Mechanical properties of nanocomposites reinforced by carbon nanotube sponges

Carbon nanotube (CNT) sponge exhibits unique porous and hierarchical structure that are beneficial to the design of ultralight and tough composites. In this study, CNT sponges (undoped and boron doped) reinforced polydimethylsiloxane (PDMS) composites were fabricated. Mechanical properties of the composite, including compressive modulus, rate-dependent modulus, stress relaxation behaviors, dynamic viscoelastic properties, and their dependency on temperature, were systematically investigated. A micromechanical model, Mori-Tanaka model, was validated to describe the mechanical behaviors of CNT sponge reinforced composites. By coupling with boron-doped CNT sponge, PDMS composites showed remarkable improvement of mechanical properties, including compressive modulus (70%), viscous modulus (243%) and damping capacity (50%). Such reinforcement effects can be controlled by the morphology of CNT sponges, as the boron-doped and undoped nanocomposites showed distinct viscoelastic behaviors. The results proved that CNT sponge reinforcement is a promising strategy to develop engineering composites with both outstanding mechanical stiffness and controllable viscoelastic performances.