Structure-property relationship in silicone rubber nanocomposites reinforced with carbon nanomaterials for sensors and actuators

Abstract

A small amount of nanofillers can significantly improve the mechanical and electrical properties of nanocomposites, which have a wide range of applications such as sensing and actuation. In this work, rubber nanocomposites were prepared with 0-dimensional (0-D) carbon black (CB), 1-D carbon nanotube (CNT), 3-D graphitic nanofiller (GR), and room temperature vulcanizing (RTV) silicone rubber. The different structures of the CB, CNT, and GR nanofillers were characterized. In addition, the effects of the structures on the mechanical properties and electromechanical applications of the nanocomposites were experimentally demonstrated. At a filler loading of 6 phr, the elastic modulus was improved by 150, 350, and 130 % with the nanofillers of GR, CNT, and CB, respectively. We found that the CNT-based silicone rubber nanocomposite exhibited the highest tensile strength and the reinforcing effect compared to that of others. Based on the improved mechanical, electrical properties of RTV rubber by the nanofillers, the nanocomposites were successfully adopted for strain sensing and actuation applications. The CNT- and CB-based nanocomposites have been used as piezoresistive strain sensors with a gauge factor of 1.3 and 7.8, respectively. The stretchability of strain sensor is up to 80 and 100 % for CNT and CB nanocomposites, respectively, while both of them show high durability. In addition, the nanocomposites are used as an electrode for piezoelectric actuation, and the mechanical displacement was 2.5, 0.34 and 0.5 mm for CNT-, GR-, and CB-based nanocomposite, respectively, under identical actuation voltage of 12 kV. A series of experiments demonstrate the dependency of properties of nanocomposites on the structural characteristic of carbon nanofillers.