacity (∼8 × 104%) with a balanced electrical conductivity (∼1 S m−1).

Segregated Conductive Ultrahigh-Molecular-Weight Polyethylene Composites Containing High-Density Polyethylene as Carrier Polymer of Graphene Nanosheets

This article reports a novel conductive ultrahigh-molecular-weight polyethylene (UHMWPE) composite with a segregated and double percolated structure, in which graphene nanosheets (GNSs) form prefect conductive pathways in the high-density polyethylene (HDPE) and the GNS/HDPE component forms continuous conductive layers at the interface between the UHMWPE granules. The combination of segregated and double-percolated GNS conductive network achieved an ultralow percolation of 0.05 vol. %. Structural observations and the determination of the critical exponent t-value obtained from the classical threshold mechanism indicate the formation of a two-dimensional GNS network in GNS/HDPE/UHMWPE composites. Comparison of the electrical performance of GNS and CNT-filled segregated composites indicated that the geometry of the conductive nanoparticles can greatly affect the dimensionality of the segregated conductive network.

A Conductive Carbon Nanotube-Polymer Composite Based on a Co-continuous Blend

A conductive carbon nanotube (CNT) based polymer composite was constructed in which the conductive network utilized the selective distribution of CNTs in a co-continuous phase polymer blend. CNTs were first uniformly coated on the surface of polyethylene (PE) fine particles through alcohol assisted dispersion under ultrasonication, and then the CNTs coated PE particles were melt compounded with polycarbonate (PC). The theoretical prediction from both thermodynamics and kinetics indicated the CNTs mainly stayed at the interface between PC and PE. Rheological measurements and scanning electron microscopy (SEM) and optical microscopy (OM) observations provided the evidences for the selective distribution of CNTs and revealed the transition from the dispersed/matrix phase structure to the co-continuous phase structure at 50 wt% of PC. As PE and PC formed co-continuous phases, the CNTs formed a perfect conductive network on the phase interfaces, which resulted in a percolation threshold between 0.3 and 0.5 vol%, a relatively low value for CNTs filled thermoplastic composites reported in the literature.