Carbon fiber is one of the leading materials for high strength and modulus, and light weight applications. Improvements in carbon fiber properties are directly dependent on all aspects of manufacture, especially the process of stabilization. Therefore, it is the goal of this thesis to study the effects of the temperature and strain profile of the stabilization process, and the resulting carbon fiber tensile properties. In addition, the precursor fibers used were spun under two different draw ratios, to study the effects of the spinning parameters. Results indicated through DMA studies that completeness of stabilization reactions can be gauged by the peak and leveling of induced stress while fibers are stabilized in isostrain conditions. Through this method, carbon fiber tensile properties were maintained from the prior methods, but saved significant time for processing. Stress vs. strain tests throughout the stabilization process created a baseline for understanding the maximum capable strain on fibers throughout the stabilization process. Lastly, this information was summarized, combined, and basic mechanical engineering principles discussed for a continuous stabilization furnace with strain control, so that further research into the stabilization process can incorporate carbon fibers made with in situ stretch control.

Carbon nanotubes have been studied for nearly two decades and their amazing properties continue to spur intense investigation in the area of polymer composites. In terms of potential commercialization, mutiwall carbon nanotubes (MWCNTs) are currently the most prevalent and economically viable form of nanotubes. Uncovering innovative means to take full advantage of their properties remains a fundamental issue. In this thesis, viability of their use to reinforce polymeric systems is reported. Acrylonitrilebutadiene- styrene (ABS) was used as the host matrix. MWCNTs were introduced to the ABS matrix via melt compounding. The resulting composite was thoroughly rheologically, thermally, and mechanically characterized. Several applications were also experimentally studied. The composites fatigue performance is measured and compared to a typical micron sized carbon fiber. These results indicate that both the nano and micron scale carbon fibers reduce the resistance to fatigue failure. The mechanism of failure in both cases appears to be different and is discussed. The use of microwave energy is investigated for the use of heating purposes. Results show a distinct advantage over conventional heating methods. Microwaves allow for volumetric, fast, selective, and controllable heating of the ABS system.

In this work, the stability of acid-modified activated carbons is assessed in the typical biomass conversion reaction environment of 200 °C, 17 bar water. Activated carbons were modified with a variety of common liquid and gas phase methods and characterized. Acid-modified carbon catalysts were exposed to hot liquid water for 24 h and further characterized to determine the effect of this exposure on their surface chemistry. It was found that the liquid phase acidifying agents of H₂SO₄ and HNO₃ are most effective at adding acidic functionalities to the carbon. Exposure to hot liquid water was found to significantly decrease the carboxylic and sulphonic acid site concentrations on the carbons and slightly increased lactonic group concentrations. Kinetic studies indicate that these surface chemical changes occur within the first 4 h exposure to this environment, and that increased exposure temperature results in more efficient acid site removal. XPS measurements show that H₂SO₄ modification imparts partially stable sulfonic acid groups on the carbon surface while HNO₃ modification imparts nitro groups which are unstable at exposure temperatures above 150 °C. The second part of this work focuses on the application of these acid-modified activated carbon catalysts as well as a variety of mixed metal oxide catalysts to the hydrolysis of the model biomass compound cellobiose. Catalyst screening reactions indicate that amorphous silica alumina catalysts are stable and selective but only slightly active whereas silica niobia catalysts are highly active but less selective and stable. Modified activated carbon catalysts were found to have moderate activity and selectivity. An investigation into the mechanism of silica niobia deactivation was performed and apparent activation energies were found for cellobiose hydrolysis over a variety of mixed metal oxide catalysts. Finally, a novel activated carbon synthesis mechanism was developed based on knowledge of surface site stability. This carbon catalyst was found to be highly active, selective, and stable for cellobiose hydrolysis but further characterization is required to fully understand its effectiveness as a catalyst.

