Synergistic effect of granite powder filler on mechanical and thermal properties of alkali-treated jute-epoxy hybrid composites

ABSTRACT This study reports the development of hybrid composites comprising alkali-treated jute fibers and granite powder filler dispersed in an epoxy matrix. Five composite formulations were fabricated via hand layup, maintaining a fixed jute content (20 wt.%) while varying granite powder from 0 to 20 wt.% in increments of 5 wt.%. Jute fibers underwent pretreatment with 5% NaOH solution to improve fiber-matrix adhesion. The key novelty lies in demonstrating a synergistic interaction between the fibrous reinforcement and particulate filler, yielding concurrent enhancements in mechanical and thermal performance. Furthermore, utilizing granite waste as a functional filler introduces an underexplored sustainable dimension in jute-based hybrid composites. Mechanical evaluation showed that tensile, flexural, and impact properties progressively increased with granite content up to 15 wt.%, beyond which they declined. The optimum composite (20 wt.% jute + 15 wt.% granite) achieved 154% higher tensile strength and 121% higher tensile modulus relative to the unfilled jute-epoxy composite. Density and void content analysis revealed reduced void fraction with increasing filler loading. Thermogravimetric analysis confirmed improved thermal stability for granite-filled composites, with degradation onset at 420 °C and residual mass of 39.24% at 850 °C. Scanning electron microscopy evidenced uniform filler dispersion, fewer voids, and strong interfacial bonding at optimal filler content. Water absorption tests indicated decreased moisture uptake as filler percentage increased. The successful integration of industrial waste granite powder and natural jute fibers offers an eco-friendly, sustainable composite suitable for automotive interior components as well as construction applications, while simultaneously addressing waste management challenges.