Doctor of Philosophy, University of Akron, 2023, Polymer Science

Plastic waste is causing environmental problems due to its accumulation on land and in the oceans. Recycling plastic is both economically and environmentally beneficial; however, there are limited options available for disposing of plastic waste. The problem of plastic waste is global and requires immediate attention. One of the major obstacles to plastic recycling is the difficulty in separating different types of plastics, such as polyethylene and polypropylene, which leads to an increase in plastic waste. Although these plastics have desirable properties, they are not compatible in their solid and melt states, making it difficult to reuse them. This issue occurs not only with polyolefin mixtures but also with most plastics. There are different approaches to achieve sustainable plastics, such as using compatibilizers, chemical cycling, advanced sorting, and creating new biodegradable and petroleum-based polymers. This study aims to develop novel petroleum-based polyolefins that possess a unique structure, comparable thermal as well as potentially mechanical properties to polyethylene (PE) and isotactic-polypropylene (iPP) and are capable of forming co-crystalline phases after secondary reuse, enhancing their potential for reusability. Co-crystallizing different semicrystalline polymers is a challenge, as each polymer has its own kinetics of crystallization, chain conformation and packing structures in the crystalline region. Even low-density polyethylene cannot fully co-crystallize with high- density polyethylene. So far, only a few systems, such as stereo-complexes like poly(lactic acid)s and poly(methyl methacrylate)s, have been able to co-crystallize. However, these require specific mixing ratios that are not feasible in secondary recycling. Very recently, Hayano and Nakama synthesized a series of unique polyolefins named as hydrogenated poly(norbornene) (hPNB)s with different stereoregularity showing semicrystalline features with a wide melting tempera (open full item for complete abstract)

Committee: Toshikazu Miyoshi (Advisor); Mesfin Tsige (Committee Chair); Ali Dhinojwala (Committee Member); Chunming Liu (Committee Member); James Eagan (Committee Member) Subjects: Materials Science; Physics; Plastics

Doctor of Philosophy, University of Akron, 2011, Polymer Science

Interfaces are important in many areas including adhesion, friction, coatings, nanocomposites, heat transfer, biomedical implants and cell biology. Most interfacial experiments involve force measurements and, consequently, molecular models to explain the force results. To make progress in this field, it is necessary to understand the structure of interfacial molecules in direct contact. Here, we have used the interface sensitivity of infrared-visible sum frequency generation spectroscopy (SFG) to probe the molecular structure of contact and sliding interfaces in-situ along with force measurements. SFG is a second order nonlinear optical technique that provides information on the chemical structure, orientation and concentration of molecules at interfaces. Two types of interfaces are probed in the current study. The initial two studies focus on static interfaces and the remaining three on dynamic interfaces. In the first investigation, we have studied polar interactions at solid-liquid and solid-solid interfaces using SFG spectroscopy. The shift of the sapphire surface hydroxyl peak in contact with several polar and non-polar liquids and polymers is used to determine the interaction energy. The trend in the interaction energies cannot be explained by only measuring water contact angles. Molecular rearrangements at the sapphire interface, to maximize the acid-base interactions, play a dominant role and these effects are not accounted for in the current theoretical models. The second investigation probes the interactions of polystyrene (PS)-poly(methyl methacrylate) (PMMA) blends with a sapphire surface. The acid-base interaction of carboxyl groups with surface hydroxyl groups is a strong driving force for segregation of PMMA next to the sapphire surface. Even with 0.005 weight fraction of PMMA in the blend, the concentration at the sapphire-blend interface is similar to that of bulk PMMA. This result is significant for understanding and controlling the interfaces res (open full item for complete abstract)

Committee: Ali Dhinojwala Dr. (Advisor); Mark Foster Dr. (Committee Chair); Gary Hamed Dr. (Committee Member); Alamgir Karim Dr. (Committee Member); Jutta Strathmann Dr. (Committee Member) Subjects: Materials Science; Physical Chemistry; Polymer Chemistry; Polymers

