Mechanical and electrical behavior of rubber nanocomposites under static and cyclic strain

Rubber nanocomposites based on carbon nanotubes (CNT), graphitic nanofiller (GR), and their hybrid (CNT+GR) were studied under static and cyclic strain for robotics applications. Room temperature vulcanized (RTV) silicone rubber was used as a matrix for the nanocomposites, which were prepared by solution mixing. The specimens based on CNT show a better modulus of 1.77 MPa than GR (0.71 MPa) and CNT+GR hybrid (0.85 MPa) specimens. The resistance was 0.27 kΩ (CNT) and 30.48 kΩ (CNT+GR hybrid) at 10% strain and increased to 0.35 kΩ and 46.49 kΩ at 100% strain. During cyclic strain (30%) tests, the CNT-based specimen shows larger hysteresis losses (slope m = -0.179) as dissipated heat than the GR (m = −0.032) and CNT+GR hybrid (m = -0.096) specimens. The specimens were tested as electrode materials in an actuator, and higher displacements of 1.992 mm (CNT), 1.489 mm (CNT+GR hybrid), and 0.075 mm (GR) were achieved at 10 kV (3 phr). Such improvements could be useful in intelligent objects as artificial muscles or electro-active locomotive parts.