Electro-Induced Shape Memory Nanocomposite Containing Conductive Carbon Nanotubes

We fabricated a chemically cross-linked material that exhibits a shape memory effect and characterized its mechanical and electrical properties. The material consists of a blend of a poly(styrene-b-butadiene-b-styrene) triblock copolymer (SBS) and linear low density polyethylene (LLDPE) and different amounts of multi-walled carbon nanotubes (MWNTs). The melting temperature of the composite containing the MWNTs is lower than for pure SMP according to our Differential Scanning Calorimetry (DSC) results. Scanning Electron Microscope (SEM) reveals that the particulate additives are dispersed homogeneously within the SBS/LLDPE blend and create an interconnected conductive network. The Young modulus of the SMP composite with 6 wt.% MWNTs content increases by 124.3% and the tensile strength by 123.9% at room temperature, compared to pure SMP. The Four-point Van Pauw method was used to measure the electrical conductivity of the composites. A volume resistivity of 1.131 Omega/cm is measured for the 6 wt.% MWNTs composite. The electroactive shape memory test indicates that for a MWNTs content over 3.0 wt.%, full recovery can be observed after tens of seconds. The shape recovery speed increases with both increasing MWNTs content and voltage. The shape recovery rate decreases slightly with the number of recovery cycles.