The National Aeronautics and Space Agency NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) platform carried by Terra and Aqua satellites, is providing systematic measurements summarized in high quality, consistent and well-calibrated satellite images and datasets ranging from reflectance in the visible and near infrared bands to estimates of leaf area index, vegetation indices and biome productivity. The objective of this research was to relate the spectral responses and derived MODIS products of ecosystems, to biogeochemical processes and trends in their physiological variables. When different sources of data were compared, discrepancies between the MODIS variables and the corresponding ground measurements were evident. Uncertainties in the input variables of MODIS products algorithms, effects of cloud cover at the studied pixel, estimation algorithm, and local variation in land cover type are considered as the cause. A simple "continuous field" model based on a physiologically-driven spectral index using two ocean-color bands of MODIS satellite sensor showed great potential to track seasonally changing photosynthetic light use efficiency and stress-induced reduction in net primary productivity of terrestrial vegetation. The model explained 88% of the variability in Flux tower-based daily Net Primary Productivity. Also a high correlation between midday gross CO2 exchange with both daily and 8-day mean gross CO2 exchange, consistent across all the studied vegetation types, was found. Although it may not be possible to estimate 8-day mean Light Use Efficiency reliably from satellite data, Light Use Efficiency models may still be useful for estimation of midday values of gross CO2 exchange which could then be related to longer term means of CO2 exchange. In addition, the MODIS enhanced vegetation index shows a high potential for estimation of ecosystem gross primary production, using respiration values from MODIS surface temperature, providing truly per-pixel estimates. / Department of Natural Resources and Environmental Management

Nitrate (NO3-) is a ubiquitous groundwater contaminant in agricultural and wastewater discharge areas. The prediction of microbial mediated NO3- removal in subsurface environments requires an understanding of the rates at which electron donors are utilized by denitrifying microbes. This study focuses specifically on the following organic carbon compounds as electron donors: glucose, acetate, adenine, cysteine and fulvic acid. Six triplicate series of flow through reactors (FTRs) containing 35 cm3 of natural, organic-poor sediment were supplied for 10 weeks with solutions containing nitrate and the individual carbon compounds, along with a no-carbon added control. The organic carbon compounds were selected to yield a range of different types of organic carbon (sugars, amino acids etc.) as well as a range of Gibbs Free Energy (???G) values when their oxidation is coupled to denitrification. The initial flow rate of the FTRs was 1 ml h-1. Once steady NO3- concentrations were reached in the outflow, the flow rate was increased to 2 ml h-1 and, subsequently, 4 ml h-1. Potential denitrification rates (RD) measured for the different carbon substrates spanned a range of 0 to 114 nmol cm-3 h-1. Fulvic acid did not induce denitrification, while acetate yielded the highest rate. The outflow solutions for FTRs supplied with adenine and cysteine contained ammonia and sulfate, respectively. These results are consistent with the molecular structure of adenine, which contains an amine group, and of cysteine, containing an amine and thiol group. The results show that the addition of C-substrates to the sediment promotes denitrification, and the rate at which it occurs are dependant on which C-substrate is provided. RD results were used to determine if the denitrification rates imposed by the different carbon substrates could be predicted using theoretical approaches such as ???GR or the nominal oxidation state of carbon (NOSC). However, predictions determined by thermodynamics alone were not significantly correlated with the observed trends in denitrification rates.

