Effects of Graphene Oxide Thin Films and Nanocomposite Coatings on Flame Retardancy and Thermal Stability of Aircraft Composites: A Comparative Study

A polymer matrix system of thermoset fiber-reinforced composites helps protect its high modulus and strength fibers from an adverse environment and transfers the load to the reinforced fibers. However, when subjected to a high temperature that exceeds its postcuring-stage temperature, the polymeric matrix will decompose or be charred. To address this issue, various techniques have been developed to improve the flame-retardant property of the polymeric matrix. One of these techniques is to either delay ignition or release moisture to extinguish the flame by combining other chemicals or reactively modifying the epoxy resin. Graphene oxide (GO) nanofilms deposited on top of composite surfaces were compared with the test results of nanocomposite coatings of GO and nanoclay particles on composite surfaces. GO thin film applied to the surface of fiber-reinforced composites acts as a heat shield to quickly dissipate heat and eliminate local heat formation. Thermal tests, such as thermogravimetric analysis (TGA), 45-deg burn tests, vertical burn tests, and surface paint adhesion tests were accomplished. Average burn lengths and the average burn areas were reduced with nanoparticle inclusion to the nanoclay samples and graphene samples. TGA analysis indicated that the nanoclay inclusion samples, as well as the graphene inclusion samples, have a higher percentage weight loss than that of the base sample. GO inclusion samples were less affected than nanoclay inclusion samples during the vertical as well as 45-deg burn tests. In addition, there were no signs of damage to the GO thin film that was secondarily bonded to the surface of composite panels for the burn test.