Experiment and theory study on the electrical property of MWCNT filled thermoplastic polyurethane bilayer composites with tunable layer thickness ratios

Abstract

The thermoplastic polyurethane (TPU)/multi-walled carbon nanotubes (MWCNTs) filled TPU (cTPU) bilayer composites with tunable layer thickness ratios were fabricated via layer-assembly coextrusion, while keeping the filler loading in whole composite at 1 wt%. The parallel circuit model was used to predict the electrical resistivity of bilayer composites, but the theoretical value was always lower than the experimental result. It was revealed that the predicted deviation originated from the particle transfer at interface and gradually disappeared with the enhanced migration of MWCNTs from cTPU into TPU. Then, the model was modified with a consideration of particle transfer and applied to explain the evolution of predicted deviation. Unlike the blend composite with the same composition exhibiting an insulation, the bilayer composites presented a good conductivity which could be greatly optimized by thinning the cTPU layer. The bilayer composites also possessed balanced mechanical properties and showed excellent absorption-dominated electromagnetic interference shielding effectiveness. This work offers guidance for tailoring the performance of conductive polymer composites.