Polymer Science Commons^™

Sustainable Two-Step Minlp Heat Exchanger Network Synthesis With Practical Detailed Design, Thanawat Boonvaerojkul

Chulalongkorn University Theses and Dissertations (Chula ETD)

Due to sustainable development that focuses on energy conservation, decreasing emissions and environmental effect, the research of heat exchanger network synthesis (HENS) is still necessary and challenging. Most academic studies in the subject of HENS aim on reducing total annual cost (TAC) through optimal topology design without the detailed design costs of each heat exchanger in the network, resulting in conceptual HEN designs. Hence, the detailed design of shell and tube heat exchangers is recalculated for TAC and corrected area costs, including the pumping costs from overall pressure drop of heat exchangers. For a shell and tube heat exchanger, its …

Nature-Inspired Material Strategies Towards Functional Devices, Sayantan Pradhan

Theses and Dissertations

Naturally sourced, renewable biomaterials possess outstanding advantages for a multitude of biomedical applications owing to their biodegradability, biocompatibility, and excellent mechanical properties. Of interest in this dissertation are silk (protein) and chitin (polysaccharide) biopolymers for the fabrication of functional biodevices. One of the major challenges restricting these materials beyond their traditional usage as passive substrate materials is the ability to combine them with high-resolution fabrication techniques. Initial research work is directed towards the fabrication of micropatterned, flexible 2D substrates of silk fibroin and chitin using bench-top photolithographic techniques. Research is focused on imparting electrochemical properties to silk proteins using conducting …

Complementary Techniques To Study The Behavior Of Water And The Effect On Diffusion And Degradation In Hydrogels, Paige Rockwell

Master’s Theses

Hydrogels exhibit biocompatibility in a range of biomedical applications, including drug delivery. This thesis aims to develop complementary techniques to measure the diffusion and degradation behaviors within an injectable, hydrolytically degradable hydrogel, formed via the covalent crosslinking of ethoxylated trimethylolpropane tri-3- mercaptopropionate (ETTMP) and poly(ethylene glycol) diacrylate (PEGDA), to determine its suitability as a drug delivery matrix. The characterization of water as either free, within the network openings of the hydrogel, or bound, tightly associated with the polymer chains, was determined using differential scanning calorimetry (DSC). The mobility of each type of water within the hydrogels was determined via nuclear …

Applied Machine Learning In Extrusion-Based Bioprinting, Shuyu Tian

Theses and Dissertations

Optimization of extrusion-based bioprinting (EBB) parameters have been systematically conducted through experimentation. However, the process is time and resource-intensive and not easily translatable across different laboratories. A machine learning (ML) approach to EBB parameter optimization can accelerate this process for laboratories across the field through training using data collected from published literature. In this work, regression-based and classification-based ML models were investigated for their abilities to predict printing outcomes of cell viability and filament diameter for cell-containing alginate and gelatin composite hydrogels. Regression-based models were investigated for their ability to predict suitable extrusion pressure given desired cell viability when keeping …

Extraction Of Micro- And Nano-Plastic Particles From Water Using Hydrophobic Natural Deep Eutectic Solvents, Jameson R. Hunter

Theses and Dissertations--Biosystems and Agricultural Engineering

The production of plastic and the amount of waste plastic that enters the environment increases every year. Synthetic polymers will gradually break down into particles on the micro- and nano-scale. The micro- and nano-plastics pose a significant ecological harm by transporting toxic chemicals and causing inflammation and cellular damage when ingested. Two common plastics are polyethylene terephthalate (PET) and Polystyrene (PS), and a newer bioplastic polylactic acid (PLA) that has become a popular alternative. Deep eutectic solvents are a recently discovered solvent composed of a hydrogen bond donor and hydrogen bond acceptor and have been proposed as a cheaper alternative …

Development Of An Injectable Methylcellulose Hydrogel System For Nucleus Pulposus Repair And Regeneration, Nada A. Haq-Siddiqi

Dissertations and Theses

Low back pain is the most common cause of disability in the world and is often caused by degeneration or injury of the intervertebral disc (IVD). The IVD is a complex, fibrocartilaginous tissue that allows for the wide range of spinal mobility. Disc degeneration is a progressive condition believed to begin in the central, gelatinous nucleus pulposus (NP) region of the tissue, for which there are few preventative therapies. Current therapeutic strategies include pain management and exercise, or surgical intervention such as spinal fusion, none of which address the underlying cause of degeneration. With an increasingly aging population, the socioeconomic …

Assessing Solvent Viscosity Impact On The Physical Characteristics Of Polymeric Organogels, Cameron Hong

