Nanocomposites and graphene oxide thin film coatings on the surface of fiber reinforced composites for enhanced flame retardancy
Le, Louie N.
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The polymer matrix system of thermoset fiber-reinforced composites helps protect the high modulus and strength fibers from the adverse environment and also transfer the load to reinforced fibers. However, when subjected to the high temperature, that exceeds its post curing stage temperature, the polymeric matrix will be decomposed or charred. This can result in degradation or failure of the entire composite structure. Because of this drawback many researchers have tried with different methodologies to improve the flame retardant property for epoxy resin matrix by reactive and additive methods. For instance, epoxy resin was reactively modified by incorporating other chemicals to delay ignition or to release moisture to extinguish the flame. Halogenated compounds and nanoparticles have also been additively dispersed into epoxy resin to form ash layers during combustion to resist the flame from outspreading. With the same intent to enhance flame retardancy for epoxy resin matrix (protecting the matrix system and reinforced fibers) this research incorporates nanoparticles, including nanoclay and graphene oxide, into the epoxy primer as coatings on composite surfaces. Another approach was to secondarily bond a thin film graphene oxide onto the surface of fiber reinforced composites to act as a heat shield. Thermal tests, such as, Thermogravimetric Analysis, 45 degree burn tests, vertical burn tests and Surface Paint Adhesion tests were done in accordance to guidelines of FAA Regulations, ASTM, SAE, and AMS specifications. The test results revealed significant improvements in composite flame retardancy by incorporating graphene oxide and graphene oxide thin film coatings. Graphene oxide inclusion samples were less affected than nanoclay inclusion samples during the vertical as well as 45 degree burn tests. In addition, there were no signs of damage to the graphene oxide thin film that was secondarily bonded to the surface of composite panel from the 45 degree burn test.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering