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Full-Text Articles in Engineering
Effects Of Polymer Side-Group Size On Interfacial Mechanics Of Graphene-Polymer Nanocomposites, Grace Brokaw
Effects Of Polymer Side-Group Size On Interfacial Mechanics Of Graphene-Polymer Nanocomposites, Grace Brokaw
All Theses
Graphene-reinforced polymer nanocomposites possess excellent mechanical, thermal, and electrical properties, which make them promising candidates for various applications. Favorable interfacial interactions and mechanics between graphene sheets and polymer matrices are often essential to achieve superior mechanical properties. Nevertheless, it remains largely elusive how molecular features of polymer systems, particularly the side-group size of polymer chains, affect the interfacial mechanics between graphene sheets and polymer matrices, primarily due to challenges in well controlling these features in experiments. On the other hand, exploring their roles in the mechanical properties of graphene-polymer nanocomposites is very expensive to study with all-atomistic molecular dynamics (MD) …
Characterization Of Thermal Gelation Properties In Bioresorbable Thermally Activated Hydrogel Polymers For Hernia Surgery Applications, Alexander Mayfield
Characterization Of Thermal Gelation Properties In Bioresorbable Thermally Activated Hydrogel Polymers For Hernia Surgery Applications, Alexander Mayfield
All Theses
Hydrogel adhesives are a new class of materials with excellent biocompatibility, which makes them very attractive for biomaterial applications. It has been previously shown that Tetronic T1107, a four-arm poly (propylene oxide)-poly (ethylene oxide) (PPO-PEO) block copolymer, is useful as a chemical crosslinking thermo-responsive hydrogel for bioadhesive applications. The end groups of this polymer are modified with acrylate and N-hydroxysuccinimide (NHS) functional groups. The acrylate end group gives the polymer cohesive properties with long-range chemical crosslinking using dithiothreitol (DTT), while the NHS end group gives the polymer adhesive properties through bonding with amines found in organic tissue. It was found …
3d Printed Multicomponent Polymer Based Materials Via Hybrid Filaments: Fabrication And Characterization, Erik Antonio
3d Printed Multicomponent Polymer Based Materials Via Hybrid Filaments: Fabrication And Characterization, Erik Antonio
All Dissertations
Additive manufacturing, also known as 3D printing, promises a manufacturing revolution for both industry and academic circles. One of the most widely used method of 3D printing is Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF), which requires a thermoplastic filament to be directed towards a heating block and then deposited via extrusion layer by layer to produce a finished part. However, there are significant issues with this technology, mainly a limitation on the materials available for use and mechanical property deficiencies when compared to traditional manufacturing. These issues are brought about by the temperature limited nature of the …
Analysis Of The Self-Heating Effect On Unfilled Poly(Methyl Methacrylate) Due To Cyclic Behavior, Muhammed R. Kose
Analysis Of The Self-Heating Effect On Unfilled Poly(Methyl Methacrylate) Due To Cyclic Behavior, Muhammed R. Kose
All Theses
Poly(methyl methacrylate, (PMMA) has been implemented as part of the supporting structure in complete hip and knee replacements since the 1950s. Known as bone cement while in the body, PMMA is known to undergo compressive and tensile stresses that wear down the bio-compatible barrier and cause pieces to come loose inside the human body. These pieces are then attacked by the body’s own nervous system, leading to inflammation, and eventually necessitating replacement. It has been documented that under cyclic loading PMMA can reach temperatures that start to degrade its tensile capabilities. In this study the potential cause of self-heating was …
Graphene Oxide-Thermoplastic Nanocomposites: Fabrication And Properties, Seyedeh Mastooreh Seyedi Ghezghapan
Graphene Oxide-Thermoplastic Nanocomposites: Fabrication And Properties, Seyedeh Mastooreh Seyedi Ghezghapan
All Dissertations
Polymer nanocomposites are used for a wide variety of applications. These nanocomposites can have a number of important characteristics depending on the nature of the nanomaterial, its size, volume fraction, its distribution, and interactions within the host polymer. Mechanical strength, thermal and electrical conductivity are some of these materials' most focused and studied features. Besides the positive influences of the reinforcements, nanomaterials also might have some adverse impacts on the polymer matrix. These issues could arise from the aggregation of the fillers and the poor interfacial interactions of the components. Several approaches are introduced to modify the nanofillers and enhance …
