Synergistic Effect of Chemical Treatment with Graphene Infused Hybrid Composites: A Study on Strength, Toughness, and Microstructure for Automotive Components

The development of lightweight and high-performance materials is vital for improving automotive efficiency and reducing environmental impact. This study investigates the synergistic influence of chemical treatment and graphene reinforcement on the mechanical and microstructural behavior of hybrid bio-composites fabricated using Syzygium cumini and Morinda tinctoria fibers. Hybrid composites were produced in varying resin-to-fiber ratios (65:35, 70:30, 75:25) with 1–2 wt.% graphene nanoplatelets uniformly dispersed in an epoxy matrix, and fibers subjected to alkaline treatment to enhance interfacial compatibility. Mechanical characterization revealed a substantial improvement in treated, graphene-modified composites, including a ~ 39% increase in tensile strength, a ~ 30% rise in flexural strength, and a ~ 27% enhancement in impact resistance compared to untreated counterparts. Water absorption decreased by up to 45%, while hardness values increased notably, reflecting improved surface integrity. SEM analysis confirmed superior interfacial adhesion, reduced voids, and uniform graphene dispersion, while FTIR, XRD, and TGA results verified enhanced structural order, chemical stability, and thermal resistance. The combined effects of graphene infusion and chemical treatment significantly elevate fiber – matrix bonding and overall composite performance. These findings establish the treated graphene-reinforced S. cumini/M. tinctoria hybrid composite as a promising lightweight material for structural automotive components, particularly bonnet applications.