Honors Theses

Traditionally, studies of polymeric organogels focus on the impact of polymer factors (e.g., molecular weight and polymer concentration) on the gels’ mechanical and transport properties. Alternatively, this study seeks to assess the impact of altering solvent viscosity, while holding polymer factors constant. The gels in this study were composed of different viscosity mineral oils, styrene-ethylene-butylene-styrene (SEBS) triblock copolymer as a gelator, and oleic acid (OA) as a model drug. Samples were formulated to have 6.5, 11.2, and 15.7 wt% SEBS copolymer for each mineral oil, varying in viscosity from ≈30 mPa*s to ≈500 mPa*s. Uniaxial mechanical testing was performed to …

Assessing The Impact Of Block-Selective Homopolymers On The Diffusion Of Payload Through Polymeric Organogels, Ian Coates

Honors Theses

Styrenic polymer gels have received recent attention for their application in transdermal patches due to their unique properties. Previous research in the pharmaceutical industry has identified that polymeric gels, specifically styrenic gels, have the potential to encompass multiple functions of the transdermal delivery patch including controlling mechanical and delivery properties. To tailor styrenic gels either the gel nanostructure or the drug complex can be controlled. Specifically, this thesis investigated the effect of gel nanostructure in an attempt to control the gel diffusivity and mechanical properties. To control gel nanostructure a phase selective styrene homopolymer was used at varying concentrations. It …

Determination Of Hydrogel Degradation By Passive Mechanical Testing, Avery Rosh-Gorsky

Honors Theses

This paper details a new technique to measure the mechanical properties of ETTMP PEGDA hydrogels using Hertz Contact Theory and simultaneously analyze both the model drug release and gel erosion in situ. This method involves curing a drug loaded hydrogel in a standard cuvette and placing a glass bead and phosphate buffer solution (PBS). Over time, the cross-linked network of the hydrogel breaks down, and, as a result, the ball sinks into the hydrogel. This method provides a macroscopic and inexpensive way to continuously and passively measure properties of the hydrogel as the hydrogel degrades. By plotting both the …

Helicopter Shaft Heating Parameters For Polyamide-11 Coating, Selim Kevran Ph.D, Uğur Ati̇ci̇

International Journal of Aviation, Aeronautics, and Aerospace

In this study, the heating parameters required for polyamide-11 (P11) coating of the helicopter shaft were investigated. The torsion value created by the force applied to the middle of the helicopter's shaft is measured. Heating before coating affects the torsion value of the shaft. A new heating mechanism has been designed to cover the shaft surface without changing the torsion value of the shaft. Thus, the coating surface is left inside the furnace and the torsion measurement area outside of the furnace. Taguchi method was used to determine heating parameters such as furnace type, initial temperature and heating time. The …

Establishing Independent Tunability Of The Mechanical And Transport Properties Of Polymer Gels, Lucas Rankin

Master’s Theses

Polymer gels can be used in the fabrication of materials for filtering liquid and gaseous media, solid-state electrolytes, and transdermal medical patches. This diverse range of applications primarily relies on the transport and mechanical properties of polymer gels. Both sets of properties have shown excellent tunability, but typically in a coupled fashion. Establishing the independent tunability of the transport and mechanical properties of polymer gels (using simple, cost-effective methods) is paramount if polymer gels are to be used to their full potential. Specifically, block copolymer gels self-assemble into organized nanoscale networks within the gel solvent, which allows for facile control …

Evaluating The Thermoresponsive Properties Of Hydroxypropyl Cellulose Solutions For Smart Window Applications, Adam Reed

Williams Honors College, Honors Research Projects

With HVAC and building energy usage expected to increase, there is a strong need for autonomous thermal management solutions. In particular, there has been a growing interest in thermoresponsive (TR) smart windows that are activated by ambient temperature changes. Most TR smart windows contain a liquid solution between two panes. The goal of this research project was to develop a self-supporting smart window by forming a gel that maintained its TR properties. A gel is less prone to spilling in the case of window breakage. It was also desired to tune the phase transition to occur at environmentally relevant conditions …

Wetting Transition On 3d-Printed Featured Surface, Hannah Pineault

Williams Honors College, Honors Research Projects

The primary objective of this research project was to gain a better understanding of surface characteristics to produce a long-lasting superhydrophobic or superhydrophilic surface. In other words, when will a droplet of water remain on top of a featured surface and when does the transition occur to water filling the grooves of the surface? This research focused on how to best fabricate porous structures that would stay completely dry at all times by preventing the liquid from penetrating. In particular, we followed the behaviors of water droplets placed on top of 3-D printed featured surfaces with various geometries and surface …

Comparison Of The Effects Of Hofmeister Ions On Transition Temperature Of Two Thermoresponsive Polymers, Ashley Knight

Williams Honors College, Honors Research Projects

It has been hypothesized that poly(vinylmethylether) (PVME) could be used to replace poly(N-isopropylacrylamide) (pNIPAAM) in various thermoresponsive applications based on literature searches and previous lab experiments. PVME is cheaper and easier to process, and would make pNIPAAM applications more cost effective. In order to verify this, experimental data was gathered on the effects of four anions from the Hofmeister series (SO₄₂-, Cl-, I-, and SCN-) on the lower critical solution temperature (LCST) of pNIPAAM and compared to previous data collected on PVME. Commercial pNIPAAM from Sigma Aldrich and Polysciences were used. The reported LCST range for pNIPAAM is …

