Doctor of Philosophy, University of Akron, 2024, Polymer Engineering

Many important processes such as friction, adhesion, wetting, and adsorption that are relevant to a wide, multidisciplinary community and industries occur at material interfaces. What traditional methods to characterize these interfacial properties often lack is the ability to obtain direct, in situ molecular information which can be correlated to the property of interest. Vibrational spectroscopy tools such as attenuated total reflectance infrared (ATR-IR) and sum frequency generation (SFG) spectroscopy represent methods that, with some ingenuity, allow us to obtain this information for any surface or interface which is optically accessible. While SFG represents a highly surface/interface-specific technique, ATR-IR provides information up to 1 micron within a sample; thus, the two methods can be complementary. Between these two methods, new information can be gained for a variety of material interfaces. To this end, we have first employed SFG and ATR-IR together to quantify the “real” contact area, or the area over which materials make molecular contact. Results highlight the effectiveness of these tools in terms of sensitivity compared to other methods and provide evidence of the extent of molecular contact for systems of varying roughness and modulus. Additionally, we use SFG and ATR-IR to connect the molecular-scale picture of a polyelectrolyte (charge-bearing) brush as it absorbs water in humid air and relate these properties to sliding friction. Results of this investigation reveal a new transition phenomenon to create sharply switchable friction, and its link to the molecular-scale structure of the brush. Finally, we employ ATR-IR in a more applied sense in an attempt to quantitively analyze the concentration of additives on the surface of rubber compounds. Our investigation highlights the potential usefulness of FTIR spectroscopy in general for rapid quantitative analysis directly on samples of interest without any prior chemical separation.

Committee: Ali Dhinojwala (Advisor); Fardin Khabaz (Committee Chair); Kevin Cavicchi (Committee Member); Abraham Joy (Committee Member); Jutta Luettmer-Strathmann (Committee Member) Subjects: Materials Science; Physical Chemistry; Physics

Master of Science (MS), Ohio University, 2023, Chemical Engineering (Engineering and Technology)

Phenolic-coal composites are a potential class of thermosetting composites that could offer enhanced thermal stability due to the similarity in aromatic macromolecular structures of the filler and polymer. Evaluating the curing kinetics of the composite can provide insight into the dynamics of bond formation in this composite during heat curing. This study employed Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) to investigate the thermal properties and curing kinetics of phenolic resin and coal mixtures. The cured phenolic-coal composite samples were characterized using Fourier transform infrared spectroscopy (FTIR), to evaluate the interaction between coal filler and the polymer network and correlate coal structure and thermal behavior. The two ranks of coal studied were sub-bituminous coal (Powder River Basin) and bituminous coal (Itmann) at 10% and 40% weight content filler weight percentages. From the TGA, 60% Phenolic-PRB mix (Pmix) had the highest weight loss at 11-12%, while the 60% Phenolic-Itmann (Imix) records the least as 6%. DSC Isoconversional analyses indicated 60% Phenolic-PRB mix had the highest activation energy: 142±8 kJ/mol, while the 60% Phenolic- Itmann mix yielded the lowest range of activation energy values: 85±5 kJ/mol. In comparison, the pure phenolic resin has activation energies in the range of 128 – 135 kJ/mol. The difference in curing activation energy and post-cured vibrational spectroscopy between the composite systems could be attributed to more reactive functional end groups present in the PRB coal. The higher level of interaction observed in the sub-bituminous coal and phenolic mix confirms an enhanced polymeric behavior. Overall, the results from this study provide a basis for the fabrication of phenolic-coal thermoset composites tailored for different applications through modified end properties of cured phenolic resins based on the choice of coal ranks as fillers.

Committee: Valerie Young (Advisor); Eric Stinaff (Committee Member); Jason Trembly (Committee Member); Damilola Daramola (Committee Chair) Subjects: Chemical Engineering; Chemistry; Materials Science; Molecules

Doctor of Philosophy, The Ohio State University, 2023, Food Science and Technology

