Investigation of Mechanical, Thermal Conductivity, and Wettability Properties of Castor Oil–Toughened Epoxy Composites Reinforced With Bagasse, Halfa Grass, and Coir Natural Fiber Particles

Abstract

This research examines the creation of sustainable castor oil–enhanced epoxy composites reinforced with three distinct natural fiber particles. Bagasse, coir, and halfa grass fibers were processed into particles and subjected to treatment with 5 wt% NaOH to enhance interfacial adhesion. Thirteen composite specimens were produced by the compression moulding process, integrating these fibers at different weight fractions (5–20 wt%), while utilizing castor oil as a bio‐based toughening agent within the epoxy matrix. The impact of fiber type and loading on mechanical, thermal and physical properties was methodically assessed. The findings demonstrate that the inclusion of fiber markedly enhanced tensile strength, elongation at break and impact resistance relative to unmodified epoxy–castor oil systems. All three fiber materials indicated favorable performance at 15 wt% loading, with coir fiber particles composites exhibiting the maximum tensile strength (42 MPa) and impact strength (3 kJ/m 2 ), although halfa grass had superior ductility. Thermal conductivity diminished to 0.36 W/m.K, signifying enhanced insulation, fluctuated with fiber amount. The contact angle and FT‐IR measurements validated improved surface and efficient fiber‐matrix interactions. The new composites exhibit significant potential for environmentally sustainable, semi‐structural applications.