Mechanical, thermal and physical properties of cellulose nanocrystal and graphene nanoplatelet as hybrid nanofillers for unsaturated polyester-kenaf core fiber bio-composites

The kenaf core fiber (KCF) was explored by incorporating it into unsaturated polyester (UPE) using the hand lay-up technique and fabricated using compression moulding. The study aims to maintain environmental sustainability and pursue lightweight properties by utilizing KC for automotive component applications since it has good mechanical properties, low cost, and, importantly, abundantly available. The hybridization technique was applied by incorporating 3 wt.% comprising cellulose nanocrystal (CNC) and graphene nanoplatelet (GNP) to increase the performance of UPE-KC bio-composite. The samples were characterized through tensile and flexural tests for mechanical analysis, thermogravimetric (TGA) and differential scanning calorimetry (DSC) representing thermal properties while water absorption for physical analysis. Particle size analysis (PSA) to measure the size of reinforcement materials, scanning electron microscope (SEM) to illustrate the micrograph of a fracture surface and Fourier transform infrared-Attenuated total reflection spectroscopy (FTIR-ATR) for chemical composition analysis also were applied to support the result. For PSA, the average size of KCF (838.8 um) was obtained, while the z-average of CNC and GNP was observed at 658.1 nm and 3655 nm, respectively. The hybrid nanofillers improve the flexural strength and modulus up to 48.2% (UKC1.5G1.5) and 84.21% (UKC0.52.5), respectively, compared to the UK. Overall mechanical properties were supported by the morphology observed UKCO.5G2.5 and UKC1G2 also show remarkable improvement in thermal stability with high ash residue by 42.1% and Tmax by 9.2 °C increment, respectively. Even so, Tg shows non-obvious changes upon adding reinforcement materials and nanofillers. UKC1G2 enhanced physical barrier up to 41.22% compared to the UK FTIR-ATR shows no changes in chemical structure upon the inclusion of nanofillers. Altogether, KCF is a potential material as reinforcement material while 3 wt.% nanofillers CNC and GNP contribute even better performance, mainly for UKC1G2.