Utilizing interfaces in carbon nanotube reinforced polymer composites for structural damping

Carbon nanotube reinforced polymer composites have been extensively researched [Shadler LS, Giannaris SC, Ajayan PM (1998) Appl Phys Lett 73: 3842; Ajayan PM, Shadler LS, Giannaris C, Rubio A (2000) Adv Mater 12: 750; Wagner HD, Lourie O, Feldman Y, Tenne R (1998) Appl Phys Lett 72: 188; Thostenson ET, Chou T-W (002) J Phys D: Appl Phys 35: L77] for their strength and stiffness properties. The interfaces between nanotubes and polymer matrix can play a critical role in nanocomposites for their mechanical properties, since the interfacial area is order of magnitude more than traditional composites. Unless the interface is carefully engineered, poor load transfer between individual nanotubes (in bundles) and between nanotubes and surrounding polymer chains may result in interfacial slippage [Shadler et al. (1998); Ajayan et al. (2000)] and consequently disappointing mechanical stiffness and strength. Interfacial slippage, while detrimental to high stiffness and strength, could result in very high mechanical damping, which is a hugely important attribute in many commercial applications. In this paper, we show that the mechanical damping is related to frictional energy dissipation during interfacial sliding at the extremely many nanotube-polymer interfaces, and characterize the impact of activation of the frictional sliding on damping behavior.