Doctor of Philosophy, University of Akron, 2007, Polymer Engineering

Poly(4-vinylphenol) (PVPh) was blended with four different polymers: poly(vinyl methyl ether) (PVME), poly(vinyl acetate) (PVAc), poly(2-vinylpyridine) (P2VP), and poly(4-vinylpyridine) (P4VP) by solvent casting. The miscibility of these four PVPh-based blend systems was investigated using differential scanning calorimetry (DSC) and the composition-dependent glass transition temperature (Tg) was predicted by a thermodynamic theory. The hydrogen bonds between phenolic group in PVPh and ether group, carbonyl group or pyridine group was confirmed by Fourier transform infrared (FTIR) spectroscopy. The fraction of hydrogen bonds was calculated by the Coleman-Graf-Painter association model. Linear dynamic viscoelasticity of four PVPh-based miscible polymer blends with hydrogen bonding was investigated. Emphasis was placed on investigating how the linear dynamic viscoelasticity of miscible polymer blends with specific interaction might be different from that of miscible polymer blends without specific interaction. We have found that an application of time-temperature superposition (TTS) to the PVPh-based miscible blends with intermolecular hydrogen bonding is warranted even when the difference in the component glass transition temperatures is as large as about 200 °C, while TTS fails for miscible polymer blends without specific interactions. On the basis of such an observation, we have concluded that hydrogen bonding suppressed concentration fluctuations in PVPh-based miscible blends. It has been found that both the intra-association (self-association) of the phenoxy hydroxyl groups in PVPh and inter-association (intermolecular interactions) between the constituent components have a profound influence on the frequency dependence of dynamic moduli in the terminal region of the PVPh-based miscible blend systems investigated. Hydrogenated functional polynorbornenes (HFPNBs) were synthesized and they were used to investigate the miscibility and rheology of HFPNB-based miscibl (open full item for complete abstract)

Committee: Chang Dae Han (Advisor) Subjects:

Doctor of Philosophy (Ph.D.), University of Dayton, 2025, Materials Engineering

This dissertation investigates the development and application of non-halogenated, phosphorus-based reactive flame retardants in epoxy resin systems, focusing on optimizing the balance between fire resistance, mechanical properties, ease of processing, and cost-efficiency. Traditional halogenated retardants, while effective, pose significant environmental risks, necessitating the exploration of safer alternatives. Chapter 1 discusses the challenges of enhancing fire resistance in epoxy resins without relying on halogenated compounds. It emphasizes the need for solutions that integrate seamlessly with epoxy matrices, maintaining or enhancing mechanical performance cost-effectively. This chapter underscores the significance of this research in modern material science, highlighting the need for materials that can resist rapid combustion and meet stringent fire safety standards while being economical and easy to process. Chapter 2 presents a literature review showing the state-of-the-art in reactive phosphorus-based retardants and their ability to improve fire resistance through multiple mechanisms. It also identifies existing gaps in achieving an optimal balance with mechanical properties. Chapter 3 details the testing of FR5, an amine-functionalized phosphorus hydrazide, noting its effectiveness in improving char formation and smoke reduction but its limited impact on peak heat release rates. This result indicates the need for further development or combinations with other retardant chemistries to enhance effectiveness. Chapter 4 explores the use of P-DGEBA, a phosphorus-modified epoxy monomer, in carbon fiber composites, revealing its ability to enhance the glass transition temperature and reduce heat release. However, further studies are needed to fully understand its impact on composite properties and processing. Chapter 5 investigates the effects of commercially available phosphorus-based flame retardants like Fyrol PMP and DOPO on blends of DGEBA epoxy (EP) w (open full item for complete abstract)

Committee: Donald Klosterman (Advisor); Elias Toubia (Committee Member); Christopher Muratore (Committee Member); Alexander Morgan (Committee Member) Subjects: Aerospace Materials; Chemical Engineering; Engineering; Materials Science

Doctor of Philosophy, The Ohio State University, 2024, Environmental Science

Historical and current anthropogenic activity combined with land turnovers and rampant vacancies have increased human exposure risk to contaminants. This exposure risk disproportionately affects lower income communities and can have detrimental impacts on human health, particularly children. A management solution is needed to address this widespread contamination of vacant lots. Additionally, federal and state regulators continue to lower residential soil Pb standards which will likely require new risk-based approaches to address urban soil Pb contamination. This dissertation examines three different amendment types (P amendments, Fe oxide containing amendments, and potassium permanganate (KMnO4)) for their ability to address urban Pb soil contamination and reduce human health exposure risk. Remediation strategies that can address both organic and inorganic pollutants are also needed. This is addressed in Chapter 3. This dissertation is written as a series of manuscripts to be submitted to the appropriate journals; this will be reflected by slight differences in formatting. In Chapter 1, readily available P sources (biosolids incinerator ash, poultry litter, biosolids compost, and triple super phosphate) of varying solubility were assessed as soil amendments to reduce Pb bioaccessibility and serve as an inexpensive remediation strategy for urban soil. Contaminated soil from Cleveland, OH was treated with the P soil amendments at a 1:5 Pb:P molar ratio and incubated for 3 months. A slurry analysis was also conducted to assess reduction in bioaccessible Pb independent of time. Pb bioaccessibility was evaluated using US EPA Method 1340 at pH 1.5 and the Physiologically Based Extraction Test (PBET). Treatments were largely found ineffective regardless of IVBA extraction method, incubation duration, slurry analyses, or P source. Method 1340 had one significant treatment (combined poultry litter and BIA) but only resulted in a 8% IVBA Pb reduction. The same treatmen (open full item for complete abstract)

