Hybrid Bio-Composites Reinforced with Kenaf and Snake Grass Fibers and Neem Gum: Synergistic Effects and Role of Fiber Aspect Ratio

Abstract

The influence of neem gum powder (NGP) was evaluated relative to the mechanical, physical, and morphological properties of hybrid epoxy composites reinforced with varying ratios of kenaf and snake grass fibers. Six composite samples (KS1 to KS6) were fabricated with a constant epoxy content of 60 wt%. KS1 to KS5 incorporated 10 wt% NGP, while KS6 served as the control sample without gum. The results revealed a substantial improvement in mechanical performance with the inclusion of gum. The KS4 composite, containing 20% kenaf and 10% snake grass fiber, exhibited the highest tensile strength (59 MPa), flexural strength (82 MPa), inter-laminar shear strength (11.8 MPa), hardness (85.5 Shore D), and impact strength (5.23 J), along with the lowest water absorption (27%). In contrast, KS6 showed significantly lower values in all these properties, confirming the reinforcing effect of NGP. Scanning electron microscopic analysis of fractured surfaces revealed enhanced fiber-matrix adhesion in gum-containing composites, with fewer voids, reduced fiber pull-out, and minimal crack propagation, validating the mechanical test results. These findings demonstrated that the synergistic effect of hybrid fibers and gum significantly improved overall performance, making these composites promising for structural and eco-friendly applications.