Doctor of Philosophy, University of Akron, 2008, Polymer Science

We have studied the ability of aromatic fluorocarbons with different levels of fluorination to interact with aromatic hydrocarbons via pi-pi stacking interactions. To observe this behavior, we investigated the radical copolymerization behavior of styrene and 1-vinylnaphthalene (M1) with fluorinated styrenes (M2) by determining the monomer reactivity ratios using the Fineman-Ross, Kelen-Tudos and nonlinear least square curve-fitting methods. To aid in the study, fluorinated styrenes [2,3,5,6-tetrafluorostyrene (TEFS), 2,4,6-trifluorostyrene (TFS), 2,4-difluorostyrene (DFS) and 4-fluorostyrene (4FS)] and 1-vinylnaphthalene (1VN) were synthesized using either Ni-catalyzed Kumada cross-coupling of aryl Grignard reagents with vinyl bromide, or reaction of the aryl Grignard reagents with acetaldehyde followed by dehydration using P2O5. The copolymerization of styrene (St) with 2,3,4,5,6-pentafluorostyrene (PFS, rStrPFS = 0.17, 0.16, 0.048 and 0.069 in bulk at 70 °C, in toluene at 70 °C, in bulk at 25 °C and in toluene at 25 °C, respectively) generates copolymers that tend to be alternating, with the alternating tendency increasing with decreasing temperature, according to the monomer reactivity ratios from the nonlinear least square fit of the Mayo-Lewis plot; the alternating tendency is independent of dilution or solvent. In contrast, the copolymerizations of styrene with 4FS (rStr4FS = 0.62 at 70 °C in bulk; rStr4FS = 0.69 at 25 °C under redox conditions) give ideal copolymerizations, with the monomer reactivity ratios being independent of temperature. The glass transition temperatures (Tg) of the St-PFS copolymers are elevated relative to their mole-average values, whereas the Tg values of the St-4FS copolymers correspond to their mole-average values. The water and ethylene glycol contact angles of the St-PFS are between those of the corresponding homopolymers and increase with increasing content of fluorinated comonomer. The same behavior is observed for the water con (open full item for complete abstract)

Committee: Coleen Pugh (Advisor); Roderic Quirk (Committee Chair) Subjects: Polymers

Master of Science, The Ohio State University, 2023, Food, Agricultural and Biological Engineering

Ninety-six well-cell culture plates are a staple in labs due to their cost-effective nature, wide range of materials and colors, and usages for a variety of testing. Despite the variety of well-plates available, there are still adjustments required to fit the needs of an experiment, which can be completed via 3D printing technology. There is also a need for a 96 well-plate material to be altered to produce a recycle, biocompatible plate. The objective of this research is to create a 96 well-plate used for biological testing composed of poly(styrene-b-isobutylene-b-styrene) (SIBS) and a filler material to fulfill the need for a biocompatible, flexible, and recyclable well-plate by using 3D printing technology. Shore A hardness is an empirical test to measure the resistance a rubber has to indentation. The hardness of flexible mold rubbers SIBS has a shore A hardness of 43.7, but at least 50 is required to successfully print the filament. The research question investigated in this work was: What methods can increase the shore A hardness of SIBS so that it can be effectively used as a filament in a 3D Printer? Therefore, SIBS with mixed with filler materials, carbon black (CB) and silica, in an effort to increase the shore A hardness. By running these compounds into a filistruder, filament with a 1.75 ± 0.5 mm diameter, which is considered an ideal, commercial diameter for 3D printing was produced. This filament was run through a MakerBot Replicator 2X 3D printer in attempts to print a 96 well-plate. The SIBS/butyl/CB mixture was unsuccessful in being extruded by the nozzle. The SIBS/silica ± butyl mixture filament was able to be extruded but did not successfully print a 2cm by 2 cm cube. This was hypothesized to have been due to uneven dispersion of the silica. These findings suggest that SIBS can be mixed with additional materials with better dispersion to successfully print a 96 well-plate, and that further research is needed to identify the optimal mixture.

