Polymer Science Commons^™

The Cosolvent And Association Effect On Polymer Behaviors, Xiangyu Zhang

Theses and Dissertations

The blending or mixing is extensively utilized in diverse processes of polymers to bring about advantageous properties, but the behavior becomes intriguing when associations are involved and multi-solvents are used. Explanations based on chemistry-specific arguments are less than satisfactory in abstracting essential features, and lack the general applicability across various systems. So, this work focuses on capturing the physical force governing the phenomenon of interest by using a generic model. Highly non-trivial behaviors of polymers are often observed in multi-solvent solutions. It is known that polymers swell and dissolve in good solvents, while they tend to collapse and aggregate in …

Carbon Fibers From Athabasca Oil-Sand Asphaltenes, Blake Reardon

All Theses

Carbon fibers possess ultra-high specific strength and modulus. Therefore, the material is popular in aerospace, automotive, and sports industries. Approximately 95% of all carbon fibers are spun from a high-cost precursor, polyacrylonitrile (PAN). There is a need for a cheaper grade of carbon fiber for low-cost applications because about half of carbon fiber cost is associated with precursor cost. A promising alternative to the high-cost PAN precursor is petroleum-based asphaltene. Asphaltenes are highly aromatic and have a high carbon content but lack the purity of the PAN precursor. Processes like the molten- sodium desulfurization upgrading have been used to harvest …

Characterization Of Mechanically Recycled Polylactic Acid (Pla) Filament For 3d-Printing By Evaluating Mechanical, Thermal, And Chemical Properties And Process Performance, Mahsa Shabani Samghabady

All Theses

Polylactic acid (PLA) is a biopolymer made from renewable resources such as sugar and corn. PLA filament is a popular material used in Fused Deposition Modeling (FDM) 3D-printing. While this material has many advantages, all the failed parts, support structures, rafts, nozzle tests, and the many prototype iterations during the 3D-printing process contribute to the plastic pollution and release of greenhouse gases. Although PLA is biodegradable, it can take years to degrade in landfills. Instead of throwing away PLA waste and buying new filaments, PLA can be recycled. Amongst the different recycling technologies, mechanical recycling is the most environmentally friendly. …

Activated Carbon Synthesis From Lignin-Rich Byproduct Streams Of Biorefineries, Chengjun Wu

All Dissertations

Over the past decade, the production of biofuels from lignocellulosic biomass has steadily increased to offset the use of fuels from petroleum. To make biofuels cost-competitive, it is necessary to add value to the “ligno-” components (up to 30% by mass) of the biomass. Instead of just burning it for heat and electricity generation, direct conversion of lignin carbon into a product provides a complementary path to carbon capture, promoting a more environmentally conscious approach. However, the utilization of these lignin-rich byproduct streams, which are separated from the biofuels production, for industrial products can be challenging. The use of specific …

Improving Lignin Recovery From Paper Mill And Biorefinery Waste Streams Via Liquid-Phase Splitting, Carter Fitzgerald

All Dissertations

Lignin is an abundant biopolymer with significant promise due to its aromaticity. It has been targeted as a replacement for a number of petroleum-based products including adhesives, coatings, polyurethane foams, activated carbon, and carbon fibers. However, commercially available bulk lignins are too polydisperse, and contain too many residual metals from the pulping process that are detrimental to the properties of the final product.

The Sequential Liquid-lignin Recovery and Purification (SLRP) process was developed by Michael Lake and John Blackburn, in collaboration with Clemson, with the intention of creating a continuous method for recovering lignin from paper-mill black liquors. Thies and …

Development Of Non-Viral Nano-Carriers For Gene Delivery And Covid-19 Vaccines, Zhongyu Li

Dissertations

Gene therapy is one of the most promising medical fields with the potential to effectively advance the treatment of difficult diseases by producing therapeutic proteins or repairing defective gene sequences. However, gene therapy presents severe challenges in delivery including renal clearance, phagocytosis, enzymatic degradation, protein absorption, and cellular internalization barriers, which have been barriers for translation into the clinic. Naked nucleic acids, with their intrinsic negative charge, electrostatically repulse the anionic cell membrane, preventing cellular uptake. Also, they are considered foreign genetic material when introduced into the body and are rapidly cleared by the reticuloendothelial system or degraded by nucleases, …

The Biological Activity Of Dual-Responsive Glycopolymers For Intracellular Codelivery Of Antigen And Lipophilic Adjuvant, Micaela Shields

Honors Theses

Subunit vaccines present themselves as an attractive alternative to traditional approaches to vaccines, which utilizes whole organisms to trigger an immune response. While these traditional approaches have proven themselves reliable within the history of vaccinations, they generally deliver subpar robust cellular-mediated immunity and pose many safety risks. Composed of proteins and /or peptides, subunit vaccines are safer and more precise alternatives to traditional approaches. However, the pharmacokinetic properties of the macromolecules that make up these vaccines hinder the subunit vaccine’s level of immunogenicity [d1] Examples of this hindrance include but are not limited to aggregation at the injection site and …

