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Mechanical properties of epoxy composites reinforced using carbon fibers film-type coated with carboxyl graphene using a novel and economical electrophoretic deposition technique




Carbon fiber, Electrophoretic Deposition, VARTM, Carboxyl Graphene, Strength


Carbon fiber reinforced polymer composites (CFRPs) show high specific strength and stiffness compared with other fiber reinforced polymer composites. However, these composites are most likely to fail at interface/interphase of fiber and epoxy owing to minimal interaction between the epoxy and the fiber due to the chemically inert nature of carbon fiber (CF) surface. Many CF surface modification techniques have been reported to increase the interfacial strength. Moreover, in some cases, incorporation of graphene fillers on CF surface is an effective way to enhance the interfacial adhesion strength between CF and epoxy. Electrophoretic deposition is an effective technique to deposit graphene nanofillers on CF fabric. In the current study, a novel combination of carboxyl functionalized graphene (G-COOH) and magnesium nitrate hexahydrate (Mg(NO3)2.6H2O) has been chosen for preparing colloidal solution to deposit G-COOH on carbon fibers. This colloidal solution facilitates the adsorption of more Mg+2 ions on the large number of active carboxyl functional groups present at the edges of G-COOH platelets and develops a positive charge on them. These platelets get deposited on cathodic electrode (i.e. carbon fiber fabric) with higher electrophoretic mobility during EPD. Hence, a uniform film-type layer of G-COOH platelets has been deposited with reduced EPD process parameters such as weight concentration of G-COOH platelets in suspension solution (g/L), deposition time and voltage compared to other studies. Surface morphology of G-COOH platelets deposition on carbon fiber fabric has been examined using scanning electron microscope (SEM). Surface characteristics of CFs has been studied using energy-dispersive X-ray spectroscopy (EDS) area mapping, FTIR and Raman spectroscopy. Four layers of pristine and G-COOH platelets deposited carbon fiber fabrics respectively have been used to manufacture the final composites through vacuum-assisted resin transfer molding (VARTM) technique. An increase in interphase thickness of G-COOH CF composite over pristine carbon fiber (PCF) composite was observed through carbon elemental EDS line scanning. G-COOH deposited CF composite showed enhancement in tensile strength and strain but reduction in flexural properties compared to PCF composites. This is due to higher prevalence of void formation in the G-COOH deposited composite.


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