Consumer demands for ethically sourced and environmentally friendly food products have led to development efforts to replace animal-based proteins with plant-based alternatives. However, plant-based protein ingredients can be limited by their functional and sensory properties, and thus processing techniques to improve these properties must be explored. Enzymatic hydrolysis has been suggested to improve key functional properties, such as solubility, but the research methodology in this area is questionable and hydrolysis does not fully address sensory deficits in plant-protein ingredients, notably bitterness. In this dissertation, commercial extruded snack products containing soy protein hydrolysates were used as a model to quantify bitterness and test the viability of reformulation with flavor maskers or alternatively processed proteins to improve off-flavor. This study revealed that commercial flavor maskers are not effective at reducing bitterness in products containing soy hydrolysate, but soy protein hydrolysates made by different manufacturers with different processing methods proved a viable replacement with improved off-flavor. In search for conclusive evidence that enzymatic hydrolysis results in improved functionality, a review of literature was conducted. This review concluded that enzymatic hydrolysis process may result in the formation of insoluble aggregates, which in most studies are removed by centrifugation or filtration during processing, thus artificially increasing the reported solubility values for plant-protein hydrolysates. The phenomenon of hydrolysis induced aggregation was confirmed for protein isolates from soy and as well as a pulse protein alternative to soy, chickpea, which were hydrolyzed by Flavourzyme and Alcalase. Analysis of physical and structural properties of the hydrolyzed proteins revealed that hydrolysis led to protein destabilization, causing hydrogen-bond mediated aggregation during thermal enzyme inactivation. The knowledge (open full item for complete abstract)

Committee: Farnaz Maleky (Advisor); Osvaldo Campanella (Committee Member); Emmanuel Hatzakis (Committee Member); John Litchfield (Committee Member); Lynn Knipe (Committee Member) Subjects: Biochemistry; Food Science

MS, University of Cincinnati, 2022, Engineering and Applied Science: Materials Science

Conducting polymers have multiple applications, such as for corrosion protection and anti-static coatings. Studied across disciplines, conducting polymers continue to be an advantageous alternative to their metal counterparts given their flexibility, low density, and tunable electronic properties. Polyaniline (PANi) and polypyrrole (PPy) have good conductivity but can be difficult to use individually due to poor solubility, fusibility, and processability. Samples with four PANi to PPy ratios and dopants were characterized to determine if, when combined, the material is more soluble, fusible, and processable. Thermal degradation of the materials was measured using a thermogravimetric analyzer (TGA) and a differential scanning calorimeter (DSC). Activation energy for material changes, such as dopant loss and polymer degradation, was found by analyzing TGA results using the Kissinger method. The DSC data were used to determine degradation rate, glass transition temperature, and melting temperature. Chemical properties were determined using ultraviolet–visible (UV-Vis) spectroscopy and Fourier-Transform Infrared (FTIR) spectroscopy. Three Uv-Vis bands were observed in the PANi/PPy samples and the absorbance ratios of the materials were all around 0.04, indicating that they are alternating copolymers. FTIR spectroscopy was used to determine the chemical structure of the material, as well as conjugation length and degree of oxidation of PANi, using the benzenoid/ quinoid ratios. Based on the combination of 1250 cm-1 and 1100 cm-1 bands from FTIR spectra, it was determined that most of the samples were copolymers. The DSC cooling curves showed that all samples except the 40/60 PANi/PPy sample were amorphous copolymers. The strong crystallization peak around 100 oC suggests the 40/60 PANi/PPy sample was a semi-crystalline copolymer. All PANi/PPy samples show promise to improve processability and thermal stability.

Committee: Jude Iroh Ph.D. (Committee Member); Mark Schulz Ph.D. (Committee Member); Yoonjee Park Ph.D. (Committee Member) Subjects: Materials Science

Doctor of Philosophy, Case Western Reserve University, 2022, Macromolecular Science and Engineering

Polymer processing is a fundamental key to achieve the desired properties to reach the needs of polymer applications. Thus, it is important to understand how the processing can contribute to material characteristics during the extrusion, while they are being processed. That is why this work propose a method able to perform analyses of the material while it is being processed during the extrusion: the on-line Fourier transform infrared (FTIR) spectroscopic system. The system consists of a device that was designed to be able to couple a commercial infrared spectrometer to an twin-screw extruder. On-line FTIR measurements can be done in different locations along the extruder barrel. Pearson VII function was used improving the linearity of mixture composition, which is proposed by Beer-Lambert's law, by around 14% when compared to the traditional methods. Polymer blends of polypropylene (PP) and polyamide 6 (PA6) at different weight composition ratio were used to validate the on-line system during extrusion. The area ratio between the IR bands at 1640 cm-1 (υC=O) and 1373 cm-1 (σC-H3) were measured on-line for all the blend compositions and shown to be in good agreement with off-line measurements. When the reactive blending of polyamide 6 (PA6) and polypropylene grafted with acrylic acid (PP-g-AA) (in blends of 80%/20% and 30/70% of PP-g-AA and PA6, respectively) was investigated along the extruder length, a increase of the IR band area ratio (1640/1373 cm-1) was achieved when the process condition aggressiveness in mixing was improved due to the generation of fresh interface between the two phases, as it is shown through scanning electron microscopy (SEM). Trough on-line FTIR measurements it was possible to visualize the development of the reactive blending reaction of PP-g-AA/PA6 blends inside the extruder. For example, different process conditions lead to the same or different amount of reaction (IR area ratio 1640/1373 cm-1) at the end of the extruder, but they fo (open full item for complete abstract)

