Assessing mechanical and fracture damage mitigation by polydopamine functionalized milled GO in epoxy nanocomposites

Fascinating features of 2D structured carbon nanomaterials, such as graphene oxide, have garnered significant interest due to their capacity to improve the mechanical strength and fracture toughness of epoxy nanocomposites. However, challenges still lie in improving their dispersibility within the polymer matrix and enhancing interfacial interactions. This paper investigates effective surface functionalization of ball-milled graphene oxide by using polydopamine. The process demonstrated improved dispersibility and stronger interfacial bonding with the epoxy matrix, which are crucial for fabricating high-performance nanocomposites. After surface functionalization of BGO with polydopamine, the resulting D-BGO was characterized, and the following results were obtained. The FESEM shows that D-BGO exhibited a rougher and more wrinkled texture, whereas AFM analysis confirmed sheet thicknesses of 0.94 nm for BGO and 2.57 nm for D-BGO. The hybrid epoxy nanocomposite reinforced with surface functionalized D-BGO3hrs@1% demonstrated significant improvement in tensile strength (∼45%), tensile strain (∼57.4%), and tensile modulus (∼58%) with respect to the control. Similarly, flexural properties such as FS, FSt, and FM of the D-BGO3hrs@1% nanocomposites were increased by ∼37%, ∼34%, and ∼42%, respectively, related to the neat epoxy composite. The fracture toughness and energy increased by 2.32 MPa·m1/2 (160.6%),1.36 kJ/m2 (423%), and surface indentation resistance by 38% compared to the control at the above filler wt.%. The enhanced fracture toughness is attributed to the superior dispersion of D-BGO3hrs, enabling strong interfacial bonding with the epoxy matrix. FESEM images show improved surface roughness, shear steps, crack branching, crack pinning, pull-out, and polymer chain bridging, all contributing to improved fracture toughness. Incorporation of 1 wt% D-BGO3hrs significantly improves fracture toughness and energy absorption. Highlighting their potential applications in the automobile sector, such as body panels, brake paddles, and in defense, including lightweight ballistic panels and armor.