Date of Thesis
Composites are a type of material that incorporates some amount of one material—termed the filler—into the bulk of another material—termed the matrix—to take advantage of the filler's properties without the product being solely comprised of filler material, which is typically more expensive than the matrix material. A filler material that has become extremely popular is carbon fiber. Due to their robust mechanical properties, carbon fibers are often incorporated into polymer matrices, resulting in a lightweight, ultra-strong material. These carbon-fiber reinforced polymer (CFRP) composites can be used in a range of products from aerospace to small consumer goods. As CFRPs become more popular, their end-of-use vectors must be assessed. Putting CFRP waste into landfills or burning results in total loss of the product and is detrimental to the environment. As such, recycling is preferred. Mechanical recycling methods grind up the waste CFRPs, resulting in pellets or powder that can be pressed into new products. By grinding the long-strand fibers into shorter pieces, much of their mechanical strength is lost, but these composites can still have enhanced properties over base-polymer. A recently-established processing technique called solid-state shear pulverization (SSSP) is applied to CFRPs to mechanically recycle them in an effective fashion. This thesis investigates SSSP as a method of not only breaking the carbon fibers apart, but exfoliating them into single sheets of graphene, and then dispersing the exfoliated carbon fibers. We propose that by exfoliating the fibers, SSSP can achieve higher levels of dispersion and incorporation of filler into matrix than comparable mechanical recycling methods. In doing so, where other mechanical methods would produce a macrocomposite, SSSP is creating a nanocomposite that is expected to have superior properties than macrocomposites of a similar filler due to the increased interaction between filler and matrix. This study demonstrates that, while SSSP is successful at exfoliating and dispersing carbon fibers into a polymer matrix, it does not have a significant impact on the mechanical properties of the resulting composite in comparison to another processing technique and clean polymer.
carbon fibers, exfoliation, solid-state shear pulverization, nanocomposite, recycling
Bachelor of Science in Chemical Engineering
Minnich, Keian Scott, "Exfoliation of Carbon Fibers into Nanocomposites via Solid-State Shear Pulverization" (2017). Honors Theses. 406.