Committee: Joao Maia (Advisor); Joao Maia (Committee Chair); Sebastiao V. Canevarolo (Committee Member); Gary E. Wnek (Committee Member); Jennifer L. W. Carter (Committee Member); Hatsuo Ishida (Committee Member); Leonardo Canto (Committee Member) Subjects: Engineering; Materials Science; Plastics; Polymers

MS, University of Cincinnati, 2020, Engineering and Applied Science: Environmental Engineering

Biochar produced from the spent coffee grounds is an effective method for carbon sequestration, soil, and water remediation, improved agricultural yields and potential mercury removal from the air as a precursor to the specialized activated carbon. The primary goal of this study was to investigate the feasibility of zero waste technology as an extended part of the previous research on bio-diesel extraction from the spent coffee grounds and to produce biochar for heavy metal removal from the aqueous media. The pyrolysis technology was applied on the spent coffee grounds and the effects of reaction temperature, carrier gas and feedstock on the product was studied both qualitatively and quantitatively. The yield and pH of biochar samples from SCG1 and SCG4 under different temperatures and gases, were compared. ICP-MS was used for batch analysis for metal adsorption. The performance was compared under different initial concentrations of metal ions. The Langmuir and Freundlich curves were established to better understand the adsorption isotherms and effect of initial concentration. Surface area of the bio-chars were measured and FTIR analysis was conducted to understand the functional groups presence on the surface. For SCG4, the maximum biochar yield of 67.22 percent and 55.23 percent by weight were obtained at 300 degrees Celsius in CO2 gas and N2 gas, respectively. For SCG4, the minimum biochar yield of 42.4 percent and 40.57 percent by weight were obtained at 550 degrees Celsius in CO2 gas and N2 gas, respectively. For SCG1, the maximum biochar yield of 43.04 percent and 42.23 percent by weight were obtained at 300 degrees Celsius in CO2 gas and N2 gas, respectively. For SCG1, the minimum biochar yield of 29.39 percent and 31.70 percent by weight were obtained at 550 degrees Celsius in CO2 gas and N2 gas, respectively. The maximum and minimum density of bio-chars were 0.39 g/cc and 0.52 g/cc for SCG4-CO2-300 and SCG4-N2-550, respectively. The mult (open full item for complete abstract)

Committee: Mingming Lu Ph.D. (Committee Chair); Sivaraman Balachandran Ph.D. (Committee Member); Zhiqiang (Mark) Wang Ph.D. (Committee Member); Yan Mei Zhou Ph.D. (Committee Member) Subjects: Environmental Engineering

Master of Science (M.S.), University of Dayton, 2020, Electro-Optics

As the range of applications for electro-optic materials continues to grow, so does the need to identify and characterize new materials with improved electro-optic responses. A promising electro-optic material which has yet to be widely utilized is Lead Magnesium Niobate-Lead Titanate (PMN-PT) ceramic. In an effort to better characterize and understand the material, this work employed FTIR spectroscopy to calculate the refractive index of PMN-PT over a wide range of optical frequencies. Through analysis of interference fringes, the dispersion curve is calculated between 10,500 cm-1 and 1200 cm-1 (approximately 955 nm and 8.3 μm) containing nearly two thousand data points with an assumed accuracy of three decimal places. Additionally, capacitance bridge analysis is used to characterize the effect of temperature on the dielectric constant of PMN-PT. Special attention is given to the relationship of refractive index and dielectric constant so that a temperature study of the dielectric constant can be used to infer additional physical characteristics of PMN-PT.

Committee: Paul McManamon Ph.D. (Advisor) Subjects: Electrical Engineering; Electromagnetics; Experiments; Materials Science; Optics; Physics

PhD, University of Cincinnati, 2020, Engineering and Applied Science: Materials Science

