Effect of Pat/Agave/Coir-Dust Reinforcement on the Mechanical and Moisture Properties of Epoxy Composites

Abstract

Epoxy composites were reinforced with alkali (NaOH)–treated pat (jute) fibers, untreated agave fibers, and coir dust to improve mechanical and moisture resistance properties. Alkali treatment was applied to the pat fibers. Ten formulations (PA1–PA10) were fabricated by varying fiber proportions and evaluated for tensile, flexural, impact, hardness, interlaminar shear strength (ILSS), density, water absorption, and thickness swelling. Mechanical performance strongly depended on fiber composition and interfacial bonding. Tensile strength increased from 22 MPa (neat epoxy, PA10) to 44 MPa (PA3), while flexural strength ranged from 25 to 52 MPa, with PA3 showing superior performance. The highest impact strength (0.40 J), hardness (84 Shore D), and ILSS (9 MPa) were also observed for PA3, indicating efficient stress transfer. Moisture analysis showed minimum water absorption (10%) and thickness swelling (2.3%) for PA3. Density ranged between 1.20 and 1.36 g/cm³, suggesting that performance was governed mainly by interfacial interaction. Overall, PA3 (15% treated pat and 15% agave fiber) demonstrated the best balance of strength and environmental resistance. That formulation demonstrated the most balanced combination of mechanical strength, interlaminar integrity, and environmental resistance, highlighting the effectiveness of fiber reinforcement with coir dust for green epoxy composites.