Comparative multi-response optimization of mechanical properties in jute/flax-epoxy composites processed by hand layup and VARTM

Abstract Natural fiber-reinforced composites (NFRCs) are gaining increasing attention as sustainable alternatives to synthetic composites in lightweight structural and biomedical applications. This study presents a comparative evaluation of jute/flax-epoxy hybrid composites fabricated using two manufacturing methods: conventional hand layup and vacuum-assisted resin transfer molding (VARTM). Mechanical properties, including tensile strength, flexural strength, impact strength, and hardness, along with physical properties such as density and water absorption, were systematically analyzed. The results revealed that VARTM-fabricated composites exhibited significantly superior mechanical performance compared to hand layup specimens. Tensile and flexural strengths were improved by approximately 43.3% and 36.1%, respectively, while impact strength increased by 34.7%. The enhanced properties were attributed to improved fiber–matrix adhesion, reduced void content, and uniform resin distribution in the VARTM process. Conversely, hand layup composites demonstrated higher water absorption due to increased porosity. Overall, VARTM emerged as a superior fabrication method for high-performance applications, whereas hand layup remains a cost-effective choice for less demanding uses. Importantly, the findings highlight the potential of jute/flax-epoxy composites in biomedical applications, particularly in the development of lightweight and sustainable prosthetic devices.