Comparison of mechanical properties of graphene added fiber reinforced polymer composites produced by conventional direct mixing and spray method

Glass fiber materials are one of the fibers preferred in composite production. One of the most important disadvantages of such composites is that glass fiber cannot establish a strong bond with epoxy resin and the toughness of the materials produced is low. For this reason, nanoparticles are used to improve the strength of the material in the z-axis direction and the bond between fiber and epoxy. In this study, it was studied to improve the fiber-matrix interface behavior of composites and to increase composite toughness by adding 0.5% graphene to the material. Within the scope of the study, samples were produced by direct mixing method and spray method. Triton X-100 surfactant was used to ensure homogenous dispersion. Three Point Bending Test, Dynamic Mechanical Analysis (DMA) and Scanning Electron Microscopy (SEM) Analysis were performed to examine the mechanical and thermal properties of the produced samples. When the test results were analyzed, it was seen that the highest flexural strength of the materials was 432.29 MPa and the flexural modulus was 14.96 GPa in the Spray Method. Thus, with the addition of 0.5% graphene, the flexural strength of the material increased by 15.25% in the Spray Method compared to the reference sample. On the other hand, according to the DMA analysis results, it was observed that the reference sample had the highest Tg value and Storage Modulus. The highest Tg value was determined as 114.6°C. The sample produced by spray method has the highest loss modulus and the highest dumping factor. These results are directly related to the crosslink density value of the material. When the images obtained by SEM analysis were analyzed, agglomerated graphene nanoparticles were observed in the structure of the material produced by direct mixing method. It was observed that homogenous distribution was achieved in the materials produced using the spray method compared to the direct mixing method.