Tensile performance and carbon intensity of natural fiber–reinforced polymer composites using bio-based epoxy resins

Growing concerns over carbon emissions have accelerated the development of sustainable composite materials that balance mechanical performance with reduced environmental impact. This study investigates natural fiber–reinforced polymer (NFRP) composites incorporating jute and sisal fibers with bio-based and conventional epoxy resin systems, with emphasis on tensile behavior and material efficiency. The effects of fiber type, resin system, and fiber volume fraction on tensile performance are systematically examined. Bio-based epoxy resin and synthetic epoxy resin are employed as matrix materials, while carbon fiber–reinforced polymer composites are included as benchmark references. The results indicate that optimal tensile performance is achieved at fiber volume fractions of 30–40% for NFRP composites and 40–50% for carbon fiber composites, regardless of the resin system. Excessively high fiber contents result in inadequate resin infiltration and reduced load transfer efficiency, whereas low fiber contents increase resin content and promote brittle failure. Jute fiber composites exhibit 12.4–34.5% higher tensile strength than sisal fiber composites, attributed to more effective fiber–matrix interactions. The use of bio-based epoxy resin enhances tensile strength and Young's modulus by up to 30% and 73.3%, respectively, compared with synthetic epoxy resin, while simultaneously reducing carbon intensity and improving cost efficiency. Overall, the results indicate that combining bio-based epoxy resins with natural fibers can produce polymer composites with competitive mechanical performance and improved carbon efficiency.