Shape memory polymer carbon nanocomposites based on carbon nanopaper

Shape-memory polymers (SMP) composites have attracted significant attention from both industrial and academic researchers due to their useful and fascinating functionality. Generally, SMP can be actuated by heat, electricity, water and chemicals. A large amount of work has been done on the shape recovery of shape memory polymers blended with conductive filler triggered by electrical resistive heating. However, the conductive filler will dramatically undermine the shape memory behavior and there is no effective way to increase the conductivity without compromise on the shape memory behavior. In this work, carbon nanofiber (CNF) paper and bucky paper were introduced to actuate shape memory polymer, respectively. The shape recovery of polymer was carried out by electrical resistive heating generated by CNF paper and bucky paper which were attached to the surface of the SMP composites. Also, both of them possess excellent heat conductive properties which can serve as a conductive layer to transmit heat through the polymer. It was found that using this kind of structure the recoverability approximated to 100%. In addition, the geometry position in the composites of both types of paper was optimized to acquire the most efficient heat transfer rate from the paper to the SMP. After that, the structures of both CNF paper and bucky paper have been characterized by scanning electronic microscopy. Also, the electrical volume resistivity of the nanocomposite incorporated with different volume fractions of carbon nanofiber paper was measured by four-point probe method. The shape recovery process of the composites driven by resistive heating was recorded. The thermo-mechanical properties of the nanocomposites with respect to various volume fractions of carbon nanofiber paper were analyzed by dynamic mechanical analysis (DMA).