Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Absorption (1)
- Activated Carbon Fibers (1)
- Activation (1)
- Carbonaceous Pitch (1)
- Cellulose Nanocrystals (1)
-
- Chlorine (1)
- Colloidal chemistry (1)
- Foldamer (1)
- Fuel Cell Poisoning (1)
- Helical structure (1)
- Hydrogen Activation (1)
- Impurity Effects (1)
- Light Scattering (1)
- MALDI (1)
- META-POLY(PHENYLENE ETHYNYLENE) (1)
- Melt extrusion modeling (1)
- Mesophase (1)
- Molecular dynamics (1)
- Nafion-Pt/C (1)
- Nanocomposite (1)
- PEMFC (1)
- PH (1)
- Packing (1)
- Petroleum Chemistry (1)
- Petroleum Pitch (1)
- Polymer (1)
- Pore Structure (1)
- Precursor Composition (1)
- Pt/C (1)
- Quantitative Analysis (1)
- Publication
Articles 1 - 8 of 8
Full-Text Articles in Engineering
Quantitative Analysis And Structural Characterization Of Carbonaceous Pitches, Sourabh Kulkarni
Quantitative Analysis And Structural Characterization Of Carbonaceous Pitches, Sourabh Kulkarni
All Dissertations
Both petroleum pitches and pitches derived from pure polycyclic aromatic hydrocarbons (PAHs) are oligomeric materials that can serve as precursors for a wide variety of advanced carbon materials. The goal of this study was the structural characterization and quantitative analysis of the dominant constituent oligomers and species present in these pitches.
A key requirement for such work is the ability to fractionate these complex mixtures into samples of narrow molecular weight distribution (mol wt; MWD) that can be used as standards. To this end, semicontinuous (or semibatch) dense-gas/supercritical extraction (DGE/SCE) was used to produce monomer, dimer, and trimer fractions of …
Modeling And Synthesis Of Functionalized Meta-Poly(Phenylene Ethynylene) Helical Structures, Ha Nguyen
Modeling And Synthesis Of Functionalized Meta-Poly(Phenylene Ethynylene) Helical Structures, Ha Nguyen
All Dissertations
The ability of meta-poly(phenylene ethynylene) (mPPE) materials to undergo random coil to helix conformational changes under select conditions affords many opportunities for their use in sensor, separation, catalysis, and bio-related applications. Thus, to advance the development of these materials, a modeling procedure based on replica exchange molecular dynamics (REMD) simulation was developed to reliably assess factors affecting the folding behaviors of functionalized mPPE variants in solution. A combinational modeling study of 20 functionalized mPPEs in five solvent conditions provided insight into how mPPE secondary structure is impacted by the complex relationship between mPPE functional groups and solvent moieties. Further, these …
Pitch-Based Activated Carbon Fibers: The Effect Of Precursor Composition On Pore Structure, Halil Tekinalp
Pitch-Based Activated Carbon Fibers: The Effect Of Precursor Composition On Pore Structure, Halil Tekinalp
All Dissertations
Although researchers have previously investigated the effect of precursor differences on the final properties of activated carbon fibers (ACFs), those precursors were not well-characterized. In particular, detailed information about their molecular composition and anisotropy was not available.
In this study, seven oligomeric fractions, each of well-defined composition and molecular weight (mol wt) distribution, were isolated from a commercially produced isotropic petroleum pitch (i.e., Marathon M–50) and used for the production of ACFs. Four of these precursors of varying oligomeric composition were fully isotropic and three contained different levels of mesophase, so that the effects of molecular composition and molecular order …
Chlorine Absorption Utilizing Caustic Sodium Sulfite, Henry Mcdonald
Chlorine Absorption Utilizing Caustic Sodium Sulfite, Henry Mcdonald
All Theses
A scrubber was required to abate a waste stream containing chlorine gas created in the electrolytic dissolution step of the aqueous polishing process at the Mixed Oxides Fuel Fabrication Facility at Savannah River Site, South Carolina. A method of absorption that utilized caustic sodium sulfite as the scrubbing agent was studied for implementation in the process. This method was found to be highly efficient with respect to process requirements, and it was also found to provide enhanced performance over the more conventional method of chlorine scrubbing which uses only aqueous sodium hydroxide as a reagent. Sulfite provides an additional advantage …
Light-Emitting Nanocomposites And Novel Amorphous Polymers For Optical Applications, Kyle Gipson
Light-Emitting Nanocomposites And Novel Amorphous Polymers For Optical Applications, Kyle Gipson
All Dissertations
Polymeric optical materials generally are comprised of amorphous polymers that are transparent in at visible wavelengths but exhibit strong absorption bands in the near-infrared making them less useful for many optical applications. Attenuation, which is the absorption per unit length, largely results from the high vibrational energy associated with carbon-hydrogen bonds contained in the polymer backbone. Attenuation can be mitigated by optical amplification utilizing light emitting additives. Investigated in this dissertation are synthesis techniques for the fabrication of light-emitting polymer nanocomposites and their resultant thermal and rheological characteristics for potential use as polymer optical fibers or films.
Inorganic nanocrystals doped …
Effects On Hydrogen Adsorption And Activation On Platinum In A Fuel Cell Catalyst, Jack Zhang
Effects On Hydrogen Adsorption And Activation On Platinum In A Fuel Cell Catalyst, Jack Zhang
All Dissertations
Proton exchange membrane fuel cells are a highly efficient source of power generation that is needed to sustain the energy demands of today's more environmentally conscience society. However, the presence of impurities in the hydrogen fuel stream, such as CO, H2S, and NH3 from the steam reforming/partial oxidation of hydrocarbons/methanol, can severely poison the Pt electrocatalyst present in the fuel cell electrode causing degradation in the fuel cell performance. To counter these poisoning effects, fuel cell manufacturers are forced to use higher Pt loadings, which dramatically increases material costs and prevents the successful commercialization of the technology. …
Oxygenate Synthesis During Co Hydrogenation On Cocuzno- Based Catalysts, Yu-Tung Tsai
Oxygenate Synthesis During Co Hydrogenation On Cocuzno- Based Catalysts, Yu-Tung Tsai
All Dissertations
The research of catalytic synthesis of methanol and other higher alcohols from CO hydrogenation has received great attention since 1980s. The focus of this research is to establish a better fundamental insight into heterogeneous metal catalysts for oxygenate (especially alcohol) synthesis by CO hydrogenation.
Co-based catalysts have been reported widely as the high-performance Fischer-Tropsch Synthesis (FTS) catalysts. The solid base, hydrotalcite (HT), using as a support for Co catalysts resulted in higher activity for CO hydrogenation comparing to other supports (pre-calcined hydrotalcite, MgO and Al2O3). The activities of Co/HT reduced at different reduction temperatures (300-600oC) were …
Cellulose Nanocrystals Properties And Applications In Renewable Nanocomposites, Esteban Urena Benavides
Cellulose Nanocrystals Properties And Applications In Renewable Nanocomposites, Esteban Urena Benavides
All Dissertations
Development of novel bio-based nanocomposites is fundamental to reduce the dependence on fossil resources and provide a sustainable future. In light of this global problem, cellulose nanocrystals (CNCs) have raised interest due to their remarkable mechanical properties. Adequate design of nanocomposites requires a fundamental understanding of how the structure affects the mechanical properties of the material. However, contradictory results in the literature have revealed a lack of comprehension of this relationship for CNC based composites. Consequently, this work provides an explanation to unusual results for CNC nanocomposites presented in the literature and demonstrates the ability to achieve property enhancements in …