Matching Items (7)

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Shape factors for the pseudo-steady state flow in fractured hydrocarbon wells of various drainage area geometries

Description

Pseudo-steady state (PSS) flow is an important time-dependent flow regime that

quickly follows the initial transient flow regime in the constant-rate production of

a closed boundary hydrocarbon reservoir. The characterization of the

Pseudo-steady state (PSS) flow is an important time-dependent flow regime that

quickly follows the initial transient flow regime in the constant-rate production of

a closed boundary hydrocarbon reservoir. The characterization of the PSS flow

regime is of importance in describing the reservoir pressure distribution as well as the

productivity index (PI) of the flow regime. The PI describes the production potential

of the well and is often used in fracture optimization and production-rate decline

analysis. In 2016, Chen determined the exact analytical solution for PSS flow of a

fully penetrated vertically fractured well with finite fracture conductivity for reservoirs

of elliptical shape. The present work aimed to expand Chen’s exact analytical solution

to commonly encountered reservoirs geometries including rectangular, rhomboid,

and triangular by introducing respective shape factors generated from extensive

computational modeling studies based on an identical drainage area assumption. The

aforementioned shape factors were generated and characterized as functions for use

in spreadsheet calculations as well as graphical format for simplistic in-field look-up

use. Demonstrative use of the shape factors for over 20 additional simulations showed

high fidelity of the shape factor to accurately predict (mean average percentage error

remained under 1.5 %) the true PSS constant by modulating Chen’s solution for

elliptical reservoirs. The methodology of the shape factor generation lays the ground

work for more extensive and specific shape factors to be generated for cases such as

non-concentric wells and other geometries not studied.

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Date Created
  • 2017

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Mechanically active heterogeneous polymer matrix composites

Description

An evolving understanding of elastomeric polymer nanocomposites continues to expand commercial, defense, and industrial products and applications. This work explores the thermomechanical properties of elastomeric nanocomposites prepared from bisphenol A

An evolving understanding of elastomeric polymer nanocomposites continues to expand commercial, defense, and industrial products and applications. This work explores the thermomechanical properties of elastomeric nanocomposites prepared from bisphenol A diglycidyl ether (BADGE) and three amine-terminated poly(propylene oxides) (Jeffamines). The Jeffamines investigated include difunctional crosslinkers with molecular weights of 2,000 and 4,000 g/mol and a trifunctional crosslinker with a molecular weight of 3,000 g/mol. Additionally, carbon nanotubes (CNTs) were added, up to 1.25 wt%, to each thermoset. The findings indicate that the Tg and storage modulus of the polymer nanocomposites can be controlled independently within narrow concentration windows, and that effects observed following CNT incorporation are dependent on the crosslinker molecular weight.

Polymer matrix composites (PMCs) offer design solutions to produce smart sensing, conductive, or high performance composites for a number of critical applications. Nanoparticle additives, in particular, carbon nanotubes and metallic quantum dots, have been investigated for their ability to improve the conductivity, thermal stability, and mechanical strength of traditional composites. Herein we report the use of quantum dots (QDs) and fluorescently labeled carbon nanotubes (CNTs) to modify the thermomechanical properties of PMCs. Additionally, we find that pronounced changes in fluorescence emerge following plastic deformation, indicating that in these polymeric materials the transduction of mechanical force into the fluorescence occurs in response to mechanical activation.

Segmented ionenes are a class of thermoplastic elastomers that contain a permanent charged group within the polymer backbone and a spacer segment with a low glass transition temperature (Tg) to provide flexibility. Ionenes are of interest because of their synthetic versatility, unique morphologies, and ionic nature. Using phase changing ionene-based nanocomposites could be extended to create reversible mechanically, electrically, optically, and/or thermally responsive materials depending on constituent nanoparticles and polymers. This talk will discuss recent efforts to utilize the synthetic versatility of ionenes (e.g., spacer composition of PTMO or PEG) to prepare percolated ionic domains in microphase separated polymers that display a range of thermomechanical properties. Furthermore, by synthesizing two series of ionene copolymers with either PEG or PTMO spacers at various ratios with 1,12-dibromododecane will yield a range of ion contents (hard contents) and will impact nanoparticle dispersion.

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Date Created
  • 2019

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Analysis of Chlorination & UV Effects on Microplastics Using Raman Spectroscopy.