Synthesis And Characterization Of Glycidyl Methacrylate-Based Graft Copolymer Functional Interfaces, Nikolay Brordinov
Synthesis And Characterization Of Glycidyl Methacrylate-Based Graft Copolymer Functional Interfaces, Nikolay Brordinov
All Dissertations
Modification of materials properties such as surface energy, wettability, ability to absorb, contain or release specific type of chemicals enables practical application of these materials in various scientific and engineering set-ups. However, designing protocol that could be easily adapted for different situations and simultaneously unlock multiple variations of the resulting properties is a non-trivial task. This dissertation is devoted to application of glycidyl methacrylate-based graft copolymers for the purposes of surface modification, establishing fundamental trends and dependencies of this process and exploring the possible range of applications. These materials have extremely valuable property to undergo controllable post-synthetic modifications including surface …
Synthesis And Characterization Of Chemically Functionalized Shape Memory Nanofoams For Unattended Sensing Applications, Anna Paola Soliani
Synthesis And Characterization Of Chemically Functionalized Shape Memory Nanofoams For Unattended Sensing Applications, Anna Paola Soliani
All Dissertations
The work in this dissertation is devoted to the synthesis and characterization of novel materials for off-line unattended sensing: shape-memory grafted nanofoams. The fabrication process and characterization of highly efficient, polymeric nanosensor element with the ability to selectively detect analytes and retain memory of specific exposure events is reported. These shape memory nanofoams could potentially act as efficient and highly sensitive coatings for evanescent waveguide-based optical monitoring systems. On exposure to specific analytes, the polymeric coatings locally change their internal structure irreversibly at the nanolevel, affecting the local optical properties such as refractive index. Currently, enrichment polymer layers (EPLs) are …
Engineering Single-Molecule, Nanoscale, And Microscale Bio-Functional Materials Via Click Chemistry, Michael Daniele
Engineering Single-Molecule, Nanoscale, And Microscale Bio-Functional Materials Via Click Chemistry, Michael Daniele
All Dissertations
To expand the design envelope and supplement the materials library available to biomaterials scientists, the copper(I)-catalyzed azide-alkyne cycloaddition (CuCAAC) was explored as a route to design, synthesize and characterize bio-functional small-molecules, nanoparticles, and microfibers. In each engineered system, the use of click chemistry provided facile, bio-orthogonal control for materials synthesis; moreover, the results provided a methodology and more complete, fundamental understanding of the use of click chemistry as a tool for the synergy of biotechnology, polymer and materials science. Fluorophores with well-defined photophysical characteristics (ranging from UV to NIR fluorescence) were used as building blocks for small-molecule, fluorescent biosensors. Fluorophores …
Probing And Controlling Fluid Rheology At Microscale With Magnetic Nanorods, Alexander Tokarev
Probing And Controlling Fluid Rheology At Microscale With Magnetic Nanorods, Alexander Tokarev
All Dissertations
This Dissertation is focused on the development of new methods for characterization and control of fluid rheology using magnetic nanorods. This Dissertation consists of five chapters. In the first chapter, we review current microrheologial methods and develop a Magnetic Rotational Spectroscopy (MRS) model describing nanorod response to a rotating magnetic field. Using numerical modeling, we analyze the effects of materials parameters of nanorods and fluids on the MRS characteristic features. The model is designed for a specific experimental protocol. We introduce and examine physical parameters which can be measured experimentally. The model allows identification of MRS features enabling the calculation …
Quantitative Analysis And Structural Characterization Of Carbonaceous Pitches, Sourabh Kulkarni
Quantitative Analysis And Structural Characterization Of Carbonaceous Pitches, Sourabh Kulkarni
All Dissertations
Both petroleum pitches and pitches derived from pure polycyclic aromatic hydrocarbons (PAHs) are oligomeric materials that can serve as precursors for a wide variety of advanced carbon materials. The goal of this study was the structural characterization and quantitative analysis of the dominant constituent oligomers and species present in these pitches.
