Graphite nanoplatelets (GNP) with aspect ratio of around 10⁴ were produced, while avoiding the un-exfoliated micro-pores inherited from expanded graphite. UV/O₃ treatment was employed on the GNP surfaces to improve the interfacial adhesion, which in turn improved the electrical, mechanical and thermo-mechanical properties of GNP/epoxy nanocomposites. GNP/epoxy nanocomposites with good dispersion, improved interfacial adhesion and optimized exfoliation extent of GNP were fabricated, which gives the nanocomposites low percolation threshold of 1 wt% (0.5 vol%) and improved mechanical properties. Vapor phase bromine treatment was employed to improve the electrical properties of GNPs by forming charge transfer between C and Br. Therefore, the electrical conductivity of its nanocomposites was...[ Read more ]

Graphite nanoplatelets (GNP) with aspect ratio of around 10⁴ were produced, while avoiding the un-exfoliated micro-pores inherited from expanded graphite. UV/O₃ treatment was employed on the GNP surfaces to improve the interfacial adhesion, which in turn improved the electrical, mechanical and thermo-mechanical properties of GNP/epoxy nanocomposites. GNP/epoxy nanocomposites with good dispersion, improved interfacial adhesion and optimized exfoliation extent of GNP were fabricated, which gives the nanocomposites low percolation threshold of 1 wt% (0.5 vol%) and improved mechanical properties. Vapor phase bromine treatment was employed to improve the electrical properties of GNPs by forming charge transfer between C and Br. Therefore, the electrical conductivity of its nanocomposites was also increased when the filler content was higher than the percolation threshold, although the percolation threshold was not changed.

Experimental and theoretical studies were aimed to identify critical factors affected the percolation thresholds of carbon nanotube (CNT)/polymer nanocomposites. CNT/epoxy nanocomposites with different CNT dispersion states were produced using different processing conditions, and the corresponding percolation thresholds varied from 0.1 to above 1 wt% (from 0.06 to above 0.64 vol%). TEM, SEM, optical microscope and particle size analyzer were employed to evaluate the dispersion states of CNTs. It was found that critical factors on percolation threshold included disentanglement of CNTs on the nanoscopic scale, uniform distribution of CNTs on the microscopic scale and the aspect ratio of CNTs. Hybrid epoxy nanocomposites containing CNTs and GNPs were fabricated. Synergy effects were found on the electrical conductivity, fracture toughness and thermo-stability.

An improved analytical model based on the average interparticle distance concept is proposed to predict the percolation threshold of conducting polymer composites containing GNPs and CNTs. For GNP/epoxy nanocomposites, the percolation threshold can be predicted based on the geometric shape of GNPs. For CNT/epoxy nanocomposites, the model was further improved by introducing two descriptive dispersion parameters. The correlations between percolation threshold, dispersion states and aspect ratios were identified. The applicability of the model was verified by comparing with experimental data.