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. (C) 2010 Elsevier Ltd. All rights reserved.