Thermo-electro-mechanical and Rheological Properties of Rubber Composites Filled with sp²-Hybridized Different Carbon Fillers

Rubber composites (RC) with enhanced thermo-electric properties are widely used in applications such as in flexible electrodes and solid tyres. In this work, the effect of carbon black (CB), multiwall carbon nano tubes (MWCNT) and natural graphite on thermal, electrical, mechanical and rheological properties of RC was studied. In all these fillers, carbon mainly has sp² hybridization. When the MWCNT loading was increased from 5 to 60 phr, the electrical conductivity of RC increased by four orders of magnitude. At 60 phr MWCNT loading showed five orders of magnitude higher electrical conductivity than CB added sample. The graphite loaded RCs were nonconductive. Hardness, elastic modulus, tensile and tearing strengths increased gradually with the increase of filler loadings. The variation of modulus of graphite-loaded samples was subtle. Interestingly addition of graphite showed higher elongation at break than that of pristine rubber. Viscoelastic characteristics showed that MWCNT added samples have least time and graphite added samples have highest time for curing compared to CB loaded samples. Although carbon-based fillers responsible for a significant improvement in their overall properties type of filler controls the extent to which the property changed.