Shear influenced network dynamics and electrical conductivity recovery in carbon nanotube/epoxy suspensions

Destruction and re-formation of conductive filler networks in a low viscous carbon nanotube (CNT)/epoxy system were investigated by online rheological, electric and optical measurements. A combined experimental setup allowed for a well-defined shear deformation of the suspension which led to a decrease in the electrical conductivity by three orders of magnitude due to network destruction and agglomerate size reduction. Subsequent to the shear induced deformation, a complete recovery of the conductivity was observed. In contrast, persistent changes in the microstructure after different shear treatments have been observed. A simple model combining classical electric percolation and time-dependent cluster aggregation was adopted to give a quantitative description of the recovery process. Recovery and aggregation process of CNT in epoxy are comparable with the behaviour in high viscous matrix systems.