Effect of Fe3O4 nanoparticles on magneto-responsive shape memory behavior of polyurethane-carbon nanotube nanocomposites

Magnetically-sensitive shape memory materials have attracted significant attention during recent decades, especially in biomedical applications, due to the noncontact triggering nature of their process. In the current study, Fe3O4 ceramic nanoparticles were deposited on the carbon nanotubes surface by an in situ chemical co-precipitation method in an alkaline solution. Then, the effect of incorporating these ceramic nanoparticles on the magnetic shape memory behavior of polyurethane-carbon nanotube nanocomposites has been studied up to 10wt% CNTs/Fe3O4. Other mechanical, thermal, and morphological tests were also performed on the fabricated nanocomposites, such as tensile, TGA, DTGA, DMTA, SEM, and TEM. A new model was finally obtained on the shape memory behavior of this composite. The obtained results showed that the magnetic hysteresis loops of PU-5%(CNTs/Fe3O4) and PU-10%(CNTs/Fe3O4) samples exhibited ferrimagnetism with the saturation magnetization of 2.9 and 4.6 emu.g(-1) with respect to nonmagnetic polyurethane property and the best magnetic shape recovery result was obtained for PU-10%(CNTs/Fe3O4) nanocomposite. Finally, recovery stress was measured to be increased by 111% with the incorporation of CNTs/Fe3O4, and a modified Halpin-Tsai equation was derived with the correction factor of K = exp(-2.079-89.5V(f)) to predict recovery stress of PU-CNTs/Fe3O4 nanocomposites.