Material characterization techniques has been more and more applied to aerosol monitoring. Developing low cost, compact, hand-portable and direct-reading instruments for aerosol monitoring have attracted significant research interests. Respirable crystalline silica (RCS) is a major hazard to the occupational health by inhalation. Material characterization techniques such as X-ray diffraction (XRD) and infrared spectrophotometry have been employed to the quantification of RCS. The drawbacks of current techniques can be overcome by two vibrational spectroscopy methods: quantum cascade laser (QCL)- based infrared spectroscopy and Raman scattering spectroscopy. The main focus of this dissertation is to develop methods using low cost and hand-portable instruments for near real-time measurement of RCS using vibrational spectroscopy. In Chapter 2 and Chapter 3, a QCL-IR system was developed to quantify airborne concentrations of RCS. Three sampling methods were investigated for their potential for effective coupling with QCL-IR based transmittance measurements. Spectral analysis methods were developed to obtain IR spectra from the collected particulate samples. The new instrument was calibrated, and the results were compared with standardized methods based on Fourier transform infrared (FTIR) spectrometry. The QCL-IR method was extended to measurement of respirable a-quartz concentrations in workplace aerosols generated during cutting of fiber- reinforced cement and natural stone building products using a power saw, as well as in aerosol generated from various coal mine dust. Results show that significantly lower detection limits for RCS (˜330 ng), compared to conventional infrared methods, could be achieved with effective micro-concentration and careful coupling of the particulate sample with the QCL-IR beam. These results offer promise for further development of sensitive filter-based laboratory methods and portable sensors for near real-time measurement of crystalline (open full item for complete abstract)

Committee: Gregory Beaucage Ph.D. (Committee Chair); Jude Iroh Ph.D. (Committee Member); Pramod Kulkarni D.Sc. (Committee Member); Vesselin Shanov Ph.D. (Committee Member) Subjects: Materials Science

Master of Science in Pharmaceutical Science (MSP), University of Toledo, 2019, Pharmaceutical Sciences (Industrial Pharmacy)

Solid state characterization is commonly performed to find a drug candidate with optimal properties for early development or to find a form with different properties to improve a formulation in later development. As a matter of fact, repurposing or reformulating older drugs may help bypass part of the copious cost and time needed for validation and authorization of new therapeutic compounds. Therefore, a variety of solid form screening can be performed to find or develop the right polymorph, salt, co-crystal, solvates/hydrates or amorphous dispersion of pharmaceutical drug candidate. Using a combination of analytical techniques, this study revised the physiochemical characterization of Kanamycin sulfate and its hydrated crystals. The methodology entailed primarily of diffraction techniques, vibrational spectroscopy and thermal analysis. The morphological study was carried out using Scanning Electron Microscopy (SEM).

Committee: Jerry Nesamony PhD (Advisor); Gabriella Baki PhD (Committee Member); Caren Steinmiller PhD (Committee Member) Subjects: Analytical Chemistry; Chemistry; Pharmaceuticals; Pharmacy Sciences

MS, University of Cincinnati, 2019, Engineering and Applied Science: Environmental Engineering

The growing and pervasive presence of plastic pollution has attracted considerable interest in recent years, especially small (< 5 mm and > 100 nm) plastic particles known as `microplastics' (MPs). These particles are thought to pose greater risks than larger plastic debris as they are more likely to be ingested by many species. Their widespread presence may pose a threat to marine organisms globally. Contamination of freshwater and terrestrial systems also has been reported, and more recent studies indicate the presence of even smaller (= 100 nm) plastic particles, termed `nanoplastics' (NPls), that may have unique risks due to their nanoscale. Most of the nano and microplastic (N&MP) pollution in marine environments is assumed to originate from land-based sources, but their sources, transport routes, and transformations are uncertain. Information on freshwater and terrestrial systems is lacking, and data on NPl pollution is particularly sparse. The shortage of systematic studies of freshwater and terrestrial systems is a critical research gap because estimates of plastic release into these systems are much higher than those for oceans. As most plastic pollution originates in urban environments, studies of urban watersheds, particularly those with high population densities and industrial activities, are especially relevant with respect to source apportionment. Released plastic debris is transported in water, soil, and air. It can be exchanged between environmental compartments, adsorb toxic chemicals, and ultimately be carried long distances, with potential to cause both physical and chemical harm to a multitude of species. Unfortunately, these processes are not well understood. Measurement challenges and a lack of standardized methods has slowed progress in determining the environmental prevalence and impacts of N&MPs. An overall aim of this project is to report the sources and abundances of N&MPs in urban watersheds. Their fate, transport, transformations, and (open full item for complete abstract)

Committee: Dionysios Dionysiou Ph.D. (Committee Chair); Souhail Al-Abed Ph.D. (Committee Member); Margaret Kupferle Ph.D. (Committee Member); Phillip M. Potter Ph.D. (Committee Member) Subjects: Environmental Engineering

Master of Science, Miami University, 2019, Geology and Environmental Earth Science

