Mechanical, wear, and thermal properties of mercerized cattle hair fiber-aluminium particles hybrid reinforced epoxy-based composites for potential automotive application

Natural fiber reinforced polymer composites are increasingly explored as sustainable alternatives to conventional automotive materials, yet the potential of animal-based waste fibers, specifically those derived from livestock slaughter by-products, remains less explored relative to their plant-based counterparts. This study investigates the effect of alkaline mercerization and hybrid reinforcement loading on the mechanical, tribological, and thermal properties of cattle hair fiber and aluminium particle reinforced epoxy composites, targeting automotive interior and heat shielding applications. Cattle hair fibers were treated with 0.2 M NaOH at 105°C for 55 min, conditions selected to disrupt the keratin cuticle and improve wettability without degrading the protein backbone and composites were fabricated by hand lay-up at reinforcement weight fractions ranging from 3 to 15 wt%, maintaining equal proportions of fiber and particulate. FTIR spectroscopy confirmed mercerization through the emergence of sulfonate-related peaks associated with disulfide bond disruption, while retention of Amide I, II, and III bands verified the structural integrity of the keratin phase post treatment. SEM and EDX analyses confirmed co-dispersion of both reinforcements within the epoxy matrix, and XRD revealed the amorphous morphology of the cured thermoset system. Progressive reinforcement loading produced consistent improvements across tensile, impact, tribological, and thermal insulation properties. Peak tensile strength of 53.84 MPa and impact strength of 18.63 kJ/m² were recorded at 15 wt%, representing enhancements of 110% and 244% over the neat epoxy, respectively. Flexural strength and hardness were optimized at 12 wt% (24.57 MPa and 57 HS), beyond which reinforcement agglomeration became the microstructural influence. Wear resistance improved across all loading levels, with a 35.6% reduction in mass loss at 15 wt% relative to the control. Thermal conductivity declined from 88.25 mW/m·K for the neat epoxy to 36.94 mW/m·K at 15 wt%, a reduction driven by the insulating nature of the porous keratin structure and entrapped micro voids at the reinforcement matrix interface. These findings show that mercerized cattle hair fiber and aluminium particle hybrid epoxy composites represent a credible, low-cost, and environmentally responsible material candidate for non-structural and semi-structural automotive components, with relevance to interior panels, cabin insulation, and thermal barrier applications. Moisture durability and long-term service performance under realistic automotive conditions remain subjects for further investigation.