Low Viscosity Processing using Hybrid CNT-coated Silica Particles to Form Electrically Conductive Epoxy Resin Composites

Hybrid particles of multiwall carbon nanotubes (CNTs) grafted onto silica gel were shown to provide a low viscosity processing route to forming electrically-conductive epoxy resin composites. Rheological studies showed the viscoelastic shear moduli of epoxy resin suspensions containing these particles (named SG6_3) remained within the same order of magnitude as that of the neat resin at ≤5 wt% loading (containing up to 1.65 wt% of grafted CNTs). Whereas, the addition of 1.65 wt% of discrete (non-grafted) CNTs into the same resin increased shear moduli by up to seven orders of magnitude. The complex viscosities of suspensions containing ≤5 wt% of SG6_3 remained essentially unchanged, whereas an increase of up to five orders of magnitude resulted upon the addition of 1.65 wt% of non–grafted CNTs. Whilst rheological studies showed SG6_3 did not form a percolated network at levels ≤5 wt%, addition of only 2 wt% (containing 0.66 wt% CNT) was found to form an electrically–conductive percolated network in an epoxy resin composite with conductivity ∼ 10−4 S/m.