Committee: Nicholas Basta (Advisor); Brian Lower (Committee Member); Steven Lower (Committee Member); Darryl Hood (Committee Member) Subjects: Environmental Science; Soil Sciences

Doctor of Philosophy, University of Akron, 2023, Polymer Science

Nanostructured hybrid materials can be formed using self-assembling side chains grafted to a polymer backbone. Small-angle X-ray and neutron scattering (SAXS & SANS) measurements on polyisobutylene graft copolymers with side chains containing β-alanine trimer have revealed that crystalline nanodomains form by self-assembly. Modifying the side chain chemistry allows one to tailor the β-alanine nanocrystal length from over 300nm down to approximately 10nm. The degree of crowding at the nanodomain interfaces impacts the temperature dependence of the microphase separation. Chemical variations in the side chains, such as removing C18 tails and adding C11 spacers between the backbone and β-alanine trimers have dramatic effects on nanocrystal size, domain spacings, order-disorder transition temperature and width of transition, crystal melting temperature, and bulk mechanical properties. The last chapter describes progress in defining the interface morphologies in blends modified with Interfacial Supramolecular Coupling Agents (ISCAs) containing β-alanine. Polyethylene (PE) and polypropylene (PP) constitute the majority of mixed plastic waste produced globally. In the approach studied, it is envisioned that a pair of ISCAs will populate the interfaces between PE-rich and PP-rich phases and anchor the phases together. From SAXS, SANS, Wide Angle X-ray Scattering (WAXS) and Atomic Force Microscopy (AFM) analysis it is evident that the presence of ISCAs alters the crystalline structure of the overall blend.

Committee: Mark Foster (Advisor); Mesfin Tsige (Committee Chair); Bi-min Zhang Newby (Committee Member); Toshikazu Miyoshi (Committee Member); Li Jia (Committee Member) Subjects: Engineering; Materials Science; Nanoscience; Nanotechnology; Physics

Doctor of Philosophy, University of Akron, 2023, Polymer Engineering

One-way shape memory polymers (SMPs) possess the unique ability to remember a programmed 'temporary shape' and revert to its original shape when exposed to an external stimulus. Typically, SMPs contain two structure-spanning, solid networks; a permanent elastic network that is strained during programming to drive shape recovery; and a temporary network that fixes the programmed shape. The shape-shifting features of SMPs make them useful for a wide range of potential applications, including 4D printing, soft robotics, flexible electronics, soft aeronautical engineering, and biomedical devices. An interesting pathway to develop SMPs is by blending an elastomer and a crystalline small molecule, where the elastomer forms the permanent network (that promotes shape recovery), and the small molecule crystal forms the temporary networks (that promotes shape fixity). Typical examples of these systems include crosslinked elastomers (natural rubber) swelled in fatty acids (lauric acid, stearic acid, and palmitic acid), straight-chain alkanes (eicosane, tetracosane) or synthetic waxes (paraffin wax). However, a drawback of this approach is the blooming and expulsion of the small molecule during shape programming and recovery. This dissertation attempts to focus on semi-crystalline shape memory elastomers developed from blends of high cis 1,4 polybutadiene and reactive monomers (octadecyl acrylate and benzyl methacrylate) or molecular crystals (n-eicosane and n-tetracosane) with the aim being reducing the effect of blooming while keeping a simple fabrication route to develop these SMPs. The synthetic, network, mechanical, thermal, and morphological properties of a series of polybutadiene-based semicrystalline or glassy blends were studied to understand the structureproperty relationships between their permanent and reversible networks. Furthermore, it will be shown that thermally annealed high cis 1,4 polybutadiene also demonstrates thermoresponsive actuatio (open full item for complete abstract)

Committee: Kevin Cavichhi (Advisor); Fardin Khabaz (Committee Chair); Qixin Zhou (Committee Member); Li Jia (Committee Member); Weinan Xu (Committee Member) Subjects: Chemistry; Materials Science; Plastics

