Effect of boron carbide filler on the mechanical properties of flax fiber reinforced epoxy composites

The epoxy hybrid nanocomposite is prepared with 15 wt% of flax fiber (FF) and 1-5wt% of boron carbide nanoparticle (B4C) through a compression moulding process. Before the fabrication, the FF surface is treated with a 5% concentration sodium hydroxide solution to enhance fiber quality and reduce moisture absorption. The impact of FF and B4C on the flexural, impact, and hardness properties of the composites is evaluated and compared with an epoxy/15wt% FF composite sample. The flexural, impact, and hardness of composite samples (epoxy/15wt% FF, epoxy/15wt% FF/1 wt% B4C, 3wt% B4C, and 5wt% B4C) show significant enhancement. For instance, the flexural and impact strength varies 48.5, 53.5, 58.6 & 65.6 MPa for flexural strength and 3.6, 4.1, 4.8 & 5.3 J/mm2 for impact strength. Similarly, the composite sample’s hardness demonstrates a remarkable improvement of 32.5, 35.6, 41.6, & 46.7 HV with increasing B4C content (0, 1, 3, & 5 wt%) in epoxy/15wt% FF. The epoxy hybrid nanocomposite comprising 15wt% HF and 5wt% B4C achieves the optimal values. The flexural and impact failure is analyzed using scanning electron microscopy, revealing interfacial debonding and matrix cracking failures. This composition is used in automotive cabinet applications.