Investigation Of Surface Charge Using Faraday Bucket Measurements: Analysis On Electrospun Polyvinylidene Fluoride Fiber Mats, Ryan Kantenwein

Williams Honors College, Honors Research Projects

Piezoelectric polymer materials such as polyvinylidene fluoride exhibit beneficial properties for use in personal protective equipment (PPE) against viral contaminants and other foreign microparticles. The electrospinning process of this material allows for surface charge to develop over a controlled surface area. Kynar 761 at 10 wt% demonstrates increased surface charge after withstanding a flow of aerated NaCl particles from a TSI 8130 instrument. Utilizing voltage measurements from a Faraday bucket, 18 wt% Kynar 761 and MG-15 exhibit surface charge when undergoing an electrospinning process; however, Kynar MG-15 displays lower charge values than that of Kynar 761. Several critical factors such …

Quantifying Mafenide Release From 3d Printed Phenylalanine-Coumarin Copolyester Scaffolds, Jacob Seeh

Williams Honors College, Honors Research Projects

This project addressed burn wound healing through controlled release of the antibacterial drug mafenide encapsulated by a copolyster into 3D printed scaffolds. Scaffolds were printed at 25^oC and 0.77-1 bar in a cross-hatch pattern with uniform thickness, distance between parallel layers, and diameter then photo-crosslinked. The number of scaffolds available for testing was limited by the amount of polymer that could be synthesized. A high-performance liquid chromatography method was developed specifically for this experiment and used to determine daily release of mafenide from the scaffold into a 2-mL phosphate buffer solution. During the first 24 hours a large …

Molecular Recognition Of Pet Depolymerization Products And Beta-Cyclodextrin, Thomas Palisin

Williams Honors College, Honors Research Projects

Using molecular recognition techniques to determine the binding constant of the host-guest relationships of the depolymerization products of polyethylene terephthalate (PET) and cyclodextrin species. The main method of data collection used was florescence spectroscopy. Using a titration method and measuring the florescence intensity, a nonlinear regression was used to determine the binding constant.

The Critical Role Of Dynamic Surface Tension Of Surfactants On The Impact Dynamics Of Water Droplets, Amir Esmaeili, Reza Mohammadi

Graduate Research Posters

Due to their time-dependent surface tension, the addition of surface-active agents or surfactants to water for specific applications has made controlling the impact dynamics of these droplets a complex phenomenon. This work investigates the influence of the molecular weight, concentration, and ionic nature of the surfactants as well as the substrate surface characteristics on the impact dynamics of surfactant-laden droplets using a high-speed camera at 10000 frames per second. Sodium dodecyl sulfate, hexadecyltrimethylammonium bromide, and n-decanoyl-n-methylglucamine were used as anionic, cationic, and nonionic surfactants, respectively. We used hydrophilic glass slides, hydrophobic polytetrafluoroethylene, and superhydrophobic alkyl ketene dimer (AKD) as substrates. …

Valorization Of Xylan In Agroforestry Waste Streams, Harrison Appiah

Graduate Theses, Dissertations, and Problem Reports (ETD)

Valorization of Xylan in Agroforestry Waste Streams.

Harrison Appiah

Microwave-assisted deep eutectic solvent and gamma-valerolactone metallic chloride catalyzed conversion of xylan to furfural were investigated using a 2x3 factorial experimental design at two levels of percent microwave power, reaction time, and catalyst concentration. The levels of each factor studied were (20%, 60% microwave power, 2, 4 minutes, and 10, 20mg) respectively. The effect of three metallic chloride catalysts (LiCl, FeCl3.6H20, CuCl2) on the conversion of xylan to furfural was also investigated. The gamma-valerolactone-ferric chloride sent system exhibited the highest mean yield of furfural (56.50%). The next highest furfural yield of …

Tailoring Thermoresponsive Poly(N-Isopropylacrylamide) Toward Sensing Perfluoroalkyl Acids, Dustin Thomas Savage

Theses and Dissertations--Chemical and Materials Engineering

Widespread distribution of poly- and perfluoroalkyl substances (PFAS) in the environment combined with concerns for their potentially negative health effects has motivated regulators to establish strict standards for their surveillance. The United States Environmental Protection Agency issued a cumulative domestic threshold of 70 ppt for water supplies, and this bar is even lower in some local districts and other countries. Monitoring PFAS consequently requires sensitive analytical equipment to meet regulatory specifications, and liquid chromatography with tandem mass spectroscopy (LC/MS/MS) is the most common technique used to satisfy these requirements. Though extremely sensitive, the instrument is often burdened by pretreatment regimens, …