| Recently, a new method for the production of high-performance carbon fibers from mesophase pitch has been developed. A key bottleneck in this process involves the drying of heavy aromatic solvents from the pitch fibers before they are carbonized into the final product. Chapter 1 is the first study of the transport of these solvents in mesophase pitch. In this work, Convective Gravimetric Sorption, a new experimental technique, was developed that provides the flexibility needed to conduct this study. This technique was used to investigate the drying of a commercial spinning solvent, phenanthrene, and pyrene from pitch fibers, which were found to retain a residual amount of each solvent.; The work with a smaller solvent in Chapter 1 is extended in Chapter 2 as the diffusion and solubility of xylene (the common mixture of isomers) in the mesophase pitch fibers was measured with Convective Gravimetric Sorption.; In Chapter 3, the development of the Static Sorption Capsule is presented as an inexpensive and simple method for obtaining high pressure equilibria data in polymers and other sorbents. This technique involves measuring the total weight of a vessel containing the sorbent material pressurized with a vapor, assessing the amount of vapor in the headspace of the vessel with an appropriate equation of state, and evaluating the total amount of vapor in (on) the sorbent material by the difference.; The use of the Static Sorption Capsule technique has been further developed to measure the diffusivity of a gas in a polymer as well as the solubility.; Detailed in Chapter 5 is the development of a vapor-liquid equilibria model, using the Panayiotou and Vera equation of state, for poly(vinyl alcohol - vinyl acetate) copolymer with water, methanol, and methyl acetate. The homopolymer-solvent vapor-liquid equilibria data for each system are correlated with the Panayiotou-Vera equation of state. Mixing rules are proposed for the resulting pure-component and binary parameters to predict the vapor-liquid equilibria of each solvent with the copolymer.; Chapter 6 describes the creation of a user-friendly interface though Microsoft Excel for a finite difference diffusion model. The user interface allows a researcher or student who has not invested a great deal of time in the programming of numerical methods to model simple diffusion problems. (Abstract shortened by UMI.)... |
