Mechanical characterization of epoxy - alumina composites: A study on tensile, flexural and shear properties

Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India.

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Published online: 2 March 2026

Abstract

This study investigates the mechanical performance of epoxy composites reinforced with varying weight percentages of aluminium oxide (Al₂O₃) nanoparticles. Composites were fabricated with 0%, 0.25%, 0.5%, 0.75%, and 1% Al₂O₃ by weight, and tested according to ASTM D638 (tensile), ASTM D790 (flexural), and ASTM E1876 (shear/dynamic) standards. The results revealed that the incorporation of Al₂O₃ significantly enhanced the tensile, flexural, and dynamic mechanical properties up to an optimal loading of 0.5 %, beyond which a gradual decline was observed. The maximum tensile strength (50.1 MPa) and flexural strength (96.18 MPa) were obtained at 0.5% Al₂O₃, along with an improvement in Young's modulus and shear modulus, indicating improved stiffness and load-bearing capacity. The enhancement is attributed to uniform nanoparticle dispersion within the epoxy matrix, which improved interfacial bonding and stress transfer. However, excessive filler loading led to agglomeration, reducing homogeneity and mechanical performance. Overall, the results confirm that 0.5 % Al₂O₃ provides the best balance of strength and stiffness for epoxy-based composite systems.