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 εF = 18%, but on contact with its casting solvent and subsequent drying, the sample can be regenerated to within εR = 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.