Master of Science, University of Toledo, 2023, Chemical Engineering

In this work, the impact of the co-monomer, furan dicarboxylate (FDCA), on depolymerization of poly (ethylene terephthalate) (PET) was investigated. Specifically, glycolysis and alkaline hydrolysis were used to depolymerize the following polyesters: (i) PET, (ii) polyethylene furonate (PEF), (iii) a copolymer with 10 % FDCA and 90 % TPA (PETF10-I) and (iv) a melt blend of 10 % PEF and 90 % PET (PETF10-B). The alkaline hydrolysis kinetics were studied at 110 oC in 1.1 M sodium hydroxide (NaOH) solution [45, 46, 65]. Glycolysis kinetics were studied at 180 oC in ethylene glycol (EG) with a zinc acetate catalyst [31, 47, 66]. Both reactions occur at the surface of the polyester flakes so that surface wetting by the solution, surface area of flakes, and backbone structure of the polymer are important in determining reaction kinetics. In addition, this work showed that the polyester configuration played a role in depolymerization kinetics for the PET/PEF mixed systems. The PEF exhibited much faster rates of depolymerization for both hydrolysis and glycolysis than pure PET, which was attributed to the presence of five member rings that are more labile than benzene ring. The inclusion FDCA based polyesters as a co-polymer or blend resulted in increases in depolymerization rates relative to the PET. The blend exhibited faster rates of kinetics than the co-polyester indicating that the configuration or macrostructure was important in determining depolymerization kinetics. The more rapid kinetics of the blends was attributed to a combination of (i) improved surface wetting by the reaction media and (ii) high degradation rates for PEF in blends which generated small pits in surface and increased surface area. The hydrolysis product for both the blend and co-polymers of PETF10 contained FDCA and TPA. However, high purity of BHET was recovered from the reaction mixture with only traces of BHEF following glycolysis of the blends and co-polyester. While it was difficult to rec (open full item for complete abstract)

Committee: Maria Coleman (Committee Chair); Joseph Lawrence (Committee Member); Dong -Shik Kim (Committee Member) Subjects: Chemical Engineering

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

Doctor of Philosophy, Case Western Reserve University, 2020, Macromolecular Science and Engineering

Mixing different polymers is a well-known way to obtain distinct final properties that would not be obtainable with separate components. Researching efficient and exquisite ways to blend them into morphologies and tailor interfacial microstructure is desirable to construct multiphase materials with potentially functional interfaces. Janus particles or rigid surfactants are attractive for these purposes given their distinguished interfacial activity and self-assembly prospects. In Chapter 2, from aggregate structure, kinetics, and diffusivity arguments, the way that shorter or longer Janus rods assemble interfacially is shown to impact polymer blend phase separation. In Chapter 3, their colloidal tumbling behavior under interfacial shear flow is examined to search opportunities for self-assembly and original nanotechnological applications. Conspicuously, parallel or antiparallel Janus rod alignment at the interface, as well as stacked superlattice sheets, can be tuned according to rod concentration, shear rate, aggregate shape, and interaction potential intensity. Furthermore, an inquiry into slip and momentum transfer mechanisms across polymer-polymer interfaces follows in Chapter 4. For conditions that may ultimately favor the delay of polymeric droplet coalescence and stabilize polymeric emulsions, polymer-grafted Janus rods with longer grafts should be employed among flexible or other rigid surfactants. Additionally, their corresponding grafting density may serve the purpose of controlling interfacial aggregation. In Chapter 5, the reptational diffusive behavior of very long polymer chains is reproduced to show how accounting for entanglements among polymer chains allows for slower relaxation processes in Janus-rod stabilized immiscible polymer blends. These topological constraints that are added to polymer segments make for more realistic polymer motion and predict a more pronounced viscoelastic behavior. All these investigations on the interfacial behavior of J (open full item for complete abstract)

Committee: Joao Maia (Committee Chair); Veronica Calado (Advisor); Argimiro Secchi (Advisor); Shaghayegh Khani (Committee Member); Michael Hore (Committee Member); Gary Wnek (Committee Member); Daniel Lacks (Committee Member); Marcio Nele (Committee Member); Frederico Tavares (Committee Member) Subjects: Chemical Engineering; Engineering; Materials Science; Nanoscience; Nanotechnology; Polymers

Doctor of Philosophy, Case Western Reserve University, 2020, Macromolecular Science and Engineering

