High-strength, high-dissipation carbon nanotube nanocomposites

The interfacial sliding motion of carbon nanotubes (CNTs) within a polymeric hosting matrix gives rise to energy dissipation. By tuning the interfacial shear strength (ISS) of the CNT-matrix interface, the dissipation can take place within tunable ranges of strain amplitudes. This is the basis for conceiving new multilayered carbon nanotube nanocomposites in which different layers with tunable ISS can lead to a concurrent optimization of strength and dissipation, often seen as two conflicting targets. Such optimization is tackled by a novel meso-mechanical nonlinear inelastic model proven to effectively predict the damping capacity of CNT nanocomposites. The proposed elastoplastic, rate-independent, constitutive theory is based on the mean-field homogenization method which combines the Eshelby equivalent inclusion method, the Mori-Tanaka homogenization, and the concept of inhomogeneous inclusions with inelastic eigenstrains introduced to describe the inelastic stick-slip. Since the ISS parameter plays a key role in the nanocomposite strength and dissipation, the current work seeks to improve the strength and damping properties by suitable interfacial CNT-matrix functionalization. Variations of the ISS parameter can be achieved by a functionalization that affects the chemical bonds between CNTs and hosting matrix. A set of experimental tests - including DMA analysis, calorimetry and spectroscopy - aims to evaluate the influence of the ISS parameter, together with other constitutive parameters, on the nanocomposite strength and damping capacity.