Mechanical performance of highly compressible multi-walled carbon nanotube columns with hyperboloid geometries

Multi-walled carbon nanotube (MWCNT) columns are formed from the frit compression of a random distribution of MWCNTs in a casting solvent; its drying led to the formation of hyperboloid geometry. Uniaxial loading of MWNT columns mimics an open-cell foam behaviour and possesses an expansion rate in excess of 250 mm min^-1 and an elastic modulus of 10-12 MPa, thus superior to conventional low-density flexible foams. Successive compression-expansion cycling within the Hookean region reveals a hysteresis loop in the stress-strain curve that stabilises at a final value of ε_F = 18%, but on contact with its casting solvent and subsequent drying, the sample can be regenerated to within ε_R = 6% according to a memory effect and is repeatable in successive stress cycles and solvent regeneration. The system was modelled for the macroscopic stress-strain behaviour of the MWCNT column to reveal the contributions of linear dependence, elasticity-plasticity and elasticity-plasticity with hardening, revealing good agreement with the stress-strain data. MWCNT columns should prove useful as an energy adsorbing device.