Optimization of Processing Parameters for Bio‐Based Epoxy Composites Reinforced With AP1 Green Ramie Fiber: Mechanical, Thermal, and Morphological Characterization

ABSTRACT This study reports the fabrication and optimization of a bio‐based composite comprising an epoxy resin matrix (E.G128) reinforced with AP1 ramie fibers, a native Vietnamese natural fiber. Response surface methodology (RSM) with a Box–Behnken design was used to evaluate the effects of fiber length, fiber content, and compression pressure on mechanical performance, and to determine optimal conditions: fiber length of 5 mm, compression pressure of 5 MPa, and fiber content of 30 wt%. The optimized composite achieved outstanding properties, including tensile strength of 237.08 MPa, flexural strength of 224.32 MPa, impact strength of 63.96 kJ/m ² , and elongation at break of 2.27%. SEM, FTIR, and TGA analyses confirmed uniform fiber distribution, strong interfacial bonding via hydroxyl–epoxy interactions, and significantly enhanced thermal stability over neat epoxy. The developed quadratic regression model exhibited high accuracy and predictive capability, with close agreement between experimental and predicted values. Compared with previously reported natural fiber‐reinforced composites, the E.G128/AP1.30 system offered superior mechanical and thermal performance. These results demonstrate the potential of AP1 ramie fibers for producing sustainable, eco‐friendly composites suitable for applications in construction, interior design, and lightweight structural components.