Three groups of fluorapatite from the Mont Saint-Hilaire igneous complex in Quebec, Canada have been analyzed with scanning electron microscopy (SEM), electron probe microanalyses (EPMA), single-crystal X-ray diffraction (SCXRD), Fourier transform infrared spectroscopy (FTIR), and magic angle spinning nuclear magnetic resonance (MAS-NMR) to fully characterize the chemical and structural details of fluorapatite from one of the most mineralogically diverse locales on Earth. SEM and EPMA revealed these fluorapatites to be enriched in Th, Y, and Na, while FTIR showed substantial concentrations of carbonate substituting for phosphate at the tetrahedral site. The Th contents observed in these fluorapatites are the highest ever observed for natural samples, and have implications for designing new solid nuclear waste forms. SCXRD refinements revealed the dissymetrization of two of the three groups from the classic P63/m space group to the P-3 space group due to the elevated Y and Na contents. Lastly, the FTIR and NMR data show the presence of the long debated C-F bond the observation of which has important implications for the incorporation of carbonate groups into apatites, and is the first time this bond has been observed in any natural mineral.

Committee: John Rakovan Dr (Advisor); Claire McLeod Dr (Committee Member); Mark Krekeler Dr (Committee Member) Subjects: Geochemistry; Geology; Mineralogy

Doctor of Philosophy, University of Akron, 2018, Polymer Science

Fossil energy from coal, gas, and oil-based fuel stocks remains a vital cornerstone of the global energy infrastructure while contributing over half of annual CO2 emissions. Rising global CO2 concentrations and aberrant trends in climate have sparked recent scrutiny of the energy industry sustainability. Carbon capture, utilization, and storage (CCUS) at the site of power plants has been proposed as a strategy for mitigating atmospheric CO2. This dissertation covers simulated and experimental models designed to address key problems in both the fundamental science and applied engineering of amine-functionalized silica sorbents for carbon capture from few molecule DFT (density functional theory) calculation to kilogram-scale technology validation. DFT was used to emulate small molecule and polymeric amines with good agreement in four successive series of models. (i) The concept of CO2 adsorption strength on secondary amines was investigated which revealed lone amine sites produce weakly adsorbed species while dense amine pairs yield strongly adsorbed species. (ii) Mixed amine types are common in blended or polymeric amine systems and convolute data interpretation. The hydrogen bonding ability of ammonium carbamate pairs demonstrated significant dependence on amine type and local hydrogen bond partners. (iii) Fixation of amines onto substrates is a ubiquitous strategy for preparing CO2 sorbents. The effect of geometric constraint imposed by immobilization was investigated for simulated propylamine pairs. Binding energy was linearly dependent on the alignment of ammonium carbamate. FTIR features were categorized into four groups. (iv) Selective formation of carbamic acid was studied by modeling reactants, intermediates, transition states (TS), and products of the amine-CO2 reaction on simulated diamine substrates. It was shown that significant reduction in TS activation energy occurred by Grotthus-like proton hopping. Coal-fire power plant CO2 capture was experime (open full item for complete abstract)

Committee: Steven Chuang (Advisor); Mesfin Tsige (Committee Chair); Tianbo Liu (Committee Member); Stephen Cheng (Committee Member); David Perry (Committee Member) Subjects: Chemical Engineering; Chemistry; Materials Science; Physical Chemistry; Polymers

Doctor of Philosophy (PhD), Ohio University, 2017, Civil Engineering (Engineering and Technology)

The use of warm mix asphalt (WMA) technologies and recycled materials, such as reclaimed asphalt pavement (RAP) in the pavement industry has increased widely in the past few years due to their various economic and environmental benefits. Consequently, these topics have garnered the interest of many researchers, and have led to many studies that have evaluated the performance and durability of such pavements. One of the main issues concerning WMA pavements is the binder aging. Since WMA is produced at lower temperatures than conventional hot mix asphalt (HMA) mixtures, the binder is expected to experience lower aging level as compared to HMA. Hence, studying the aging properties of WMA binders is essential in the evaluation of the performance of WMA pavements. For the use of RAP in asphalt mixture, there are concerns about the blending between the RAP and virgin binders in the mixture and the properties of the blend within the interfacial blending zone surrounding the aggregates. This dissertation is divided into two major parts: the first part evaluates aging in foamed warm mix asphalt and the second part evaluates blending properties between virgin binders and RAP binders. This was done at mainly a microscale level using Atomic Force Microscopy (AFM). Part 1 was presented in chapter 3. This part specifically evaluates the effects of aging on the micro-mechanical and chemical properties of foamed WMA and HMA asphalt materials. Two asphalt binders that met the performance grade of PG 70-22 and PG 64-22 were considered. Atomic force microscopy (AFM) was used to examine the micromechanical and adhesion properties of the asphalt binders considered at different aging conditions. In addition, Fourier-transform infrared spectroscopy (FTIR) and gel permeation chromatography techniques were used to identify the changes in the chemical composition of different asphalt binders due to aging. A rolling thin-film oven (RTFO) and pressure aging vessel (PAV) methods were utili (open full item for complete abstract)

