Elastomeric evolution: A new look at carbon nanotube reinforced elastomers

Abstract

The use of elastomers in the rotating reference frame of helicopters is pivotal in the dissipation of vibration as a means of mitigating fatigue damage. Three of the largest cost drivers for elastomers from the perspective of design, maintenance and warranty are dampers, bearings, and hydraulic systems. One of the primary modes of failure of these components is degradation of elastomeric materials. To address these failures, elastomer compounds have been improved in conjunction with carbon nanotubes (CNTs) and structural health monitoring (SHM) technologies. Early work [1],[2]on embedding CNTs in elastomers focused on strength and electrical effects including modulus, conductivity and electro-magnetic interference (EMI) shielding properties. In some of the most recent work [3],[4] CNTs have been dispersed into viscous materials or spun into threads and used to measure strain in composite materials to functionalize CNTs embedded in elastomers. The CNTs used to form CNT thread originate in sheet form. This configuration or a variant of it would be ideal to use in hyperelastic materials such as elastomers due to its ability to undergo large deformations and maintain contact upon return to its original geometry. CNTs, when used as electrical sensors, also can enable material state awareness through SHM with the added benefits of improved strength properties and EMI shielding. The ability to sense strain using CNTs in the form of CNT thread is demonstrated on composites, the need to experimentally determine mechanical material properties of CNT elastomers is established through large variations among existing homogenization methods and the ability to detect damage in specific directions and monitor load with conductive elastomers is exhibited.