Effect of Post-Cathodic EPD Acetone Washing of Carbon Fibres on the Mechanical Properties of Graphene Carboxyl Embedded CFRP Composites

Carbon fibre-reinforced polymer (CFRP) composites have evolved as one of the most reliable materials for critical structural applications. Electrophoretic deposition (EPD) is one among the most opted routes to carry out the surface modification of carbon fibre (CF). Methyl violet (MV) is used in the cathodic EPD technique to maintain stability of suspension and to impart positive charge to the nanofillers thereby facilitating the cathodic EPD. In the current research work, the authors have deposited graphene carboxyl (G–COOH) on CF surface via cathodic EPD route, and an attempt was made to analyse the impact of MV on the mechanical behaviour of the modified CFRP composite by carrying out flexural and short beam shear tests. The G–COOH/CFRP composite in which MV was removed with acetone washing has shown an improvement of 21.93% and 10.89% in interlaminar shear strength (ILSS) and flexural strength (FS), respectively, in comparison to neat CFRP composite. However, G–COOH/CFRP composite in which the MV was not washed has shown a decrement of 20.82% and 3.21% in ILSS and FS in comparison to neat CFRP composite, respectively. High-resolution transmission electron microscope was used to observe the morphology of graphene carboxyl, and scanning electron microscope was used to carry out fractography analysis to comprehend the failure mechanism and dominant failure mode. Fourier transform infrared spectroscopy analysis was carried out to understand the effect of methyl violet on the epoxy/nanofiller interface chemistry.