Committee: Judit Puskas (Advisor); Ann Christy (Committee Member) Subjects: Engineering

MS, University of Cincinnati, 2009, Engineering : Mechanical Engineering

This study developed a 3D numerical model of a ventilation setup inside a Fiberglass Reinforced Plastic (FRP) boat-manufacturing plant, and simulated the flow inside this plant. The study also investigated two alternate ventilation systems, and compared the results with those for the existing ventilation system. Ventilation systems are installed in FRP boat-manufacturing plants to remove harmful contaminants, mainly styrene, emitted during manufacture of boats. Adopting a suitable ventilation system is an inexpensive way of reducing styrene exposure to workers and, hence, is investigated for an existing manufacturing plant. First, a 2D study of a typical ventilation system is carried out, with the goal to understand the general flow pattern inside the plant. Steady-state results established that styrene accumulates near the ground because it is denser than air, suggesting that a ventilation system should include a ground-level exhaust to remove much of the styrene. A subsequent 3D model of an actual ventilation setup in a manufacturing plant is developed based on data obtained from the National Institute for Occupational Safety and Health (NIOSH). Results from an unsteady simulation showed, again, that styrene, being heavier than air, stayed close to the floor. The average velocity in the working area of the boat was determined to be 0.65 m/s, suggesting little ventilation in the area. Also, after evaporation from the boat surface, styrene was being not forced towards the exhaust vents located downstream. Based on these results, two alternate ventilation systems are investigated. The first one involves ground-level exhausts near the working area to remove much of styrene. The second system involves inlet air blowers placed closer to ground, i.e., at 0.91 meters from the floor, as compared to 3.96 meters in the original system, to push styrene accumulating near the floor, towards the exhaust vents located downstream. Results predict that the first alternate ventilat (open full item for complete abstract)

Committee: Urmila Ghia PhD (Advisor); Karman Ghia PhD (Committee Member); Milind Jog PhD (Committee Member) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 1967, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, University of Akron, 2022, Polymer Science

Novel modifications of styrene-butadiene rubber were studied using conventional curatives, sulfur curing packages or peroxides, to efficiently utilize supramolecular reinforcement strategies that improve the mechanical properties of rubber. Thiol-ene coupling proved to be an effective method for modifying styrene-butadiene rubber during peroxide curing, but it was inadequate when attempted during sulfur vulcanization. Supramolecular reinforcement was achieved by grafting mercapto-functionalized sodium phosphate esters to styrene-butadiene rubber during peroxide curing which electrostatically associate. The association strength between these ionic grafts played a critical role in determining the degree of reinforcement. Possible mechanisms by which reinforcement occurs were discussed and, at low grafting densities, at least one mechanism was determined not to play a major role. It was shown that substantial modification of cis-1,4-polyisoprene does not occur by thiol-ene coupling and that another chemical means must be used to modify this substrate. Reagents consisting of thioaldehydes derived from thiosulfinates were used in Alder-ene reactions to modify cis-1,4-polyisoprene. Based on this chemistry, new grafting and crosslinking agents were developed that react quickly and at relatively low temperatures. Important elements in the molecular design of these curatives were discussed and it was demonstrated that good mechanical properties are attainable.

Committee: Li Jia (Advisor); Mark Foster (Committee Chair); Shing-Chung Wong (Committee Member); Tianbo Liu (Committee Member); James Eagan (Committee Member) Subjects: Chemistry; Materials Science; Molecular Chemistry; Morphology; Nanoscience; Nanotechnology; Organic Chemistry; Polymer Chemistry; Polymers

Doctor of Philosophy in Materials Science and Engineering, Youngstown State University, 2022, Materials Science

