Electrical, thermal, mechanical and electromagnetic interference shielding properties of PANI/FMWCNT/TPU composites

•Conductive TPU composite using Polyaniline coated FMWCNT was prepared by in-situ polymerization assisted by sonication.•Electrical, mechanical, thermal and EMI shielding properties of the composite films are significantly higher.•The percolation threshold was achieved at very low filler loading of 0.58wt %.•A high conductivity of 28.6S/m and a shielding efficiency of 31.35dB were achieved. Thermoplastic polyurethane (TPU) composites based on polyaniline (PANI) and functionalised multiwalled carbon nanotubes (FMWCNT) were prepared by in-situ polymerisation of aniline in TPU solution assisted by ultra sonication (PANI/FMWCNT/TPU). Composites without polyaniline were also prepared by the same method (FMWCNT/TPU). Field emission scanning electron microscopy and transmission electron microscopy images of these composites showed good dispersion in the case of PANI/FMWCNT/TPU composites. The electrical and electromagnetic interference (EMI) shielding properties of the prepared composites were studied as a function of weight percentage of FMWCNTs. In-situ polymerisation reduced the aggregation of FMWCNTs and improved its dispersion as well as interfacial interaction with TPU matrix. Thus a low percolation threshold (0.58wt%) was obtained in PANI/FMWCNT/TPU composites. It displayed a conductivity of 28.6S/m and EMI shielding efficiency (SE) of 31.35dB in X band region at 8% filler concentration. For FMWCNT/TPU composites, the values were 1.52S/m and 19.65dB respectively. Absorption, rather than reflection, was found to be the major shielding mechanism. Enhanced thermal and mechanical properties of the currently prepared composites were confirmed by TGA, DMA and tensile analysis.