Investigation on mechanical properties of crotalaria juncea fibre with naturally extracted cellulose filler reinforced epoxy resin

Abstract This study investigates the development and mechanical characterization of epoxy composites reinforced with Crotalaria juncea (sunn hemp) fibres and naturally extracted cellulose filler. Physical properties including density, water absorption, and thickness swelling were also evaluated to gauge suitability for medium-density fiberboard (MDF) applications. Composite laminates were fabricated using different fibre volume fractions (20, 25, 30, and 35 vol. %) and cellulose filler contents (5, 7.5, and 10 vol. %) to evaluate their influence on mechanical performance. Tensile, flexural, impact, and hardness properties were examined in accordance with ASTM standards. The tensile strength of the composites varied from 18.12 MPa to 39.07 MPa, while flexural strength ranged between 29.52 MPa and 74.56 MPa. Impact energy absorption values were found to be in the range of 1.1 J to 2.7 J, and Shore D hardness values ranged from 75.63 to 89.18. The composite containing 30 vol. % fibre and 7.5 vol. % cellulose filler exhibited the most favorable mechanical performance among the investigated compositions. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) analyses were carried out to study chemical interactions and crystalline characteristics, while Scanning Electron Microscopy (SEM) was used to examine fracture surface morphology. Tests of thermal stability (TGA) were performed to assess decomposition behavior. The results demonstrate that appropriate cellulose filler incorporation improves fibre–matrix interaction and mechanical behaviour. The developed composites show potential for interior and structural applications where sustainable materials are required.