As society evolves and technology develops further, the need for more advanced products is increasing, so polymeric materials are gaining ever more attraction because of their excellent properties such as lightweight, low cost and good resistance to corrosion. Polymer processing is one of the keys to achieve these unique materials. Various kinds of morphologies can be produced during polymer melt compounding including droplet-matrix, fibrillar, lamellar, or co-continuous structures. Co-continuous morphology, which has the coexistence of two continuous structures within the same volume, has been drawing more attention currently because of its specific superior properties including a combination of the features of both components in a favorable way, as well as additional characteristics by selectively localizing fillers in the co-continuous structures. Since processing-structure-property relationships are guiding principles in materials design, development, and tailoring, it is important to study them in co-continuous polymer blends and composites. In chapter 1 of this dissertation, the formation and properties of co-continuous blends and double-percolated co-continuous composites are introduced. In chapter 2, the formation of co-continuous poly(ethylene) oxide/ethylene-vinyl acetate blends as well as the effects of structure and processing on their surface roughness are explored. Moreover, two thermally conductive co-continuous ternary composites systems are reported in chapter 3. The role of viscosity ratio on filler distribution and electrical/thermal properties of the carbon nanofiber reinforced co-continuous polymer composites is discussed, along with the discussion of the effects of filler sizes on morphology and thermal conductivity of double-percolated polypropylene/poly(methyl methacrylate)/boron nitride polymer composites. Furthermore, two additional projects are demonstrated in chapter 4 and chapter 5. Chapter 4 compares the fiber length distributi (open full item for complete abstract)

Committee: Joao Maia (Advisor); Ica Manas-Zloczower (Committee Member); Svetlana Morozova (Committee Member); Donald Feke (Committee Member) Subjects: Polymers

Doctor of Philosophy, Case Western Reserve University, 2020, Macromolecular Science and Engineering

The most widespread types of extruder are single-screw machines (SSE), which typically are poor mixing devices but allow for large throughputs, and intermeshing co-rotating twin-screw (Co-TSE), which are good mixing devices but are not able to yield as high throughputs as SSEs. The mixing action in Co-TSEs is usually imparted via sets of kneading blocks (KBs), which impose shear-dominated flows. Shear flows are energetically inefficient for dispersive mixing by comparison with extensional flows. Our group previously developed a new Extensional Mixing Element (EME), with dispersive mixing provided by extension-dominated flow through stationary hyperbolically contracting channels. This first prototype, which was designed to impart relatively mild extension on the melt, showed tremendous improvement in dispersive mixing by comparison with aggressive KB sections. Herein, the EME design is optimized by defining the maximum contraction ratio admissible and the biaxial concept is introduced. The EME concept is also extended to SSE to enhance their dispersive mixing. Experiments are performed on immiscible polymer blends (low-viscosity ratio and high-viscosity ratio) and nanocomposites on both SSE and TSE. Morphological results showed enhancement in dispersive mixing capability of SSE when equipped with EME and mainly comparable to conventional TSE, that is, with KB as mixing sections, if not as good as TSEs equipped with EMEs. Rheological and crystallinity studies are observed to be in line with the morphological analysis. Mechanical results also showed enhanced modulus when EME is used. We also compared computationally the performance of two SSE mixing sections with significant extensional flow components, the CRD mixer and the EME. Tapered slots in the CRD and hyperbolic contractions in the EME attempt to create extensional stresses. Our studies confirm that EMEs are a better dispersive mixer than the CRD mixer, as they impose more intense and uniformly distributed ex (open full item for complete abstract)

Committee: Joao Maia Dr. (Advisor); Joao Maia Dr. (Committee Chair); Ica Manas-Zloczower Dr. (Committee Member); Hatsuo Ishida Dr. (Committee Member); Donald Feke Dr. (Committee Member) Subjects: Engineering; Fluid Dynamics; Plastics; Polymers

Doctor of Philosophy, University of Akron, 2020, Polymer Engineering

Colors are ubiquitously present in nature and are used in several day-to-day applications such as paints, textiles, cosmetics and displays. Most of these colors are pigment-based and suffer from non-environment friendliness, toxicity and non-tunability. Structural colors have received significant attention as alternatives to degradation-prone pigment-based colors. Many non-iridescent (angle-independent) structural colors in nature are produced from porous bio-polymer nanostructures with multi-functional properties such as UV-protection and hydrophobicity. However, most bioinspired synthetic non-iridescent structural colors have been attained via self-assembly of colloids and 3D printing, but they suffer from poor adhesion and robustness. Non-iridescent structural colors in nature, on the other hand, are produced from quasi-ordered porous nanostructures and are thought to form by polymeric phase separation but have not yet been achieved artificially despite their advantages including scalability. The objective of this dissertation is to develop a polymeric phase-separation process that results in non-iridescent structural coloration. Here, we report, for the first time, fabrication of non-iridescent structural colors from porous polymers via temperature-induced phase-separation of compatibilized polymer blend films. By simply tuning the molecular parameters such as composition of the polymer blend (ϕ), the color of the films can be tuned from white to blue to transparent with underlying morphological transitions from a disordered to a quasi-ordered state. Control on brightness and color saturation can be achieved by tuning optical interfaces and structural order respectively at a molecular level without using any additives by tuning molecular weight of homopolymers and block co-polymer. Gradient non-iridescent structural colors were attained from films of differential thickness via tunable coffee ring effect. We further examined the absence of green and red c (open full item for complete abstract)