Common failure modes to Big Area Additive Manufacturing (BAAM) are the phenomenon of slumping and excessive distortion. Slumping or sagging usually occurs when the printed structure retains excessive heat. This phenomenon is commonly seen when the build has insufficient cooling between layers and, therefore, inadequate mechanical strength due to the high-temperature material properties to support the layers above. Distortion is the planar deviation from the desired geometry. Significant residual stresses typically distort BAAM builds. Stresses often occur due to the thermal cycling and large temperature gradients found in additively manufactured parts. This study developed a transient thermal and structural simulation model to predict the slumping phenomenon and distortion, specifically applicable to overhanging features. A pyramidal model was crafted in Ansys Workbench software to simulate a large layer overhang to investigate the necessary slumping conditions. The pyramid was designed to have 53 layers and utilized symmetry to reduce the pyramid to one-quarter of the overall size and was modeled using standard ABS material. The simulation model matches the dimensions in the experimental pyramid, which had bead dimensions of 12.5 mm wide with a thickness of 5 mm. The overall structure size was 1.06 m by 0.77 m by 0.43 m. Each layer in the model independently allows for element birth/death commands and individual layer mesh parameters. The built-in element birth/death commands enable the layers to activate and progress the same way as the experimental build. As each new layer is activated, a temperature input of 200°C is applied then turned off just as the next layer is activated. The feedstock material selected for this study is Acrylonitrile Butadiene Styrene (ABS), which was selected based on the physical properties and the availability of the temperature-dependent material properties. The availability of these temperature-dependent material properties is ess (open full item for complete abstract)

Committee: Kyosung Choo Ph.D. (Advisor); Jae Joong Ryu Ph.D. (Committee Member); Donald Priour Ph.D. (Committee Member); Brian Cockeram Ph.D. (Committee Member); Matthew Caputo Ph.D. (Committee Member) Subjects: Engineering; Materials Science; Mechanical Engineering

Master of Science in Polymer Engineering, University of Akron, 2021, Polymer Engineering

Many basic properties of polymer such as viscoelasticity, rubber elasticity and solidification temperatures are derived from the long, chain like nature of the molecules. At the same time the detailed chemical structure is used to fine tune the properties, such as the solubility and transition temperature. More varied properties are obtained by copolymerization of chemically distinct monomers. In this thesis, we report our studies on quaternized copolymers synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. Two types of polymers are prepared by either first quaternizing one monomer, vinyl benzyl chloride, and copolymerizing with styrene or copolymerizing vinyl benzyl chloride and styrene and then quaternizing the polymer. The synthesized polymers were characterized by NMR, thermogravimetric analysis and differential scanning calorimetry to determine the differences in the microstructure and resultant material properties of the polymers synthesized by pre- and post-polymerization quaternization of the vinyl benzyl chloride groups in the polymer.

Committee: Kevin Cavicchi (Advisor); Weinan Xu (Committee Chair); Mark D. Soucek (Committee Member) Subjects: Materials Science; Polymer Chemistry; Polymers

Master of Science, University of Akron, 2021, Polymer Science

As reinforced rubber is a widely used and essential material, numerous research studies have been conducted on it, but many questions remain because of the complexity of the filler networks. To achieve a better performance tire tread rubber, the technique of X-ray photon correlation spectroscopy (XPCS) has been used in the study of the microscopic dynamics of filler reinforced styrene-butadiene rubber (SBR) subjected to step strain. For the two-time plots, dynamic heterogeneity for two kinds of SBR samples, with and without S1 silane coupling agent, was observed. The susceptibility (휒 function) was employed to analyze the dynamical heterogeneity evidenced in the two-time correlation data quantitatively. The plots of maximum 휒 values at three different values of scattering vector, 푞, versus aging time show that dynamic heterogeneity decays in a few hundred seconds. A more detailed analysis shows that the dynamic heterogeneity of the sample with coupling agent decays in the first 75 s after stretching. Combined with the maxima 휒 versus scattering vector 푞 plots which have shown two different patterns, the deduction is that addition of a silane coupling agent effectively accelerates the decay of dynamic heterogeneity, but does not apparently influence the magnitude of 휒. According to previous research, the time at which 휒 reaches a maximum coincides with the relaxation time and the maximum value of 휒 indicates the magnitude of the dynamic heterogeneity. Plots of maximum 휒 value versus q and delay time make clear the trends in most of the measurements. For a given value of 푞, the delay time at which the maxima 휒 value occurs increases with aging time. In both samples, trends in 휒, such as how it varies with 푞 and at which delay time the maximum occurs, are similar for the stretching direction and perpendicular direction. However, further study indicates that the initial strong dynamic heterogeneity declines more slowly in the direction perpendi (open full item for complete abstract)

