Master of Science, Miami University, 2002, Paper Science and Engineering

The objective of this work was to explore the feasibility of generating a fiber-latex-TiO 2 -composite material that could be used as an additive in the papermachine wet end. By initially binding a cationic latex and subsequently anionic TiO 2 to the fiber surface and then curing the latex, it was envisioned that the pigment would be strongly retained in a latex film on the fiber surface. This novel additive could be utilized in papermaking operations achieving high TiO 2 retention and substantial cost-savings. Dispersion turbidity and microscopy were used to monitor experiments. Data were generated on the interaction between fiber and cationic latex, and a fiber-latex intermediate and TiO 2 . Retention levels of TiO 2 in the range of the target value were achieved, and stability tests proved the material resistant to normal pH and shear stresses. However, the cured composite proved difficult to redisperse and a different approach for curing must be explored.

Committee: William Scott (Advisor) Subjects: Engineering, Materials Science

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

Since there is a complementary effect between the performance of polyurethane and polyacrylate, the modification of acrylate with urethane is gaining increasing interest. The utilization of urethane methacrylate monomers has been found to be a promising solution for addressing compatibility issues and improving film properties. Significant efforts have been invested into the investigation of urethane methacrylates with linear alkyl terminal groups in acrylic latexes in Soucek group. The present work aims to bridge the knowledge gap regarding the impact of urethane methacrylates monomers with bulky (cyclic and branched) alkyl terminal groups and to investigate the self-healing potential of urethane/acrylate hybrid latexes incorporating the urethane methacrylate monomers. In Chapters III-IV, two urethane methacrylates, one containing a cyclohexyl terminal group and the other with a tert-butyl terminal group, were designed, synthesized, characterized, and incorporated into a series of homogeneous and core-shell hybrid latexes at various concentrations. The resulting hybrid latexes and their films were evaluated in terms of film formation ability, thermal properties, viscoelastic and mechanical properties, and hydrogen bond analysis. Urethane methacrylates with bulky terminal groups contributed to the enhanced film formation ability and film mechanical strength. The terminal group bulkiness appeared to exert a more pronounced effect on the film stiffness, in comparison to the hydrogen bonding. In Chapter IV, the self-healing potential of latex film containing the urethane methacylate with a tert-butyl terminal group was also studied. The introduction of urethane functionality led to more efficient healing performance. In Chapter V, a series of hydrogen bond-based self-healing acrylic latexes were developed by emulsion polymerization. The hydrogen bonding was introduced by the urethane group of a urethane methacrylate with a methyl terminal group and the hydroxyl group (open full item for complete abstract)

Committee: Mark Soucek (Advisor); Weinan Xu (Committee Chair); Kevin Cavicchi (Committee Member); Junpeng Wang (Committee Member); Jie Zheng (Committee Member) Subjects: Chemistry; Materials Science

Bachelor of Science (BS), Ohio University, 2021, Computer Science

There is a strong desire to be able to more easily formalize existing mathematical statements and develop machine-checked proofs to verify their validity. Doing this by hand can be a painstaking process with a steep learning curve. In this paper, we propose a model that could automatically parse natural language proofs written in LaTeX into the language of the interactive theorem prover, Coq, using a recurrent neural network. We aim to show the ability for such a model to work well within a very limited domain of proofs about even and odd expressions and exhibit generalization at test time. We demonstrate the model's ability to generalize well given small variations in natural language and even demonstrate early promising results for the model to generalize to expressions of intermediate lengths unseen at training time.

Committee: David Juedes (Advisor) Subjects: Computer Science

Doctor of Philosophy, University of Akron, 2020, Engineering-Applied Mathematics

A model is developed for predicting long-wavelength film thickness nonuniformities in drying latex paint films. After applying the lubrication approximation to the model equations, both linear and nonlinear stability analyses are performed. For the linear stability analysis, spatially independent base state solutions are found. These equations are solved numerically and a linear stability analysis of these base state solutions is conducted. In this case, the base state solution of the height represents a uniformly drying latex paint film with respect to time. For the nonlinear stability analysis, the leading order equations are solved numerically. The stability of the film is dependent on temperature, latex particle volume fraction, titanium dioxide particle volume fraction, extender particle volume fraction, surface surfactant density, bulk surfactant density, and several material and environmental factors. Slow evaporation, temperature gradients, surfactant desorption, surface tension gradients, low initial surface tension are identified as destabilizing mechanisms while fast evaporation, fast surfactant adsorption, high initial surface tension, high particle volume fractions, and viscosity are identified as stabilizing mechanisms.

