Ionic Liquid‐Modified Multi‐Walled Carbon Nanotube/Styrene Butadiene Rubber Composites for Potential Strain Sensor Applications

Ionic liquid (IL) 1‐ethyl‐3methylimidazolium tetrafluoroborate‐modified multi‐walled carbon nanotube (MWCNT) was prepared by liquid phase roller milling. IL‐MWCNT/styrene‐butadiene rubber (SBR) composites were prepared by mixing IL‐MWCNT with SBR using a mechanical blending method. The infrared characteristics, vulcanization properties, mechanical properties, micro‐morphology, and electrical properties of IL‐MWCNT/SBR were investigated. The results showed that the MWCNT was physically encapsulated with IL. The addition of IL‐MWCNT accelerated the vulcanization of the composites. The best mechanical properties of IL/SBR were obtained at the IL content of 3 phr, and a sudden change in the electrical conductivity of the composites was observed at the content of 10 phr. The tensile strength and elongation at break of the composites with the addition of 10 phr of IL‐MWCNT reached the maximum at the MWCNT‐IL ratio of 1:1, and the sudden change in the electrical conductivity was observed. When the ratio of MWCNT to IL increases to 1:3 and the MWCNT is added to 5 phr, the composite is transformed from an insulator to a semiconductor. Overall, IL‐modified MWCNT exhibited a synergistic effect on enhancing the conductivity of IL‐MWCNT/SBR composites. Furthermore, the IL‐MWCNT/SBR composites exhibit excellent resistance strain characteristics across a wide range of strain rates, suggesting their significant potential for the fabrication of strain sensors.