Committee: Alamgir Karim (Advisor); Matthew Shawkey (Advisor); Sadhan Jana (Committee Member); Xiong Gong (Committee Chair); Erol Sancaktar (Committee Member); Tianbo Liu (Committee Member) Subjects: Polymer Chemistry

Doctor of Philosophy, University of Akron, 2019, Polymer Engineering

Shape memory polymers (SMPs) are a type of material capable of indefinitely holding a deformed shape and recovering their original shape upon the application of an external stimulus, such as temperature. SMPs contain at least two networks consisting of a permanent crosslinked polymer matrix and a second reversible, shape fixing network. These networks could be chemically bonded in single chemistry systems such as block copolymers containing elastic and glassy or crystalline phases or be blended together through elastomer and crystalline small molecule mixtures. This dissertation primarily focuses on SMP blends derived from fatty acid-elastomer blends with the aim being to further simplify the fabrication of these materials. The mechanical, thermal, and morphological properties of a series of different blends, along with several styrenic block copolymers, were studied to understand the structure-property relationships between their permanent and reversible networks. In Chapter II, fatty acid swollen natural rubber shape memory polymers were investigated as a function of swelling extent, acid polarity, and applied deformation. The fatty acid-rubber systems demonstrate a 40-50 wt% effective fatty acid solid phase loading range where the fixity of a programmed shape remained > 95% while maintaining structural integrity. The strength of the crystalline fatty acid networks were determined through dynamic mechanical analysis (DMA) moduli measurements where, under large uniaxial deformations, the modulus of the fatty acid was found to increase compared to the unstrained material. This was consistent with preferential alignment of crystal platelets along the strain direction as determined by small angle X-ray scattering (SAXS) measurements. In Chapter III, SMP foams were fabricated by immersing a polyurethane foam inside stearic acid-isopropyl alcohol solutions of varying concentration. Samples were programmed using DMA or a compression press. It was determined that f (open full item for complete abstract)

Committee: Kevin Cavicchi (Advisor); Mukerrem Cakmak (Advisor); Li Jia (Committee Member); Jiang Zhe (Committee Member); Sadhan Jana (Committee Chair) Subjects: Polymers

Doctor of Philosophy, Case Western Reserve University, 2019, Macromolecular Science and Engineering

This work targeted to unveil the processing-structure-property relationships of four polymeric systems with diverse transport properties. The first and the second chapters concentrated on a through-pore membrane derived from polypropylene (PP) and polyamide 6 (Nylon 6) blends. The other three chapters discussed the adjustable gas barrier properties in regards to the morphologies of polymer blends and multilayer films. Among all the chapters, gas and liquid transport properties were proved as an effective identifier for the morphology. The change in transport phenomena was strongly correlated with the shift in the structure. In Chapter One and Chapter Two, porous membranes were produced from biaxial orientation of polymer blends comprising PP, Nylon 6, and polypropylene grafted maleic anhydride (PPgMA). During biaxial orientation, the continuous PP domains cavitated while the dispersed Nylon 6 domains remained rigid and spherical. The effect of blend composition on cavitation was analyzed and a ternary diagram generated to identify the composition range for through-pore formation. The membranes were found to have adjustable porosity up to 62% with nanoscale size pores. The membranes show very high filtration efficiency on separating 50 nm Latex microbeads from water suspensions. In Chapter Three, the compatibilization effect of linear low density polyethylene grafted maleic anhydride (LLDPEgMA) and high density polyethylene grafted maleic anhydride (HDPEgMA) on high density polyethylene (HDPE) /Nylon 6 blend system was investigated. HDPEgMA was identified as a better compatibilizer than LLDPEgMA for the HDPE/Nylon 6 blend system. In Chapter Four, multilayer films comprising polystyrene (PS)/polymethyl methacrylate (PMMA) and PS/polycaprolactone (PCL) alternating nanolayers with varied layer thickness were fabricated by multilayer coextrusion. The continuous layers started to break up into nanosheets and nanodroplets during the coextrusion process when the no (open full item for complete abstract)