Committee: Patrick Wilber (Advisor); Kevin Kreider (Committee Member); Curtis Clemons (Committee Member); George Chase (Committee Member); Qixin Zhou (Committee Member); Ali Dhinojwala (Committee Member) Subjects: Applied Mathematics; Chemical Engineering

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

In this study, secondary nucleation in latexes prepared by emulsion copolymerization of butyl acrylate (BA), styrene (St) and 2-hydroxyethyl methacrylate (HEMA), was investigated. The main purpose is to study the effect of monomer hydrophobicity on secondary nucleation. Monomer hydrophobicity was determined by different molar ratios of BA and St in monomer emulsion feed composition. Average particle size, particle size distribution (PSD), polymerization kinetics, glass transition temperature (Tg), and surface tension were monitored and compared. All synthetic latexes were prepared through seeded semi-batch emulsion polymerization. Three different BA to St ratios (BA:St=1:1, BA:St=1:2, BA:St=2:1) combined with five different HEMA content (0, 10, 20, 30, 40 mol%) in monomer composition respectively, were first prepared and characterized. Dynamic light scattering (DLS) was used to obtain average particle size and PSD while transmission electron microscopy (TEM) served as a supplemental independent characterization method to verify DLS results. Instantaneous conversion and overall conversion were monitored gravimetrically for kinetics study. Differential scanning calorimeter (DSC) was used to measure Tg. Surface tension was obtained using tensionmeter. It was found that increasing HEMA content to 10 mol% leads to secondary nucleation via proposed homogeneous nucleation of HEMA-rich oligo-radicals regardless of BA to St ratio. Further, in order to study the potential effect of the BA to St ratio on the critical HEMA content that triggers secondary nucleation in BA/St/HEMA latexes, the same three latex series with low HEMA content (1, 3, 5 mol%), were prepared and characterized following the same procedure. In the case of low HEMA content, the BA to St ratio significantly affects the critical HEMA content.

Committee: Mark D. Soucek (Advisor); Sadhan C. Jana (Committee Member); Ruel McKenzie (Committee Member) Subjects: Polymer Chemistry; Polymers

Master of Science, University of Akron, 2016, Applied Mathematics

A model is developed for predicting the long range length scale of film thickness nonuniformities in drying latex paint films. After applying the lubrication approximation to the model equations, spatially independent base state solutions are found. These equations are solved numerically and a linear stability analysis of these base state solutions is conducted. In this case, the base state solution of the height represents a uniformly drying latex paint film with respect to time. The stability of the film is dependent on temperature, latex particle volume fraction, surface surfactant density, bulk surfactant density, and several material and environmental factors. Evaporation, slow and equal surfactant kinetics, low initial surface tension, substrate permeability and high initial latex particle volume fractions are identified as destabilizing mechanisms while fast surfactant kinetics, high initial surface tension and viscosity are identified as stabilizing mechanisms.

Committee: Patrick Wilber Dr. (Advisor); Curtis Clemons Dr. (Committee Member); Kevin Kreider Dr. (Committee Member) Subjects: Applied Mathematics; Chemical Engineering; Chemistry; Engineering; Fluid Dynamics; Mathematics

Master of Science in Computer Engineering (MSCE), Wright State University, 2008, Computer Engineering

Preparation of academic papers involves not only the creative processes but also the more mechanical tasks such as adjusting the form and style to suit the demands of the publishing journal or conference. Among several packages that help in these rather tedious mechanical tasks, the TEX + LATEX + BibTEX combination is extremely popular. This thesis is about tools that help in the necessary task of citing related work accurately. It focuses on three aspects of this larger bibliography frame work: (i) a survey of existing bibliography formats and tools, (ii) a database view of BibTEX files and functionality that ensues, and (iii) processing references given as free style pieces of text. Numerous tools that ease the citation task have been developed in the last five years. The thesis reviews thoroughly the 65 open source, and freeware tools, and somewhat less thoroughly the 18 commercial tools because of limitations of trial ware. These tools range from small stand-alone utilities of a couple of thousand lines of code to large suites of tools that evolved out of the research work of teams over a few years. Their functionality includes the collection of references and searching the various on-line bibliographies for full details and prepare them for inclusion in the references section typically found at the end of papers. We identify a few voids in functionality, especially dealing with free style references, and contribute new tools. The second focus of the thesis is on the maintenance of bibliographies by individuals. In this context, we contribute several new tools: (i) LoadBibTeX stores bibliographic entries as a MySQL database of BibTEX fields as tables as opposed to storing them as plain text .bib files. (ii) BibSearch allows authors to search the database of BibTEX entries based on multiple keywords that can be matched in multiple fields and the resulting output may be saved as a standard .bib file. (iii) Normalization is a feature incorporated into the above too (open full item for complete abstract)

