Effect of steady shear deformation on electrically conductive PP/PS/MWCNT composites

Conductive polymeric materials are commonly obtained by adding conductive nanoparticles to blends of immiscible polymers that form a cocontinuous morphology. However, during processing, morphology changes, affecting material properties. This study investigates the impact of steady shear deformation on the morphological and electrical properties of a model system consisting of polypropylene/polystyrene/multiwall carbon nanotubes (MWCNTs). The findings reveal that the deformation results in the coarsening of the blend morphology and disruption of the electrical network, increasing both the rheological and electrical percolation threshold concentrations. The evolution of both electrical and morphological properties depends on MWCNT concentration, strain amplitude, and shear rate. The MWCNT concentration, below a certain level, leads to a disruption in electrical conductivity at high shear rates. However, if the MWCNT concentration is above 1 wt. %, the balance between filler network breakup and nanoparticle diffusion is maintained, resulting in stable electrical conductivity and morphology.