Description

Microplastics are emerging to be major problem when it comes to water pollution and they pose a great threat to marine life. These materials have the potential to affect a

Microplastics are emerging to be major problem when it comes to water pollution and they pose a great threat to marine life. These materials have the potential to affect a wide range of human population since humans are the major consumers of marine organisms. Microplastics are less than 5 mm in diameter, and can escape from traditional wastewater treatment plant (WWTP) processes and end up in our water sources. Due to their small size, they have a large surface area and can react with chlorine, which it encounters in the final stages of WWTP. After the microplastics accumulate in various bodies of water, they are exposed to sunlight, which contains oxidative ultraviolet (UV) light. Since the microplastics are exposed to oxidants during and after the treatment, there is a strong chance that they will undergo chemical and/or physical changes. The WWTP conditions were replicated in the lab by varying the concentrations of chlorine from 70 to 100 mg/L in increments of 10 mg/L and incubating the samples in chlorine baths for 1–9 days. The chlorinated samples were tested for any structural changes using Raman spectroscopy. High density polyethylene (HDPE), polystyrene (PS), and polypropylene (PP) were treated in chlorine baths and observed for Raman intensity variations, Raman peak shifts, and the formation of new peaks over different exposure times. HDPE responded with a lot of oxidation peaks and shifts of peaks after just one day. For the degradation of semi-crystalline polymers, there was a reduction in crystallinity, as verified by thermal analysis. There was a decrease in the enthalpy of melting as well as the melting temperature with an increase in the exposure time or chlorine concentration, which pointed at the degradation of plastics and bond cleavages. To test the plastic response to

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UV, the samples were exposed to sunlight for up to 210 days and analyzed under Raman spectroscopy. Overall the physical and chemical changes with the polymers are evident and makes a way for the wastewater treatment plant to take necessary steps to capture the microplastics to avoid the release of any kind of degraded microplastics that could affect marine life and the environment.

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Date Created
  • 2017

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Synthesis of Two-Dimensional Metal-Organic Frameworks and their Alloys

Description

Metal-organic frameworks have made a feature in the cutting-edge technology with a wide variety of applications because they are the new material candidate as adsorbent or membrane with high surface

Metal-organic frameworks have made a feature in the cutting-edge technology with a wide variety of applications because they are the new material candidate as adsorbent or membrane with high surface area, various pore sizes, and highly tunable framework functionality properties. The emergence of two-dimensional (2D) metal-organic frameworks has surged an outburst of intense research to understand the feasible synthesis and exciting material properties of these class of materials. Despite their potential, studies to date show that it is extremely challenging to synthesize and manufacture 2D MOF at large scales with ultimate control over crystallinity and thickness.

The field of research to date has produced various synthesis routes which can further be used to design 2D materials with a range of organic ligands and metal linkers. This thesis seeks to extend these design rules to demonstrate the competitive growth of two- dimensional (2D) metal-organic frameworks(MOF) and their alloys to predict which ligands and metals can be combined, study the intercalation of Bromine in these frameworks and their alloys which leads to the discovery of reduced band gap in the layered MOF alloy.

In this study it has been shown that the key factor in achieving layered 2D MOFs and it relies on the use of carefully engineered ligands to terminate the out-of-plane sites on metal clusters thereby eliminating strong interlayer hydrogen bond formation.

The major contribution of pyridine is to replace interlayer hydrogen bonding or other weak chemical bonds. Overall results establish an entirely new synthesis method for producing highly crystalline and scalable 2D MOFs and their alloys. Bromine intercalation merits future studies on band gap engineering in these layered materials.

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Date Created
  • 2020

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Zwitterionic poly (arylene ether sulfone) copolymers: membrane applications and fundamentals

Description

Zwitterionic polymers, due to their supurior capability of electrostatically induced hydration, have been considered as effective functionalities to alleviate bio-fouling of reverse osmosis (RO) membranes. Bulk modification of polysulfone-based matrices

Zwitterionic polymers, due to their supurior capability of electrostatically induced hydration, have been considered as effective functionalities to alleviate bio-fouling of reverse osmosis (RO) membranes. Bulk modification of polysulfone-based matrices to improve hydrophilicity, on the other hand, is favored due to the high membrane performance, processibility, and intrinsic chlorine resistance. Here a novel synthetic method was demonstrated to prepare zwitterionic poly(arylene ether sulfone) (PAES) copolymers, which was blended with native polysulfone (PSf) to fabricate free-standing asymmetric membranes via non-solvent induced phase separation process. Both the porosity of the support layer and surface hydrophilicity increased drastically due to the incorporation of zwitterion functionalities in the rigid polysulfone matrix. The water permeance and antifouling ability of the blend membranes were both remarkably improved to 2.5 Lm−2 h−1 bar−1 and 94% of flux recovery ratio, respectively, while salt rejection remained at a high level (98%) even under the high exposure to chlorine (8,000 ppm•h). Besides the preliminary blended membrane design, for the future membrane property enhancement, this dissertation also focused on polymer structure optimizations via elucidating the fundamentals from two perspectives: 1). Synthetic reaction kinetics and mechanisms on polycondensation of PAES. Interestingly, in combination of experiments and the computational calculations by density functional theory (DFT) methods in this work, only the aryl chlorides (ArCl) monomer follows the classical second-order reaction kinetics of aromatic nucleophilic substitution (SNAr) mechanism, while the kinetics of the aryl fluorides (ArF) reaction fit a third-order rate law. The third order reaction behavior of the ArF monomer is attributed to the activation of the carbon-fluorine bond by two potassium cations (at least one bounded to phenolate), which associate as a strong three-body complex. This complex acts as the predominant reactant during the attack by the nucleophile. 2). Optimized copolymer structures were developed for controlled high molecular weight (Mw ~ 65 kDa) and zwitterionic charge content (0~100 mol%), via off-set stoichiometry during polycondensations, following with thiol-ene click reaction and ring-opening of sultone to introduce the sulfobetaine functional groups. The structure-property-morphology relationships were elucidated for better understanding atomic-level features in the charged polymers for future high-performance desalination applications.

