Physical properties and shape memory behavior of thermoplastic polyurethane/poly(ethylene-<Emphasis Type="Italic">alt</Emphasis>-maleic anhydride) blends and graphene nanoplatelet composite

A new thermoplastic polyurethane (TPU) was prepared from polylactide-b-poly(ethylene glycol)-b-polylactide (soft segment) and 2,4-toluene diisocyanate (hard segment). Then, TPU in various proportions (i.e., 50, 70, and 90 wt%) was blended with poly(ethylene-alt-maleic anhydride) (PEMA) to form samples coded as TPU/PEMA50, TPU/PEMA70, and TPU/PEMA90. The TPU and PEMA blend at ratio of 50:50 was reinforced by various graphene nanoplatelets (GNPs) contents. Three novel strategies were opted in this research, including design of novel thermoplastic polyurethane, blend of TPU with poly(ethylene-alt-maleic anhydride), and fabrication of graphene nanoplatelet-based nanocomposites. Hydrogen bonding between blend component and GNPs directed the formation of regular nanostructure. Consequently, unique self-assembled flower-shaped morphology was observed in blends as well as hybrid materials using the scanning electron microscopy technique. Physical interlinking between blend components and nanofiller was also responsible for rise in tensile modulus (39.3 MPa) and Young’s modulus (4.04 GPa) of the TPU/PEMA/GNP 5 hybrid compared with the neat blend. The crystallization property was studied by the X-ray diffraction analysis and differential scanning calorimetry. The melting temperature of about 70 °C was preferred for the shape recovery studies. The results from heat-induced shape recovery were compared with those of electroactive shape memory effects. Electrical conductivity was increased to 0.18 S cm^?1 using 5 wt% GNP nanofiller, which was dependent on the applied temperature, as well. The original shape of TPU/PEMA/GNP 5 sample was almost 95 % recovered using heat-induced shape memory effect, while 98 % recovery was observed in an electric field of 40 V. Electroactive shape memory results were found to be better than those induced by heat stimulation effect.