Mechanical and electrical properties of multi walled carbon nanotube/ABC block terpolymer composites

Composites of multi-walled carbon nanotubes (MWCNTs) in ABC block terpolymer matrices of different compositions are studied. The composites were obtained by dispersion of MWCNTs in poly(styrene-block-butadiene-block-methyl methacrylate) (SBM) in a selective solvent for the M block, followed by solvent evaporation and compression molding. The structures of the MWCNT/SBM composites are investigated by transmission electron microscopy. The processing conditions, i.e. solvent cast or compression molding, induce different non-equilibrium microstructures and the MWCNTs modify the SBM organization only locally. We show that by fixing the processing procedure we are able to obtain samples with reproducible microstructure and properties. The electrical conductivity thresholds of these composites are lower than 1 wt.%. The reinforcing effect of the MWCNTs measured by dynamical mechanical analysis is mainly related to the SBM microstructures of the matrix and to the MWCNT dispersion quality.