Characterization of morphological, mechanical, and thermal response of highly-filled thermoplastic polyurethane hybrid nanocomposites reinforced with graphene and single-walled carbon nanotube

This research explores the influence of reinforcing Graphene (Gr) and Single-walled Carbon Nanotube (SWCNT) into Thermoplastic Polyurethane (TPU) on the thermo-mechanical behavior of Gr-SWCNT/TPU hybrid nanocomposites. Through the incorporation of SWCNTs along with Gr equally at higher nanofiller concentrations, a total of upto 10 wt.%, the thermal stability and mechanical stiffness of Gr-SWCNT/TPU hybrid nanocomposites are enhanced substantially. The dispersion of hybrid nano-reinforcements within the polymer matrix has been investigated using the microstructure images. Interactions between Gr-SWCNT hybrid nanofillers with TPU matrix material, construction of TPU linkages along with the elemental composition of pure TPU and Gr-SWCNT/TPU hybrid nanocomposites have been analyzed using different characterization techniques. Tensile testing demonstrates that TPU reinforced with 4 wt.% of each nanofiller. i.e., 4-4/92 hybrid nanocomposite, achieves 573.972% enhancement in elastic modulus compared to pure TPU. Further inclusion of carbon nanomaterials into TPU results in a reduction in tensile modulus. Enhanced thermal stability has been achieved through the incorporation of Gr-SWCNT hybrid nanofillers into TPU. 4-4/92 hybrid nanocomposite exhibits the most delayed decomposition (highest thermal stability) by 46 °C compared to that of TPU without any nano-reinforcements. Higher concentrations of nano-reinforcements beyond 4 wt.% Gr and 4 wt.% SWCNT in TPU are found to induce earlier thermal degradation. Such enhancements in thermal stability and mechanical stiffness are much better compared to those of TPU-based nanocomposites reinforced with single nanofillers. Further, the inclusion of hybrid nanomaterials within the polymer matrix reveals enhancements in melting temperature and reductions in glass transition temperature. The outcomes obtained in this study emphasize the potential of Gr-SWCNT hybrid nano-reinforcements to improve the thermo-mechanical performance of TPU for advanced applications.