This study geochemically characterized a proposed Carbon Capture and Storage project in northeast British Columbia, and presents new dissolution kinetics data for the proposed saline aquifer storage reservoir, the Keg River Formation. The Keg River Formation is a carbonate reservoir (89-93% Dolomite, 5-8% Calcite) at approximately 2200 m depth, at a pressure of 190 bar, and temperature of 105 °C. The Keg River brine is composed of Na, Cl, Ca, K, Mg, S, Si, and HCO3 and is of approximately 0.4 M ionic strength. Fluid analysis found the Keg River brine to be relatively fresh compared with waters of the Keg River formation in Alberta, and to also be distinct from waters in overlying units. These findings along with the physical conditions of the reservoir make the Keg River Formation a strong candidate for CO2 storage. Further work measured the dissolution rates of Keg River rock that will occur within the Keg River formation. This was performed in a new experimental apparatus at 105 °C, and 50 bar pCO2 with brine and rock sampled directly from the reservoir. Dissolution rate constants (mol!m-2s-1) for Keg River rock were found to be Log KMg 9.80 ±.02 and Log KCa -9.29 ±.04 for the Keg River formation. These values were found to be significantly lower compared to rate constants generated from experiments involving synthetic brines with values of Log KMg -9.43 ±.09, and Log KCa -9.23 ±.21. Differences in rates were posited as due to influences of other element interactions with the >MgOH hydration site, which was tested through experiments with brines spiked with SrCl2 and ZnCl2. Results for the SrCl2 spiked solution showed little impact on dissolution rates with rate constants of Log KMg -9.43 ±.09, and Log KCa -9.15 ±.21, however the ZnCl2 spiked solution did show some inhibition with rate constants of Log KMg -9.67 ±.04, and Log KCa -9.30 ±.04. Rate constants generated in this work are among the first presented which can actually be tested by full-scale injection of CO2. / Graduate

No description available.

Novel carbon materials such as carbon onions, nanotubes and amorphous carbon (a-C) are technologically important due to their useful properties. Normally synthesised using plasmas, their growth mechanisms are not yet fully understood. For example, the growth mechanism of the high density phase of a-C, tetrahedral amorphous carbon (ta-C), has been a subject of debate ever since its discovery. The growth mechanism of carbon nanostructures such as carbon onions and nanotubes is also not well known. The aim of this thesis is two-fold. Firstly, to provide insight into the growth of carbon films, in particular, the driving force behind the formation of diamond-like bonding in a-C which leads to ta-C. Secondly, to investigate the growth of carbon onions and other sp2 bonded carbon nanostructures such as nanotubes. To achieve the first aim, carbon thin films were deposited using cathodic arc deposition at a range of ion energies, substrate temperatures and Ar background gas pressures. These films were characterised using electron microscopy techniques to examine their microstructure, density and sp3 content. It was found that the formation of the ta-C is due to a stress-induced transition whereby a critical stress of 6.5±1.5 GPa is needed to change the phase of the film from highly sp2 to highly sp3. Within this region, a preferentially oriented phase with graphitic sheets aligned perpendicular to the substrate surface was found. By investigating the role of elevated temperatures, the ion energy-temperature

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / This study area for this research is characterised by a regional anticline plunging to the east-south-east with large-scale internal architecture comprising transgressive, retrogradationally stacked stratigraphy that dips gently landward and is unconformably truncated by overlying sealing units. The primary reservoir/aquifer targets for CO₂ injection are palaeo-shoreline parallel nearshore sandstone bodies characterised by high porosity and permeability and good interconnectivity. The key regional sealing unit is the Lakes Entrance Formation, which consists of mudstone and marl capable of sealing large columns of CO₂. The proposed stategy for CO₂ geosequestration is to inject CO₂ outside four-way structural closure to allow up-dip fluid migration to the north then west governed by the structure of regional sealing units. Probabilistic estimates of CO₂ capacity utilising the proposed strategy indicate that 1395-2575 Mtonnes could be sequestered. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1281480 / Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2007

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / This study area for this research is characterised by a regional anticline plunging to the east-south-east with large-scale internal architecture comprising transgressive, retrogradationally stacked stratigraphy that dips gently landward and is unconformably truncated by overlying sealing units. The primary reservoir/aquifer targets for CO₂ injection are palaeo-shoreline parallel nearshore sandstone bodies characterised by high porosity and permeability and good interconnectivity. The key regional sealing unit is the Lakes Entrance Formation, which consists of mudstone and marl capable of sealing large columns of CO₂. The proposed stategy for CO₂ geosequestration is to inject CO₂ outside four-way structural closure to allow up-dip fluid migration to the north then west governed by the structure of regional sealing units. Probabilistic estimates of CO₂ capacity utilising the proposed strategy indicate that 1395-2575 Mtonnes could be sequestered. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1281480 / Thesis (Ph.D.) -- University of Adelaide, Australian School of Petroleum, 2007