Committee: Prabhaker Mateti (Advisor) Subjects: Computer Science

Master of Science (MS), Ohio University, 1998, Electrical Engineering & Computer Science (Engineering and Technology)

Browser evolution: Document access on the world wide web

Committee: Shawn Ostermann (Advisor) Subjects:

Doctor of Philosophy, University of Akron, 2009, Polymer Science

Scanning probe microscopies (SPMs) allow the observation and measurement of surface properties on a highly local level based on the interaction between a very sharp probe and the surface. Interaction stability and probe integrity, at least during the scanning time, are necessary, but still a challenge. Conventional scanning probes have been used for revealing morphological features connected with macroscopic properties of complex latex films. These films, when dry, are sufficiently hard to be studied with minimal distortion of the surface by the probe. By comparing formulations with various fluorosurfactant concentrations, it was demonstrated how the fluorosurfactant, which is known heuristically to improve leveling, gives the system more mobility before drying. Specifically, in styrene-butadiene copolymer formulations, sub-micrometer differences in surface morphology, observed as a function of fluorosurfactant concentration, correlated with differences in gloss. In some cases, surfaces are too soft or too adhesive to be studied by conventional probes. Modification of scanning probes with hydrophobic layers having methyl or fluorinated end groups has been used to weaken the probe-surface interaction to study model adhesive surfaces. Acrylic block copolymers with well-defined molecular weight and composition were synthesized by controlled radical polymerization to create models of pressure sensitive adhesives to evaluate performance after aging or humidity exposure.Macroscopically, tack measurements demonstrated that blending a triblock copolymer with a homopolymer of the midblock polymer can be used to tailor the tack value. Microscopically, force-penetration curves of the acrylic blends showed a superficial phase separation into two mixed phases as homopolymer content was increased. Hydrophobic modification made it possible to measure these surfaces that would otherwise be too adhesive to study with conventional probes. Modification of scanning probes has also be (open full item for complete abstract)

Committee: Mark Foster (Advisor) Subjects: Analytical Chemistry; Materials Science; Optics; Physics; Polymers

Doctor of Philosophy, University of Akron, 2009, Polymer Engineering

Hydrophilic or hydrophobic functional monomers impart unusual properties to latexes. The type, amount, and addition sequence of functional monomers affect the colloidal stability, film formation and mechanical properties of latexes. Carboxylic acid and hydroxyl functional monomers provide reactive sites for crosslinking. The colloidal stability of latex particles can be enhanced by functional groups such as carboxylic acids. The latexes with functional groups can also be used to graft inorganic materials to form hybrid materials. Functional groups on the latexes not only determine the morphology of the latexes, but also the polymerization kinetics. The present work focused on assessing the effects of the type and the amount of functional monomers on the physical properties of hybrid latexes (particle size, solid content, and glass transition temperature, etc.), polymerization kinetics of core-shell latexes and mechanical properties of thermoset latex films. The first aim was to investigate the effect of hydrophobic groups such as polysiloxane on the physical properties of latexes. Polysiloxane-functionalized acrylic latexes were prepared by three different grafting techniques. In the first method, an acrylic core was prepared with the addition of a coupling agent, 3-(trimethoxysilyl) propyl methacrylate, after which a cyclic siloxane monomer (octamethylcyclotetra-siloxane, D4) was grafted onto the coupling agent. In the second method, a methacrylate- terminated polysiloxane was copolymerized with ethyl acrylate (EA) and 2-ethylhexyl acrylate (EHA) in batch emulsion polymerization. In the third method, D4 was added during emulsion polymerization of EA, EHA and 2-hydroxyethyl methacrylate. A core-shell morphology was observed in transmission electron microscopy (TEM) for the first preparation method. Microphase separation was observed by atomic force microscopy (AFM) after polysiloxane-functionalization for all latex films. Energy dispersive X-ray data indicated that (open full item for complete abstract)

Committee: Mark Soucek (Committee Chair) Subjects: Polymers