Committee: Foster Mark Dr. (Advisor); Tsige Mesfin Dr. (Committee Member) Subjects: Polymers

Doctor of Philosophy, Case Western Reserve University, 2021, Macromolecular Science and Engineering

Polymers are used in a wide variety of applications and are present in all aspects of people's daily lives; however, they are generally very flammable. Major advances have been made in developing flame retardants (FRs) to be used in polymers, but most commercial FR additives used today, mainly halogenated substances, are toxic to humans and the environment and are being increasingly banned throughout the world. Acrylonitrile-butadiene-styrene (ABS) is one of the most widely used polymers in the world but also one of the most flammable and most challenging to flame retard, and ABS is used commercially with toxic halogenated FRs. Research into the use of renewable products as FRs for polymers has grown exponentially, but very little work has been performed on reducing ABS's flammability using nature-derived or low-toxicity FRs. There is therefore an urgent need for the development of low-toxicity, bio-based FR systems to substitute halogenated FRs for commercial use in ABS. The present work aims to contribute to the development of a bio-based flame-retardant solution for ABS, by (1) developing a flame-retardant grade of ABS using mainly nature-derived additives while maintaining acceptable mechanical properties and (2) comprehending the flame-retardation mechanisms of the bio-based FRs. The project consists of two phases: (1) a Screening Phase, during which the effects of 8 different FRs and combinations thereof on ABS's flammability are evaluated, using Design of Experiments techniques, through microscale combustion calorimetry; and (2) a Detailed Analysis and Mechanistic Study Phase, in which the most promising candidates from Phase 1 are further analyzed through a variety of techniques with the objectives of better understanding their flammability and mechanical performances and comprehending their flame-retardation mechanisms. Chapter 1 presents a brief introduction and a literature review. Chapter 2 contains the experimental methodology. Chapter 3 discusses th (open full item for complete abstract)

Committee: David Schiraldi (Advisor); Jonathan Pokorski (Advisor); José Roberto d'Almeida (Advisor); Gary Wnek (Committee Member); Hatsuo Ishida (Committee Member); Ya-Ting Liao (Committee Member); Mônica Naccache (Committee Member); Amanda Brandão (Committee Member) Subjects: Engineering; Materials Science; Polymers

Master of Science, University of Akron, 2019, Polymer Engineering

Pyrolyzed soybean hulls (PSBH) is a renewable, low cost and eco-friendly biomass material which has large potential to be used as reinforcement filler for partial replacement of carbon black (CB) in styrene butadiene rubber (SBR). Pyrolysis is a process that use high heating rate in anoxic condition to convert biomass into clean and renewable carbon products. In this research, the possibility of replacing carbon black with four types of PSBH was investigated with CB replacement by PSBH in reinforcement filler varying from 0 to 30%. The effect of ball mill treatment on morphology and chemical properties of PSBH were also analyzed. The results showed that ball mill treatment reduced the particle size dramatically. The optimum concentration of PSBH in reinforcement filler was determined to be 5% to achieve relatively good properties in comparison to those obtained using CB only. In addition, ball milled PSBH filled rubber compounds showed higher tensile strength and strain at break but lower moduli at 10% and 100% strain compared to untreated PSBH.