Committee: Eric Baer (Committee Chair); Andrew Olah (Committee Member); David Schiraldi (Committee Member); Ya-Ting Liao (Committee Member) Subjects: Chemical Engineering; Materials Science; Packaging; Plastics; Polymers

PhD, University of Cincinnati, 2018, Engineering and Applied Science: Biomedical Engineering

Myelomeningocele (MMC) is a neurologic defect characterized by failure of neural tube closure in the spinal column. This leads to cerebrospinal fluid leakage or contact with amniotic fluid, which can translate into sexual dysfunctions and paralysis after birth. The recently developed minimally-invasive technique for MMC repair is called fetoscopy, which involves a surgical patch, expanded for defect coverage on the fetus' back. Currently used inert patches do not degrade after implantation, necessitating a post-natal removal surgery, while collagen-based patches employed in are associated with poor mechanical integrity. Also, these patches are not tailored for fetoscopic MMC repair, and their response in fetal environment is unexplored. Deployment and expansion of coiled patch using surgical tools at defect site is time-consuming and cumbersome. Some of these existing patches have mesh-like structure for tissue in-growth, which makes their barrier properties debatable. Upon implantation at defect site, the patch encounters amniotic fluid and body fluids, as well as fluid forces due to fetal movement in the womb. This necessitates analysis of biodegradability and mechanical response of the patch for its adaptability in fetoscopic MMC repair. Taking the above requirements into consideration, we designed a patch comprising a blend of poly (L-lactic acid) (PLA) and poly (ε-caprolactone) (PCL), both polymers approved by the U.S. Food and Drug Administration for hard and soft tissue repair in spine. Different PLA-PCL formulations were characterized for surface and thermal properties, and the ideal formulation was chosen as our designed patch based on aptitude for thermal expansion at in-vivo temperature (37°C). This will enable self-expansion of the coiled patch at defect site, saving time and reducing difficulty level of surgery. The designed patch was characterized for barrier properties to ensure its watertight nature, and for biocompatibility after exposure to huma (open full item for complete abstract)

Committee: Chia-Ying Lin Ph.D. (Committee Chair); Yoonjee Park Ph.D. (Committee Member); Jose Peiro (Committee Member); Marepalli Rao Ph.D. (Committee Member) Subjects: Biomedical Research

Master of Science, The Ohio State University, 2017, Environment and Natural Resources

Soil quality has been defined by Doran and Parkin (1996) as the capacity of a soil to function within ecosystem boundaries to sustain biological productivity, maintain environmental quality, and promote plant and animal health. A multitude of physical, chemical, and biological parameters can be assessed to provide a comprehensive picture of soil quality. The overall objective of this study was to evaluate long term soil restoration and development of manufactured soil dredge blends by using these soil quality parameters. Chapter 1 assessed the soil quality of an urban site treated with biosolids or compost by comparing data collected over years of sampling after one initial application of the treatments. The results show that biosolids-based treatments leads to overall greater long-term soil quality than compost treatments. However, soil phosphorus in the biosolids-treated soils were of concern for runoff and surface water quality harm. Therefore, the study concludes that no treatment was the ideal amendment for overall improved soil quality, and that a blend of compost and biosolids together could be of interest in future research. In Chapter 2, soil quality parameters were used to assess dredge as a main ingredient in manufactured soil blends. With Ohio regulation changing how dredge must be disposed of, research into the beneficial reuse of soil-like dredge material is vital. Blends were designed by incorporating dredge materials, composts and clay then followed by a bioassay growing rye grass. Interestingly, the smaller size fraction dredge material, which is believed to be unsuitable for reuse, resulted in greater soil quality for the majority of the parameters. The addition of a compost material improved the blends, while clay and fertilizer additions did not result in greater soil quality or plant yield. Dredge showed to be a suitable material in manufactured soil blends for beneficial reuse.

Committee: Nicholas Basta PhD (Advisor); Brian Slater PhD (Committee Member); G. Matthew Davies PhD (Committee Member) Subjects: Environmental Science; Environmental Studies; Soil Sciences

Doctor of Philosophy, The Ohio State University, 2016, Environment and Natural Resources

