Mechanical, wear, water absorption and thermal behavior of rice straw carbon nanomaterial and pineapple fiber epoxy composites

This research investigates the development of high-performance epoxy composites reinforced with pineapple fibers and rice straw-derived carbon nanomaterial, targeting enhancements in mechanical strength, tribological behavior, thermal stability, and moisture resistance. Composites were fabricated via the hand lay-up technique, ensuring uniform fiber alignment and optimal carbon nanomaterial dispersion within the matrix. Among the formulations studied, specimen A14 (57 vol. % epoxy, 40 vol. % pineapple fiber, 3 vol. % carbon nanomaterial) exhibited superior mechanical properties, achieving a tensile strength of 166 MPa and flexural strength of 217.8 MPa, attributed to effective fiber-matrix interfacial bonding and crack-bridging by carbon nanomaterial. Conversely, specimen A15 (55 vol. % epoxy, 40 vol. % pineapple fiber, 5 vol. % carbon nanomaterial) demonstrated optimal functional properties, with the lowest specific wear rate of 0.0067 mm 3 /Nm and coefficient of friction of 0.21, due to the formation of a lubricated protective film from carbon nanomaterial accumulation. Furthermore, A15 achieved the lowest thermal conductivity of 93 W/mK, signifying enhanced thermal resistance, while recording maximum water absorption of 0.042%, primarily due to carbon nanomaterial agglomeration and the intrinsic hydrophilicity of natural fibers. SEM analysis revealed critical microstructural features across the specimens: A11 exhibited a smooth, brittle matrix; A12 showed distinct fiber fracture zones confirming energy dissipation; A13 and A14 evidenced strong matrix-fiber interlocks; and A15 displayed visible carbon nanomaterial clusters that acted as thermal barriers and wear-resistant zones, albeit introducing localized stress concentration. Overall, this study highlights the synergistic integration of bio-based fibers and nanoscale carbon additives to engineer lightweight, structurally robust, and multifunctional composites, paving the way for their utilization in automotive interiors, lightweight panels, and sustainable engineering components.