Assessment of open cell bio-based flexible polyurethane composites on mechanical, thermal and electrical properties for futuristic applications: An Initiative towards net-zero carbon emissions

Abstract This study proposes a novel approach to enhance the sustainability of polyurethane foam (PUF) by using renewable castor oil as a partial substitute for petrochemical polyols. The research focuses on developing an organic, low-density PUF reinforced with graphite nanoparticles (GNP), bamboo charcoal (BC), and zirconium oxide (ZrO2) nanoparticles. These reinforcements are incorporated using an absorption and hydrothermal reduction (AHR) technique. The resulting composite material is then evaluated for its multifunctional attributes, including density, tensile strength, flammability, and dielectric constant. The experimental results demonstrate significant improvements in the mechanical properties of the bio-based PUF, with the tensile strength increasing from 80 to 114 KPa due to the addition of nanoparticles. Moreover, the flammability tests show that while the bio-based PUF without nanoparticles achieved a UL-94 flame rating of V-2, the nanoparticle-reinforced PUF achieved higher ratings of V-0 and V-1, indicating improved flame retardancy. Furthermore, the study systematically assesses the dielectric properties of the open-cell bio-foam, comparing experimental results with a statistical experimental design. Optimization using an RSM central composite design (CCD) reveals a composition of 0.5 wt.% GNP, 0.5 wt.% ZrO2, and 2.5 wt.% BC results in a high dielectric constant of 4.95, making it suitable for effective dielectric applications. Experimental confirmation and simulation using COMSOL Multiphysics validate the optimized parameters, with error percentages of 3.12% and 2.48%, respectively. Overall, these findings underscore the potential of the proposed material as a sustainable alternative to conventional materials, aligning it with the growing demand for environmentally conscious solutions.