Management of soil hazards in urban areas requires strategies that are scientifically effective and accepted by both the general public and public health regulators. Soil management options must consider all three of these components during evaluation. The concept of managing soil hazards to reduce contaminant exposure must be expanded to include considerations of soil function and soil health following remediation. Bioavailability assessments must be included with soil hazard assessments to improve hazard characterization. Soil hazard and soil health indicators can be combined in a comprehensive index, though the relative importance of each factor within the index will be site specific. Several recent studies have quantified contaminants in soil, such as lead (Pb), arsenic (As), and polycyclic aromatic hydrocarbons (PAHs), in many urban areas. When these findings are coupled with slow regulatory movement on potential management strategies, the public's perceived risk for potential exposure may increase. Such scenarios across the United States may reduce public support for widespread contaminant cleanup. Innovative interdisciplinary research initiatives are needed to: (1) evaluate potential contaminants and factors that contribute to healthy, functioning soil, (2) facilitate public and regulatory acceptance of potential soil hazards and treatments, and (3) communicate the public health implications of viable cleanup activities. These studies are particularly needed in vulnerable urban areas that demonstrate variable soil contaminant concentrations over small geographic spaces. Characterizing and addressing these soil contaminants will contribute to and benefit our society from public health, social, environmental, and economic perspectives. Soil contaminants and their impacts can be evaluated within the context of other exposures and individual characteristics, such as proposed in the developing field of exposome public health research. The results from this diss (open full item for complete abstract)

Committee: Nicholas Basta PhD. (Advisor); Steven Culman PhD. (Committee Member); Darryl Hood PhD. (Committee Member); Robyn Wilson PhD. (Committee Member) Subjects: Environmental Health; Environmental Management; Environmental Science; Environmental Studies; Public Health; Soil Sciences

Doctor of Philosophy, University of Akron, 2013, Chemistry

Semiflexible polymers of sufficient stiffness exhibit liquid crystalline order at low temperature and high polymer concentration. Blends of liquid crystalline and flexible polymers have interesting physical properties and important applications in organic electronics. We investigate melts and blends of flexible and semiflexible polymers with the aid of Monte Carlo simulations of an extension of Shaffer's bond-fluctuation model. To control chain stiffness we include a bending term in the Hamiltonian and investigate two models for semiflexibility that differ in the range of penalized bond angles. A study of structural, dynamic and thermodynamic properties of the first model shows that it describes melts of semiflexible chains that do not undergo a transition to a liquid crystalline state. Simulations of the second model reveal orientational order without positional order at high density and low temperature. The transition from the isotropic high-temperature phase to the nematic low-temperature phase, the IN transition, is accompanied by discontinuous changes in structural and thermodynamic properties. This agrees with mean-field theories and experimental observation that show that the IN transition is a discontinuous transition. To characterize our system fully, we determine the phase diagram and find that the IN transition temperature increases with increasing filling fraction, which agrees qualitatively with predictions by Onsager and Flory. Since pair distribution functions give insight into structure and morphology of polymers, we construct same-chain and different-chain distributions that we further differentiate by flexible and rod-like chain conformations. A study of same-chain pair distributions shows that the rod-like chains in our model align with a face diagonal in the nematic phase. Results for different-chain pair distribution functions show that a melt phase separates into a dense ordered region and a low-density disordered region when undergoing t (open full item for complete abstract)

Committee: Jutta Luettmer-Strathmann Dr. (Advisor); David Perry Dr. (Committee Member); Alper Buldum Dr. (Committee Member); David Modarelli Dr. (Committee Member); Kevin Cavicchi Dr. (Committee Member) Subjects: Chemistry; Physics; Polymers

Master of Science in Civil Engineering, University of Toledo, 2010, Civil Engineering

The main objective of this experimental thesis is to study the exhaust emissions of in-use garbage trucks for different idling modes fuelled with alternate fuels. The emission concentrations of carbon monoxide, sulfur dioxide, oxides of nitrogen (NO, NO2, and NOX), and carbon dioxide were examined with respect to engine parameters such as fuel temperature, coolant temperature and percent fuel. A Testo350 XL portable emission monitoring instrument was used to collect second by second data for the pollutants. Performance of engine parameters was also monitored simultaneously using on-board diagnostic (OBD) software. The tail pipe emissions from Ultra-Low Sulfur Diesel (ULSD) are compared with emissions from biodiesel blends. Hotter engines produced lower emissions compared to colder engines for all fuel blends and vehicle makes. Significant reductions in emission concentrations were observed due to the inspection and maintenance programs. The performance of biodiesel blends in reducing emission concentrations of pollutants across different vehicle makes was found to be inconsistent. A comprehensive study on various vehicle, fuel and operating parameters that effect the exhaust emission concentrations was conducted to find an alternative to ULSD.

Committee: Ashok Kumar PhD (Committee Chair); Brian Randolph PhD (Committee Member); Dong-Shik Kim PhD (Committee Member) Subjects: Alternative Energy; Automotive Engineering; Civil Engineering; Environmental Engineering; Environmental Health; Environmental Science; Environmental Studies; Experiments; Sustainability; Transportation; Urban Planning