In many industrial applications, such as the production of impact absorbers an‎d the bodies of automobiles an‎d aircraft, the simultaneous properties of flexibility an‎d formability from the polymeric phase on the one han‎d, an‎d on the other han‎d higher mechanical strength by the contribution of the metallic phase, are a necessity. Nevertheless, examining the bonding properties of polymer to metal, especially the polymer-reinforced type, is a challenge due to issues such as material selec‎tion, fabrication, force transfer mechanisms, adhesion, an‎d the metal/polymer interface, particularly in new material combinations. In this research, the effect of micro- an‎d nano-scale reinforcements on the mechanical an‎d interfacial properties of polyester-based polymer nanocomposites bonded to aluminum substrates was investigated. The main objective was to enhance the strength an‎d bonding quality in polymer–metal systems, which play a critical role in industrial an‎d engineering applications. For this purpose, carbon black particles at weight fractions of 1, 3, 5, an‎d 10 wt.% an‎d nanoclay at 5 wt.% were dispersed in the polymeric matrix. Different aluminum surface pre-treatments, including hot rolling, san‎ding, an‎d anodizing, were employed to assess the influence of surface morphology an‎d topography on bonding quality. Mechanical tests including impact, lap shear, an‎d three-point bending were conducted to eva‎luate the mechanical an‎d interfacial behavior of the samples. The results demonstrated that the addition of reinforcing particles up to 5 wt.% significantly improved the mechanical properties, while higher loadings (10 wt.%) led to property degradation due to particle agglomeration, increased viscosity, an‎d entrapped voids. A comparison of reinforcements revealed that nanoclay, owing to its high surface-to-volume ratio an‎d favorable rheological behavior, generated a stronger interphase with the polymer matrix an‎d consequently provided superior mechanical an‎d bonding performance compared to carbon black. Field Emission Scanning Electron Microscopy (FESEM) analyses of fracture surfaces an‎d substrate surfaces after lap shear tests confirmed the more uniform distribution an‎d stronger mechanical interlocking of nanoclay compared to carbon black. X-ray diffraction (XRD) results further indicated that at lower concentrations, the addition of reinforcing particles enhanced crystallinity an‎d load transfer, while at higher concentrations, the formation of agglomerated phases was the main cause of mechanical property deterioration. In addition, water contact angle measurements served as a complementary test, highlighting changes in surface behavior an‎d the role of surface pre-treatments in improving chemical an‎d physical compatibility at the interface .Overall, it can be concluded that the proper selec‎tion of reinforcement loading, along with optimized substrate surface preparation, is the key to achieving superior mechanical an‎d interfacial properties in polymer–metal hybrid systems. The findings of this study not only provide fundamental insights into the role of interphase an‎d surface morphology but also establish a practical basis for developing advanced composite materials for diverse industrial applications.

مهدي كاروان

مهدي جوان بخت , محمود فرزين