Optimization of cashew nut shell liquid and aluminum in epoxy resin: mechanical property analysis

Epoxy resins are widely used for structural and industrial applications due to their excellent mechanical and thermal properties, yet their inherent brittleness and dependence on non-renewable materials limit their broader utility. Addressing these limitations through sustainable additives is crucial for advancing eco-friendly, high-performance composites. This study explores the development of a hybrid polymer composite by incorporating CNSL and Al particles into epoxy resin to enhance toughness and strength. The research specifically aims to optimize the mechanical and thermal behavior of epoxy-based composites using renewable and metallic reinforcements. The methodology involved blending epoxy with 10–40 wt.% CNSL and 2.5 wt.% micro- or nano-sized aluminum particles, followed by molding, curing, and characterization using ASTM-based mechanical and thermal testing protocols. Results showed that the composite containing 30 wt.% CNSL and 2.5 wt.% nano-aluminum achieved a tensile strength of 50.5 MPa—over four times higher than pure epoxy—and demonstrated a 2.5-fold improvement in impact strength. Flexural modulus, hardness, and thermal stability also improved, while void content remained below 2%. The findings highlight the synergistic role of CNSL and nano-aluminum in enhancing both flexibility and structural integrity. This work presents a promising route toward sustainable, high-performance materials, with future studies recommended on interfacial optimization and long-term durability.