Committee: Munir Nazzal (Advisor) Subjects: Civil Engineering

Master of Science, The Ohio State University, 2017, Food Science and Technology

In 2002, significant amounts of acrylamide were detected in some foods processed at high temperatures. Acrylamide is a known animal carcinogen and classified as possibly carcinogenic to humans by the International Agency for Research on Cancer (IARC). Current assays for acrylamide depend on expensive techniques, for example gas chromatography mass spectroscopy (GC-MS) and liquid chromatography tandem mass spectroscopy (LC-MS/MS) both of which require time consuming preparatory steps that produce hazardous waste. Generally, these methods require food producers to send samples out rather than perform in-house acrylamide testing. There is a need in the food industry to develop simpler, low-cost, and sensitive methods for routine monitoring of acrylamide in foods. Vibrational spectroscopy combined with chemometrics provides an alternative to chromatography that requires little sample preparation. Our objective was to develop a simple screening technique based on handheld and portable near-infrared (NIR) and mid-infrared (mid-IR) devices to detect acrylamide content in french fries. Frozen french fries (n=95) were kindly provided by an industry partner. They were manufactured by frying samples in ten second intervals that ranged from 0 minutes to 6 minutes. Acrylamide content of the french fry samples were determined using the QuEChERS method as a clean-up step and quantification using GC-MS. Frozen french fries were blended down into a powder and spectra were collected and analyzed by partial least squares regression (PLSR) to develop calibration models for predicting acrylamide content in french fries. NIR and mid-IR showed good linear correlation between spectra and acrylamide levels (r > 0.92). NIR and mid-IR had standard error of validation (SEV) values of 200 µg/kg. The results suggest that handheld and portable spectrometers allow detection and quantification of acrylamide through spectral signature profiles enabling for real-time and field-based measu (open full item for complete abstract)

Committee: Luis Rodriguez-Saona Dr. (Advisor); Christopher Simons Dr. (Committee Member); Lynn Knipe Dr. (Committee Member) Subjects: Food Science

Doctor of Philosophy, University of Akron, 0, Polymer Engineering

A new, simple, and efficient Gas Jet Fiber (GJF) spinning process was used for fabrication of polymer precursor fibers from polymer precursor sol solutions with diameters ranging from a few hundreds of nanometers to a few micrometers, which on subsequent calcination in air resulted in the production of semiconducting metal oxides (SMO) nanofibers. One of the primary objectives of this research work was to fabricate SMO nanofibers for use in photocatalytic oxidation of toxic volatile organic compounds (VOCs) that cause indoor air pollution and to degrade organic pollutants in water treatment applications. Another objective was to create specific arrangements of inorganic oxide or ceramic components in the same nanofibers so as to obtain morphologies that exhibit interesting physico-chemical properties useful in photocatalytic applications. The basic strategy adopted in this work included a synergy of wet precursor sol-gel chemistry and GJF spinning followed by thermal treatment for the synthesis of ceramic nanofibers. First, we investigated and optimized the process for fabrication of titanium dioxide (TiO2), vanadium pentoxide (V2O5), and tin-doped indium oxide (ITO) nanofibers. TiO2 nanofibers exhibited a significantly higher (i.e., almost one order of magnitude) UV-light driven ethanol photocatalytic oxidation rate compared to a commercial grade P25 TiO2 nanoparticles. Second, the production of SMO nanofibers with core-shell (CS) and side-by-side (SBS) configurations was studied for a pair of inorganic oxides. TiO2, ITO, and V2O5 were used for fabrication of bi-component CS and SBS nanofibers. Third, the fabrication strategy for hierarchical V2O5-TiO2 nanostructure from a homogeneous sol solution of a mixture of SMO precursors and polymer in volatile solvents was developed. Nanofibers were successfully obtained with diameters below 200 nm exhibiting a hierarchical `nanorods-on-nanofiber' morphological form as a result of calcination of (open full item for complete abstract)

Committee: Sadhan Jana Dr. (Advisor); Darrell Reneker Dr. (Committee Member); George Chase Dr. (Committee Member); Steven Chuang Dr. (Committee Member); Xiong Gong Dr. (Committee Member); Bryan Vogt Dr. (Committee Chair) Subjects: Chemical Engineering; Chemistry; Nanoscience; Nanotechnology; Polymer Chemistry; Polymers

