Preparation Of Graphene Oxide Coated Glass Fiber Reinforced Composites

The graphene has the good conductivity and can be widely applied in the field of electromagnetic shielding.Light-weight and high-strength glass fiber is a good framework material.In this paper,the glass fiber-graphene/resin matrix composites were prepared by modifying the surface of the glass fiber using the graphene.The silane coupling agent and bovine serum albumin were used as coupling agents for surface modification of glass fiber by employing the electrostatic self-assembly method.The reductive agent was finally introduced for the reduction of graphene oxide at the surface of the glass fiber.The microstructures of graphene and graphene oxide,as well as their morphologies,phase structures,surface chemical bonds and molecular structures,were characterized by the technologies of scanning electron microscope(SEM),X-ray diffraction(XRD),Raman spectra,Fourier transform infrared spectroscopy(FT-IR).The glass surface treatment was evaluated by contact angle test and thermos gravimetric analysis(TGA).The mechanical properties and electromagnetic shielding effectiveness of the as-modified glass fiber reinforced resin matrix was characterized.The main conclusions are as follows:The oxygen-containing groups of graphene oxide mainly exist in the form of-OH,-COOH,-C-O,-C-O-C-,etc.,and the absorption peak intensity of the carboxyl group and the carbon oxygen bond was greatly reduced.The G peak of graphene oxide became wider,and a new D peak,indicative of the SP3 hybridization of carbon atoms,is detected,which indicates that the introduction of oxygen-containing groups had destroyed the SP2 hybrid π bond structure.After reduction,the ratio of ID/IG decreased,implying that some of the SP3 hybrid carbon atoms in the reduction process were restored to SP2 hybrid π bond structure.Compared with the conductivity of graphene oxide and graphene oxide,the conductivity of graphene oxide is much higher than that of graphene oxide.Hydrochloric acid solution and sodium hydroxide solution were used to hydroxylate the glass surface,and to reduce the glass and water contact angle.The optimal processing time for acid treatment was 70 min using 3 mol/L acid,and the contact angle was 21 o;while that for alkali treatment was 40 min using 8 mol/L alkali,and the contact angle was 16 o.Using 0.5wt.%-5.0wt.% coupling agent and a modification time of 10-50 min,the contact angle increased with the concentration and peaked at 68 o when the coupling agent mass fraction was less than 1%,and if the coupling agent mass fraction is more than 1%,the contact angle was not obviously changed.The optimum parameter for the treatment of coupling agent was 1.0wt.% concentration with a treatment time of 30 min.When the concentration of dispersed graphene oxide was 1%,the surface of the glass fiber coated with only rare and small layers of graphene oxide layers,and as a result,there are a large number of glass fiber surface exposed.When the concentration of dispersed graphene oxide increased up to 1.5wt.%,the modified graphene oxide covered the large majority of glass fiber with a good effect of fold.When the concentration of graphene oxide increased to 2.0wt.%,graphene oxide layers gathered together on the surface of glass fiber,and cannot achieve a uniform and stable effect.The optimal conditions for the glass fiber coated with graphene oxide dispersion are as follows: 1.5wt.% concentration,treatment time: 70 min.The mechanical properties of the resin matrix composites were greatly improved by the modification of the glass fiber.When the adding amount of glass fiber content was 30 wt.%,the tensile strength of 85.05 MPa is increased by 51.4% compared to the unreinforced resin material(56.16MPa),mainly due to the interface modification by graphene thus greatly improving the tensile strength of the composite.When the glass fiber content reached 20%,the shear strength of the composites reached the maximum value of 34 MPa.The electromagnetic shielding effectiveness of composite materials has increased with increasing amounts of glass fiber,and the shielding effectiveness of composite materials in 8.2GHz were 8.56 dB,12.2dB,13.8dB and 20.4dB,compared to 2.1dB(unreinforced).When the fiber content is 40 wt.%,the preparation of samples received the superior electromagnetic shielding of 21.7dB at 12.4GHz.The enhanced electromagnetic shielding effectiveness of the composites mainly originated from the increase in the internal absorption loss.