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

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 (0.58 wt%) was obtained in PANI/FMWCNT/TPU composites. It displayed a conductivity of 28.6 S/m and EMI shielding efficiency (SE) of 31.35 dB in X band region at 8% filler concentration. For FMWCNT/TPU composites, the values were 1.52 S/m and 19.65 dB 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.