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Date Created
  • 2019

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Synthesis of Acetylenic Carbon Molecules via Pulsed Laser Ablation in Ethanol

Description

New forms of carbon are being discovered at a rapid rate and prove to be on the frontier of cutting edge technology. Carbon possesses three energetically competitive forms of orbital

New forms of carbon are being discovered at a rapid rate and prove to be on the frontier of cutting edge technology. Carbon possesses three energetically competitive forms of orbital hybridization, leading to exceptional blends of properties unseen in other materials. Fascinating properties found among carbon allotropes, such as, fullerenes, carbon nanotubes, and graphene have led to new and exciting advancement, with recent applications in defense, energy storage, construction, and electronics. Various combinations of extreme strength, high electrical and thermal conductivity, flexibility, and light weight have led to new durable and flexible display screens, optoelectronics, quantum computing, and strength enhancer coating. The quest for new carbon allotropes and future application persists.

Despite the advances in carbon-based technology, researchers have been limited to sp3 and sp2 hybridizations. While sp3 and sp2 hybridizations of carbon are well established and understood, the simplest sp1 hybridized carbon allotrope, carbyne, has been impossible to synthesize and remains elusive. This dissertation presents recent results in characterizing a new sp1 carbon material produced from using pulsed laser ablation in liquid (PLAL) to ablate a gold surface that is immersed in a carbon rich liquid. The PLAL technique provides access to extremely non-thermal environmental conditions where unexplored chemical reactions occur and can be explored to access the production of new materials. A combination of experimental and theoretical results suggests gold clusters can act as stabilizing agents as they react and adsorb onto the surface of one dimensional carbon chains to form a new class of materials termed “pseudocarbynes”. Data from several characterization techniques, including Raman spectroscopy, UV/VIS spectroscopy, and transmission electron microscopy (TEM), provide evidence for the existence of pseudocarbyne. This completely new material may possess outstanding properties, a trend seen among carbon allotropes, that can further scientific advancements.

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Date Created
  • 2018

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Synthesis and Characterization of Amphiphilic molecules for their use in health care industry

Description

Amphipathic molecules consist of hydrophilic and hydrophobic regions, which make them surface-active molecules. The uniqueness of these compounds results in inducing low surface tension and self-assembly of the molecules inside

Amphipathic molecules consist of hydrophilic and hydrophobic regions, which make them surface-active molecules. The uniqueness of these compounds results in inducing low surface tension and self-assembly of the molecules inside a solvent which have been exploited in personal care, the oil industry and agriculture industry. Amphipathic molecules are also used in the healthcare industry as drug delivery systems and other bio-nanotechnology applications.

In this thesis, a novel series of grafted siloxanes have been explored for their probable application in the healthcare industry. The siloxanes are grafted with poly(ethylene glycol) (PEG) and quaternary ammonium salt (QUAT). The effects of varying 1) molar ratios of QUAT to PEG and 2) PEG chain length on contact angle, surface tension, critical micelle concentration (CMC), and micelle assembly properties were studied. In contact angle experiments, the hydrophilicity of grafted siloxanes increased by grafting PEG and QUAT. The amphiphilicity increases and CMC decreases as the PEG chain length shortens. Adding QUAT also reduces CMC. These trends were observed in surface tension and Isothermal Titration Calorimetry experiments. A change in self-assembly behaviour was also observed in Dynamic Light Scattering experiments upon increasing the PEG chain length and its ratio relative to the quaternary ammonium in the siloxane polymer.

These polymers have also been studied for their probable application as a sensitive 1H NMR spectroscopy indicator of tissue oxygenation (pO2) based on spectroscopic spin-lattice relaxometry. The proton imaging of siloxanes to map tissue oxygenation levels (PISTOL) technique is used to map T1 of siloxane polymer, which is correlated to dynamic changes in tissue pO2 at various locations by a linear relationship between pO2 and 1/T1. The T1-weighted echo spin signals were observed in an initial study of siloxanes using the PISTOL technique.

The change in the ratio of QUAT to PEG and the varying chain length of PEG have a significant effect on the physical property characteristics of siloxane graft copolymers. The conclusions and observations of the present work serve as a benchmark study for further development of adaptive polymers and for the creation of integrated “nanoscale” probes for PISTOL oximetry and drug delivery.

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Date Created
  • 2018