A key requirement for such work is the ability to fractionate these complex mixtures into samples of narrow molecular weight distribution (mol wt; MWD) that can be used as standards. To this end, semicontinuous (or semibatch) dense-gas/supercritical extraction (DGE/SCE) was used to produce monomer, dimer, and trimer fractions of …
Synthesis And Characterization Of Macromolecular Layers Grafted To Polymer Surfaces, Oleksandr Burtovyy
Synthesis And Characterization Of Macromolecular Layers Grafted To Polymer Surfaces, Oleksandr Burtovyy
All Dissertations
The composition and behavior of surfaces and interfaces play a pivotal role in dictating the overall efficiency of the majority of polymeric materials and devices. Surface properties of the materials can be altered using surface modification techniques. It is necessary to highlight that successful methods of surface modification should affect only the upper layer of the polymer material without changing bulk properties. The processes must introduce new functionalities to the surface, optimize surface roughness, lubrication, hydrophobicity, hydrophilicity, adhesion, conductivity, and/or biocompatibility.
Research presented in this dissertation is dedicated to the synthesis, characterization, and application of thin macromolecular layers anchored to …
Kinetics Of Preferential Adsorption And Equilibrium Properties Of Interfacial Layers Formed From Polymer Chains That Tether By Multiple Ends, Jose Alonzo Calderon
Kinetics Of Preferential Adsorption And Equilibrium Properties Of Interfacial Layers Formed From Polymer Chains That Tether By Multiple Ends, Jose Alonzo Calderon
All Dissertations
Due to their ability to straddle phase boundaries, polymer brushes represent a model system for studies of polymer-modified surfaces. The research presented in this dissertation focuses on understanding a special type of polymer brushes formed at the solid-fluid interface by self-assembly of block copolymer chains that have the ability to tether by multiple ends, thus creating loops on the surface. Specifically, I study the self-assembly of a series of poly(2-vinylpyridine)-polystyrene-poly(2-vinylpyridine) (PVP-b-PS-b-PVP) triblock copolymers and PVP-b-PS star block copolymers adsorbed from the selective solvent toluene onto silicon and mica surfaces. The triblock and star copolymers have different molecular weights and PS/PVP …
Real-Time Raman Spectroscopy And Wide-Angle X-Ray Diffraction During Single-Layer And Multi-Layer Blown Film Extrusion, Giriprasath Gururajan
Real-Time Raman Spectroscopy And Wide-Angle X-Ray Diffraction During Single-Layer And Multi-Layer Blown Film Extrusion, Giriprasath Gururajan
All Dissertations
Properties exhibited by blown films are controlled by the microstructure developed during their processing. Therefore, real-time measurement of microstructure during the blown film extrusion can help in better control and optimization of the process needed to obtain desired properties. The objectives of this research were (i) to conduct real-time microstructural measurements during single-layer and multi-layer blown film extrusion of polypropylene (PP) and low-density polyethylene (LDPE) using real-time Raman spectroscopy; (ii) to conduct real-time wide-angle X-ray diffraction (WAXD) during single-layer blown film extrusion of LDPE to obtain crystallinity and orientation values during the process; and (iii) to investigate the effect of …
Effect Of Carbon Nanofibers On Microstructure And Properties Of Polymer Nanocomposites, Sungho Lee
Effect Of Carbon Nanofibers On Microstructure And Properties Of Polymer Nanocomposites, Sungho Lee
All Dissertations
Nano-modifiers are typically three orders of magnitude smaller in size than their micro-counterparts. At this scale, interactions between matrix molecules and the nano-modifiers can lead to novel physical and chemical properties of the resulting nanocomposites. Carbon nanofibers (CNFs) are a class of nano-modifiers that has received significant attention recently because they have superior electrical conductivity and mechanical properties with a high aspect ratio (length over diameter). Several recent research studies have focused on enhancing electrical and mechanical performance of composites in the presence of CNFs. However, the influence of CNFs on the structure of the polymer matrix is important in …