Doctor of Philosophy, University of Akron, 2016, Polymer Engineering

This work is a part of collaborative project between Multidisciplinary University Research Initiative (MURI) through which an advanced polymeric capacitor films for military applications were designed. Two of those novel polymers were PPOH (hydroxyl functionalized isotactic polypropylene with comonomer of 10-hydroxy-1-undecen) and PI(BTDA-DAH) (Polyimide 3,',4,4'-benzophenone tetracarboxylic dianhydride and 1,6-diaminohexan). This dissertation focused on the effect of processing conditions on the mechano-optical behavior of PPOH and PI(BTDA-DAH). Firstly, the real-time mechano-optical behavior of PPOH containing 0.4 mol % comonomer and its comparison with unmodified polypropylene (PP) were studied in the partially molten state during processing cycle of heating, stretching, annealing, and cooling. It was revealed that the crystalline network dominated the material response during the processing cycle for both polymers. However, the presence of hydrogen bonding between the hydroxyl groups in PPOH was found to affect the structural evolution of the PPOH copolymer significantly more than compared to the PP homopolymer. Secondly, the real-time mechano-optical behavior of PI(BTDA-DAH) was studied in the glassy and the rubbery states as a function of processing temperature and stretching rate during uniaxial deformation. Thee regimes of stress optical behavior were revealed. First, at the early stage of deformation the stress optical rule is observed; birefringence linearly increased with a stress optical constant of 17.8 GPa-1 - regime I. Second, a deviation from linearity took place. At higher temperature and/or lower stretching rate the deviation is positive and the birefringence rapidly increases while the stress slowly increases- regime II. At lower temperature and/or higher stretching rate this deviation of linearity is negative- regime IIIa. Third, in cases where regime II is revealed, it was followed by a negative deviation of birefringence (open full item for complete abstract)

Committee: Mukerrem Cakmak Ph.D (Advisor); Robert Weiss Ph.D. (Advisor); Mark Soucek Ph.D (Committee Chair); Abraham Joy Ph.D (Committee Member); Chrys Wesdemiotis Ph.D (Committee Member) Subjects: Polymers

Master of Science, University of Akron, 2016, Geology

This study is part of a larger project titled, “In Situ Shallow Subsurface Spectroscopy (S4 Initiative)” which is focused on furthering the research on shallow subsurface spectroscopic and geochemical prospecting of archaeological deposits in situ. The long term goal is to create a geochemical instrument for subsurface prospection and characterization of soil conditions in an archaeological and forensic context. The specific purpose of this study was to establish laboratory detection limits of four potential human decomposition products (leucine, calcium pyrophosphate, oleic acid, and palmitic acid) under a variety of soil conditions and demonstrate their applicability to human burial analogues under field conditions. Detection limits were determined under laboratory conditions by collecting ATR-FTIR spectra on soil samples to which known concentrations of the four human decomposition products had been added. The soil used was collected from three locations representing a variety of texture classes (particle size) and organic matter contents. A similar process was utilized to detect the compounds in soil samples taken from two sites where pigs had been buried as human analogues. Soil cores taken from the “pig dig” sites allowed for the effectiveness of the detection limits to be tested using sample analogues of human burials under field conditions. All four of the human decomposition products were detected in the samples to which they had been added, though no significant relationships to either particle size or organic matter content were observed. Detection limits ranged from 1.0% - 0.04% for leucine, 4.0% - 0.05% for calcium pyrophosphate, 0.10% - 0.01% for oleic acid, and 1.0% - 0.01% for palmitic acid in all samples. ATR-FTIR spectral peaks representative of one or more fatty acids were present in some of the cores in both of the human burial analogues, however peaks representative of leucine and calcium pyrophosphate were not present in any of the co (open full item for complete abstract)

Committee: Linda Barrett Dr. (Advisor); Timothy Matney Dr. (Committee Member); John Senko Dr. (Committee Member) Subjects: Archaeology; Environmental Geology; Forensic Anthropology; Geochemistry; Geology; Soil Sciences

Master of Science (M.S.), University of Dayton, 2016, Materials Engineering

Despite numerous studies on thermoset resin systems, understanding of the influence of chemical network structure on mechanical properties is still premature. Recently multiscale simulations combining quantum mechanics and molecular mechanics have provided an unprecedented pathway for property prediction for a wide range of polymeric systems. Experimental guidance, validation, and refinement of these models are currently in high demand; therefore, this study focused on systematic experimentation to fabricate an epoxy resin system with known chemical structure and controlled processing conditions with spectroscopic characterization of the products for insight on the resultant chemical network structure. Finally, detailed thermomechanical and fracture mechanics studies were conducted to connect the chemistry with the processing and the mechanics. Atomistic simulations were performed in parallel on similar material systems. Key findings of this study include molecular conversion using IR spectroscopy and its relationship with glass transition temperature and fracture toughness, the illustration of etherification of epoxy resins during curing, and the influence of molecular weight on reactivity with the crosslinking agent. All of these experimental findings are significant assets for parameterization of on-going multiscale models and essential stepping-stones for improving the fidelity of these models and implementing these tools for property prediction.