Committee: Erol Sancaktar (Advisor); Ruel McKenzie (Committee Member); Tainbo Liu (Committee Member) Subjects: Polymer Chemistry; Polymers

Master of Science in Mechanical Engineering (MSME), Wright State University, 2018, Mechanical Engineering

Three-dimensional (3D) printing, a subset of additive manufacturing, is currently being explored heavily for actual part fabrication due to its ability to create complex objects with intricate internal features. There are several 3D printing technologies; however, the extrusion-based technology such as fused deposition modeling (FDM) is the widely used one owing to its low cost. The FDM method can be used to fabricate parts with different fill densities, fill patterns, and process parameters such as extruder temperature and print speed. In this research, influence of process parameters such as extruder temperature and speed on the physical characteristics such as the shape and the size of printed fibers in each layer, the fiber distance, and the fiber-to-fiber interface are investigated. In addition, their effects on mechanical characteristics of the printed samples are examined and interpreted with respect to the layer physical characteristics. To accomplish this, phononic metastructure specimens are fabricated using acrylonitrile butadiene styrene (ABS) polymer on a Maker Bot 2X Replicator 3D printer. Three different extrusion temperatures (210o, 230o, and 250o C) and print speeds (100 mm/s, 125 mm/s, 150 mm/s) are considered with an infill density of 50%. Optical microscopy is performed for layer physical characterization while the compression and hardness tests are done to evaluate the mechanical properties such as the hardness, failure strength, yield strength and compressive modulus. It is observed that the print head speed has minimal effect on mechanical properties; however, an improvement in mechanical properties are observed at higher temperature. Also, the lower temperature results in more uniform features within the layers as compared to those printed at higher extruder temperature.

Committee: Ahsan Mian Ph.D. (Advisor); Raghavan Srinivasan Ph.D., P.E. (Committee Member); Joy Gockel Ph.D. (Committee Member) Subjects: Mechanical Engineering

Master of Science, University of Akron, 2018, Polymer Engineering

Torrefied sorghum (TS) is considered an attractive, eco-friendly, renewable and low cost reinforcement filler that can be used for partial or full replacement of carbon black (CB) in styrene butadiene rubber (SBR). Torrefaction is a process that uses heat in a low oxygen environment to convert plant biomass into a cleaner, renewable filler. In this research, the possibility of replacing carbon black with torrefied sorghum was investigated for concentrations of TS in reinforcement filler varying from 0 to 100%. In addition, the effects of ball mill treatment on the morphological and chemical structures of TS and properties of the filled rubber compound were also analyzed. The results showed that ball mill treatment reduced the particle size of TS and the degree of crystallinity of the cellulose in TS, while lignin was much more stable. The optimum concentration of TS in reinforcement filler was ~30% to obtain properties comparable to those obtained using CB only. These included mechanical properties and cure behavior along with higher wet-skid resistance and lower rolling resistance due to adequate filler-filler and filler-rubber interactions in the rubber matrix. Ball milled TS filled rubber compound showed higher tensile strength and strain at break but lower moduli at 2% and 100% strain compared to the untreated TS filled one.

Committee: Erol Sancaktar (Advisor); Ruel McKenzie (Committee Chair); Coleen Pugh (Committee Member) Subjects: Engineering; Polymer Chemistry; Polymers

Master of Science in Mechanical Engineering (MSME), Wright State University, 2017, Mechanical Engineering

