Quantitative correlation framework for dual-nanofiller reinforcement in Alumina/Graphene hybrid nanoadhesives via Pearson correlation matrix and heatmap analysis: Effects on mechanical and thermomechanical properties

This study aims to investigate the effect of Alumina/Graphene hybrid nanoreinforcement on the thermomechanical and mechanical performance of epoxy adhesives. The research addresses how dual-nanofiller interactions influence adhesive joining properties in aluminium alloy bonding. Hybrid nanoadhesives containing 1.0 wt% total filler with Alumina-to-Graphene ratios of 10:0, 7:3, 5:5, 3:7, and 0:10 were incorporated into a two-component epoxy adhesive system. Pearson correlation matrix and heatmap analyses were employed to quantitatively evaluate the relationships between key parameters with thermomechanical properties and joint strength. The results show that joining specimen with 7:3 Alumina-to-Graphene ratio exhibited the highest shear strength improvement of up to 62.6% compared with joining specimen with pristine adhesive, while relative to single nanofiller systems (10:0 and 0:10), enhancements of approximately 70.5% and 115.4% were obtained. It is concluded that the mechanical and thermomechanical performance of hybrid nanoadhesives are governed by the relative proportion of each constituent, as represented through the Pearson correlation matrix and heatmap analyses. The novelty of this study lies in extending a previously established Pearson correlation framework from single-phase to hybrid nanoadhesive systems, to capture dual-nanofiller interactions and competing mechanisms governing the overall mechanical and thermomechanical behavior of epoxy adhesives.