Committee: Donald Klosterman Ph.D. (Committee Chair); Rajiv Berry Ph.D. (Advisor); Charles Browning Ph.D. (Committee Member); Dhriti Nepal Ph.D. (Committee Member) Subjects: Materials Science

Doctor of Philosophy, Case Western Reserve University, 2015, Physics

Van der Waals (vdW) materials are layered structures bonded by the weak vdW force. As such, stable single atomic layers can be isolated either by mechanical exfoliation or chemical methods as chemical vapor deposition. Atomically thin vdW materials have emerged as new types of two-dimensional (2D) systems with unique electronic and optical properties that are distinct from that of their bulk counterparts. Studies of this new class of material are not only interesting fundamentally; they can potentially also lead to applications in next-generation electronics and optoelectronics devices. In this thesis, we investigate two prototypes of 2D vdW materials, graphene (a semimetal) and semiconducting transition metal dichalcogenides (TMD) based on optical spectroscopy. Electro-magnetic radiation ranging from the far-infrared (or terahertz (THz)) to the visible has been utilized to investigate two questions: (1) the excitonic effects in Mo/W dichalcogenides; and, (2) the free carrier response in graphene. For the first topic, exciton series in monolayer WSe2 and the effect of electric field on the excitons is studied. A exciton series of WSe2 is observed by a complimentary measurement of linear absorption and two-photon photoluminescense excitation (2PPLE). Strong exciton binding energy ($\sim$ 0.4 eV) and non-Rydberg series are observed arising from 2D screening of Coulomb interactions. Using field-effect transistor structures we apply electrostatic doping and/or perpendicular electric field to WSe2 monolayer through the gates. Trion peak is observed under doping, which further splits under high electric fields. This phenomenon can be explained by Rashba spin-orbit interaction induced spin sub-bands hybridization. For the second topic, the free carrier response in monolayer graphene is investigated using the Fourier transform infrared (FTIR) spectroscopy in steady state conditions and the optical pump-THz probe spectroscopy under non-equilibrium conditions. We ob (open full item for complete abstract)

Committee: Jie Shan (Committee Chair); Kenneth Singer (Committee Member); Jesse Berezovsky (Committee Member); Philip Feng (Committee Member) Subjects: Physics

Doctor of Philosophy, University of Akron, 2014, Chemical Engineering

The surface of semiconductors, such as TiO2, has long been shown to have the capability of activating adsorbed molecules and converting the photon energy to chemical energy. The activation of adsorbed molecules occurs when electron-hole pairs are generated upon exposure to light of appropriate energy and their charges are transferred to the adsorbed molecules. This dissertation presents a fundamental study on four photocatalytic reactions on TiO2, focusing on the charge transfer processes and their subsequent influence on the reaction mechanisms. For this purpose, thermal reduction of TiO2 in H2, water dissociation on UV-irradiated TiO2, and photocatalytic degradation of benzene and ethanol were studies, using an in-situ IR spectroscopic approach. In-situ IR spectroscopy allows monitoring the interaction between the adsorbed molecules and the catalyst surface and the formation of reaction products. In addition, in-situ IR approach is capable of providing evidence for accumulation of photogenerated electrons in the conduction band of TiO2, observed as a structureless IR adsorption (i.e., background shift) in the 1000 to 3000 cm-1 region. As TiO2 was reduced in H2, an IR absorbance band was observed around 1015 cm-1. Since the similar band was not observed in Ar and O2, the formation of this band was attributed to the removal of lattice oxygen atoms and formation of Ti3+ sites on the reduced TiO2. UV photoexcited TiO2 under H2 environment caused the rise of IR background indicating the accumulation of electrons in conduction band. The accumulation of photogenerated electrons in the conduction band was attributed to the promotion effect of photogenerated holes in accepting electrons from H-H bond breaking. The injection of electrons from H2 oxidation into the photogenerated holes was found to hinder the dissociation of H2O to OH on TiO2. On the surface of TiO2, five IR bands at 3727, 3692, 3681, 3664, and 3632 cm-1 were distinguished corresponding to stret (open full item for complete abstract)

Committee: Steven Chuang Dr. (Advisor); David Perry Dr. (Committee Member); Edward Evans Dr. (Committee Member); George Chase Dr. (Committee Member); Hamid Bahrami Dr. (Committee Member) Subjects: Chemical Engineering; Chemistry