Three-dimensional (3D) printing, a form of Additive manufacturing (AM), is currently being explored to design materials or structures with required Electro-Mechanical-Physical properties. Microstrip patch antennas with a tunable radio-frequency (RF) response are a great candidate for 3D printing process. Due to the nature of extrusion based layered fabrication; the processed parts are of three-layer construction having inherent heterogeneity that affects structural and functional response. The purpose of this study is to identify the relationship between the anisotropy in dielectric properties of AM fabricated acrylonitrile butadiene styrene (ABS) substrates in the RF domain and resonant frequencies of associated patch antennas and also to identify the response of the antenna before and after a low velocity impact. In this study, ANSYS high frequency structure simulator (HFSS) is utilized to analyze RF response of patch antenna and compared with the experimental work. First, a model with dimensions of 50 mm x 50 mm x 5 mm is designed in Solidworks and three separate sets of samples are fabricated at three different machine preset fill densities using an extrusion based 3D printer LulzBot TAZ 5. The actual solid volume fraction of each set of samples is measured using a 3D X-ray computed tomography microscope. The printed materials appeared to exhibit anisotropy such that the thickness direction dielectric properties are different from the planar properties. The experimental resonant frequency for one fill-density is combined with ANSYS-HFSS simulation results to estimate the bulk dielectric constant of ABS and the equivalent dielectric properties in planar and thickness directions. The bulk dielectric properties are then used in HFSS models for other two fill densities and the simulated results appear to match reasonably well with experimental findings. The similar HFSS modeling scheme was adopted to understand the effect of material heterogeneity on RF response. In (open full item for complete abstract)

Committee: Ahsan Mian Ph.D. (Advisor); Raghavan Srinivasan Ph.D. (Committee Member); Joy Gockel Ph.D. (Committee Member) Subjects: Aerospace Engineering; Automotive Engineering; Design; Electrical Engineering; Mechanical Engineering; Mechanics; Plastics; Technology

Master of Science in Mechanical Engineering (MSME), Wright State University, 2017, Mechanical Engineering

This research focuses on the energy absorption capability of additively manufactured or 3D printed polymer lattice structures of different configurations. The Body Centered Cubic (BCC) lattice structure is currently being investigated by researchers for energy absorption applications. For this thesis, the BCC structure is modified by adding vertical bars in different arrangements to create three additional configurations. Four designs or sets of the lattice structure are selected for comparison including BCC, BCC with vertical bars added to all nodes (BCCV), BCC with vertical bars added to alternate nodes (BCCA), and BCC with gradient arrangements of vertical bars (BCCG). Both experimental and finite element modeling approaches are used to understand the load-displacement as well as energy absorption behavior of all four configurations under both quasi- static compression and low-velocity impact loadings. Once designed in SolidWorks, all four sets of samples were prepared using Acrylonitrile Butadiene Styrene (ABS) polymer material on a Stratasys uPrint 3D printer. The Instron universal testing machine was used for the quasi-static loading test whereas an in-house built ASTM Standard D7136 drop tester was used to capture the impact response. For impact samples, sandwich panels were fabricated using the 3D printed ABS lattice core structures. In this case, four Kevlar face sheets were attached to the lattice core structure using a two-part epoxy adhesive. The absorbed energy was found by integrating the area under the load-displacement curve for both compression and impact tests. To interpret the results, Specific Energy Absorption (SEA) that is the absorbed energy over the mass, should be considered. Moreover, the investigation of the SEA was also performed using Finite Element Analysis (FEA) for comparison. ANSYS Workbench was used to predict the behavior of the lattice structures under compression load. However, Abaqus Dynamic Explicit was used to capture (open full item for complete abstract)

Committee: Ahsan Mian Ph.D. (Advisor); Raghavan Srinivasan Ph.D. (Committee Member); Maher Amer Ph.D. (Committee Member) Subjects: Aerospace Engineering; Design; Mechanical Engineering; Mechanics

Doctor of Philosophy, The Ohio State University, 1973, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

Doctor of Philosophy, The Ohio State University, 1952, Graduate School

Committee: Not Provided (Other) Subjects: Chemistry

MS, University of Cincinnati, 2012, Engineering and Applied Science: Materials Science

Supercapacitors are devices that store large amount of charge. Supercapacitors can play a key role in the drive towards a cleaner and greener environment. This research focuses on the properties of electrochemical cells and the application of conductive polymer composites as effective electrode materials in a supercapacitor. The effect of electrochemical cell parameters like distance of separation, electrolyte and separator material on the overall capacitance was studied. An innovative two electrode cell design was developed to facilitate these measurements. Conductive polymer composites were prepared using physical milling and pressed into pellets using hot pressing and normal pressing techniques. The characterization of conductive polymer composite electrode based supercapacitors was carried out using electrochemical impedance spectroscopy, cyclic voltammetry and chronopotentiometry. The performance of two polymers (polyaniline and acrylonitrile butadiene styrene) with different levels of conductivity was compared, in order to understand the double layer capacitance and pseudo-capacitance mechanisms. The surface properties, crystal structure and chemical composition were analyzed using scanning electron microscopy, energy dispersive spectroscopy and x-ray diffraction.

