Microwave - Plasma based Thermal Treatment of Asphaltene - derived Carbon Fibres
Creators: name: Chandra, Sharath Krishna
Publisher: name: Graduate Studies
Year: 2024
Subjects: subject: Engineering--Mechanical

description: Asphaltene-based carbon fibres have emerged as a significant and sustainable alternative to conventional Polyacrylonitrile (PAN)-based carbon fibres, owing to their abundant availability, aromatic nature, and high carbon content. This thesis investigates the utilization of asphaltenes, extracted from bitumen in Alberta oilsands, as a valuable precursor for the manufacturing of carbon fibres. The precursor employed in commercial carbon fibre manufacturing accounts for approximately 51% of the total production cost. The utilization of asphaltene as a precursor offers the potential for cost reduction in carbon fibre production. With this reduced cost, carbon fibres, renowned for their exceptional mechanical properties such as high stiffness, remarkable tensile strength, chemical resistance, and capacity to withstand higher temperatures, can find applications across wide range of industries. Moreover, this cost reduction also contributes to the economic viability of converting industrial waste into valuable products. Conventional post-treatment processes in carbon fibre manufacturing, such as furnace stabilization and carbonization, play a crucial role in the production process, demanding considerable time and energy resources. Post-treatment alone, comprising 38% of the overall cost of carbon fibre production, significantly impacts the economic aspects of the manufacturing process. In this thesis, asphaltenes derived from Alberta oilsands are pretreated with solvents such as pentane and toluene to remove coke residues. Later, these asphaltenes are transformed into fibres through the process of melt spinning using a twin-screw extruder. An innovative approach involving microwave plasma thermal treatment, replacing conventional post-treatment methods, specifically carbonization, is then applied to convert these fibres into carbon fibres. The study of microwave plasma behaviour and its corresponding temperatures is successfully conducted through the use of Multiphysics Finite Element Analysis (FEA). An experimental optimization study involving the thermal treatment of stabilized fibres under varying power levels and treatment durations using microwave plasma has been conducted. The study successfully implemented microwave plasma techniques to achieve carbonization of asphaltene fibres, resulting in an increase in carbon content and the development of a well-ordered crystalline structure. The Element analysis revealed the dynamic changes in elemental composition, showcasing the effectiveness of microwave plasma in achieving carbonization. X-ray diffraction patterns and Raman spectroscopy provided valuable insights into the structural evolution, highlighting the unique impact of microwave plasma treatment on the development of a layered graphite-like structure and higher graphitic content. However, it is essential to acknowledge limitations, such as the observed surface damage and reduced tensile strength in microwave-plasma treated fibres, emphasizing the need for further optimization of parameters to maximize the benefits of this innovative approach. Overall, this research contributes valuable insights to the field of carbon fibre manufacturing, paving the way for more sustainable and economically feasible production processes with the utilization of asphaltene-based precursors and microwave plasma techniques.