Synergy studies on polyurethane–carbon black, multi-walled carbon nanotube-based heterogeneous electroactive shape memory nanocomposite system

This paper describes a multi-filler synergy study that was carried out for multi-walled carbon nanotubes (MWCNTs) and carbon black (CB) filler systems in polyurethane (PU) resin, and the individual contributions of the fillers were evaluated. The hybrid nanocomposite was found resistant to ultraviolet radiation and exhibited a high glass transition temperature enabling it suitable for space applications. The contributions of individual fillers in the hybrid system were compared with the binary nanocomposites of respective fillers and the advantages of hybrid system are also highlighted. The synthesized hybrid polymer nanocomposite (PU + CB + MWCNT) was found to have superior thermal, electrical and mechanical properties even at a very low content of reinforcements and a percolation threshold of 5% CB and 0.15% MWCNT combination was also observed. Shape memory effect of the hybrid system was evaluated and compared with binary systems. A faster recovery time of 41 s was observed for a combination of 5% CB and 0.25% MWNT against 50 s for 25% CB alone upon thermal actuation. On electrical actuation, the hybrid nanocomposite system was observed to have a three-fold faster recovery compared to the binary systems of CB alone. The hybrid system proves to be a reliable choice for replacing an expensive single reinforcement system of MWCNTs.