Committee: Relva Buchanan ScD (Committee Chair); Rodney Roseman PhD (Committee Member); Dale Schaefer PhD (Committee Member) Subjects: Materials Science

Master of Science in Chemical Engineering, University of Toledo, 2005, Chemical Engineering

Hydroformylation reactions in supercritical carbon dioxide provide an environmentally conscious method of producing aldehydes for fine chemical and pharmaceutical products. Asymmetric ligands, such as (R)-BINAP, may be used to provide an enantioselective product. The benefits of producing a selective product include an overall reduction in costs, including those costs associated with separation and disposal of undesired and potentially harmful products. When these reactions are performed in environmentally benign solvents, such as supercritical carbon dioxide (scCO2), additional environmental benefits are derived, such as ease of recycling of the solvent and unconverted reactants and elimination of the need for organic solvents. In this study, rhodium based catalysts were prepared in supercritical carbon dioxide and evaluated for the hydroformylation of styrene to produce 2-phenylpropionaldheyde. Triphenylphosphine and (R)-BINAP were examined as ligands and their effects on the reaction were examined. The experiments showed that a catalyst is produced that promotes hydroformylation of styrene in supercritical carbon dioxide and that enantiomeric selectivity could be obtained using (R)-BINAP ligands.

Committee: Martin Abraham (Advisor) Subjects: Engineering, Chemical

Master of Science (MS), Ohio University, 1990, Chemical Engineering (Engineering)

Nitrogen-compound removal by ion exchange: A model system study of the effect of nitrogen-compound type on the removal performance of two sulfonated styrene/divinylbenzene ion-exchange resins

Committee: Michael Prudich (Advisor) Subjects: Engineering, Chemical

Doctor of Philosophy, Case Western Reserve University, 1991, Macromolecular Science

Infrared spectroscopy was used to study the photooxidation of styrene-acrylonitrile (SAN) samples that were exposed to ultraviolet radiation having a minimum wavelength of 295 nm. It was determined that the photooxidation of SAN occurs exclusively at the styrene repeat units within the copolymer structure. The major infrared spectral changes resulting from the degradation process involve the appearance of new peaks within the hydroxyl and carbonyl regions. Using factor analysis results, it was concluded that there are a minimum of four different types of hydroxyl groups and three different types of carbonyl groups formed during the photooxidation of SAN. Furthermore, it was found that after 200 hours exposure the rate of increase in the concentration of the carbonyl groups within the degraded material is greater than the rate of increase in the concentration of the hydroxyl groups. The infrared spectra for a series of random styrene-acrylonitrile (SAN) copolymers of various compositions were then analyzed to determine the dependence of the individual spectral peaks on the copolymer composition. Correlations were established to relate changes in the peak positions and intensities to changes in the copolymer composition and monomer sequence distribution. A peak was assigned to a given microstructure if there existed a positive linear relationship between the peak intensity and the number fraction of this microstructure. These peak assignments were then applied to the photooxidation studies of SAN to determine the effect of the sequence distribution on the photooxidative process of the copolymer. Peaks at 1952, 1881, 912 and 549 cm-1 were found to have negative intensity values in the difference spectrum of photooxidized SAN. While the peaks at 1881 and 912 cm-1 had been assigned to the SAS triad structure, the peaks at 1952 and 549 cm-1 were assigned to the monad, dyad or triad structures of the styrene repeat unit. It was therefore concluded that the microstructure s (open full item for complete abstract)

Committee: Jack Koenig (Advisor) Subjects: