Interface-derived solid-state viscoelasticity exhibited by nanostructured and microstructured materials containing carbons or ceramics

With 206 references, this paper reviews the field of interface-derived solid-state viscoelasticity that emerged in 1995 and grew with nanotechnology. Viscoelasticity is relevant to vibration and acoustic damping, as needed for cement-based composites, continuous fiber polymer-matrix composites, etc. This viscoelasticity mechanism involves interfacial friction and requires adequate interface area and feasibility of slight interfacial sliding. This mechanism is in contrast to the conventional viscoelasticity that involves bulk viscoelastic deformation, as in rubber. Compared to the conventional mechanism, this mechanism is attractive for the relative independence on temperature, the ability to withstand elevated temperatures, and the feasibility of simultaneously enhancing the loss tangent and stiffness. In monolithic materials, the interfaces are primarily the filler-matrix interface. Concerning multi-walled carbon nanotubes, the wall-wall interface also contributes. For providing interfaces, nanostructured/microstructured carbon or ceramic fillers (nanotubes/nanofibers, exfoliated graphite, ceramic particles, smectite clay, etc.) are effective, provided that their dispersion and interface design are adequate. For continuous fiber polymer-matrix composites, the filler volume fraction should be minimized. For non-monolithic materials (assemblies without a matrix, including fibers, nanotubes, exfoliated graphite and carbon black), which are potentially useful as the constrained layer in constrained-layer damping, the interfaces are primarily those between the structural units of the assembly.