Enhancing Compatibility And Mechanical Properties Of Natural Rubber Composites, Krisma Yessi Sianturi, Adam Febriyanto Nugraha, Belle Kristaura, Mochamad Chalid

Journal of Materials Exploration and Findings

Pure natural rubber (NR) exhibits low mechanical properties, necessitating the incorporation of additives like vulcanizing agents and fillers. Carbon black and silica, conventional fillers, are relatively expensive and not environmentally friendly. This study explores using Oil Palm Empty Fruit Bunch (OPEFB) fiber as an affordable, abundant, and biodegradable alternative filler for NR. However, compatibility issues arise between the nonpolar NR and the polar OPEFB fiber. A latex-starch hybrid coupling agent (CA (NR-St)) was added to the composite formulation to address this. NR, OPEFB fiber, and the coupling agent were mixed using an open roll mill with a 10 phr OPEFB …

Chloramine Devulcanization Of Waste Rubber., Patrick Kroeger

Electronic Theses and Dissertations

The disposal of waste rubber, particularly tire rubber, continues to pose a challenge in the 21st century. As a result, most end-of-life tires (ELTs) are either dumped in landfills or burned as tire-derived fuel. Chloramine devulcanization may offer a viable solution to this problem. Chloramine devulcanization is a low-temperature, low-pressure, process that selectively breaks sulfur crosslinks while preserving the polymer backbone. Chloramine devulcanization enables the recovery of chloramine recovered carbon black (CrCB) and devulcanized rubber (CdR) as separate products. Initial analysis of CdR revealed that it was formable and malleable, suggesting that crosslinking was absent. Spectroscopy showed that CdR contained …

Interactions And Phenomena Between Disodium Cromoglycate And Polyelectrolytes, Brandon Tipton

Chemical Engineering Undergraduate Honors Theses

The interactions between polyelectrolytes and oppositely charged macroions have been widely studied, but few reports have been made on the interaction between chromonic mesogens and polyelectrolytes. Here, we report on the formation of liquid crystalline coacervates achieved by the liquid-liquid phase separation of an aqueous solution of negatively charged liquid crystal and polycations. As well as the occurrence of tactoids that form in the absence of these interactions. The liquid crystal that is experimented with is disodium cromoglycate, better known as DSCG. This acts as a negative charge that is paired with a variety of positively charged polyelectrolytes. The first …

Lignin Copolymer Property Prediction Using Machine Learning, Collin Larsen

Chemical Engineering Undergraduate Honors Theses

Lignin, an abundant biopolymer, is a waste byproduct of the paper and pulp industry. Despite its renewable nature and potential applicability in various products, such as plastics and composites, the development of lignin-based materials has been impeded by the cumbersome, Edisonian process of trial and error. This research proposes a novel approach to forecasting the properties of lignin-based copolymers by utilizing a recurrent neural network (RNN) based on the Keras models previously created by Tao et al. Example units of modified lignin were synthesized via esterification and amination functional group modifications. To increase the efficiency and accuracy of the prediction …

Elucidating The Mechanical And Transport Properties Of Lignin-Based Hydrogel Composites, Nicholas Gregorich

All Dissertations

The use of lignin in the fabrication of soft composites has become an emerging area of research in polymer science and polymer chemistry. These lignin-based materials present numerous benefits, notably, a reduction in the use of petroleum-based precursor, improved structural benefits to otherwise soft host polymers, as well as the inherent antimicrobial and antioxidant properties of lignin, making it suitable for biomaterials. Herein, we present two chemical reaction pathways of incorporating lignin that was fractionated and cleaned using the Aqueous Lignin Purification with Hot Agents (ALPHA) process into poly(vinyl alcohol) (PVA) hydrogel composites for aqueous-based separations. By leveraging the ALPHA …

Bridging The Gap Between Phase Behavior And Processing For Renewable And Refinable Carbonaceous Precursors, Graham Tindall

All Dissertations

As a category of materials, engineered carbons, specifically carbon fibers, are first-in-class for properties such as modulus, specific strength, and thermal resilience; however, the inability to directly process atomic carbon necessitates the development and optimization of carbonaceous precursors. Because the structure and properties of carbon are highly dependent on the precursors and requisite processing, numerous materials have been investigated as feedstocks for large-scale production. Although cellulose and rayon were among the first investigated, polyacrylonitrile (PAN) is the current hegemon of carbon fiber precursors. PAN feeds 90% of this market, but it is neither inexpensive nor renewable. Because a significant fraction …

Characterization Of Lignin And Cellulose Biopolymers Structure – Function Relationships, Zachariah Pittman

All Dissertations

Biomass is vital to ongoing efforts to secure a sustainable future. While many of our efforts focus on finding alternative forms of energy, biomass among them, only biomass has the potential to serve as a sustainable materials feedstock. However, biomass is heterogenous, complicating the upgrading processes needed to manufacture commodity and performance products. For example, plant biomass consists largely of cellulose, a crystalline polysaccharide, and lignin, a highly stable polyaromatic. The specific properties of cellulose and lignin depend greatly on the plant, harvesting conditions, and isolation procedures. Thus, accurate and reliable determination of the fundamental properties of biomass is crucial …

Removal Of Hexavalent Chromium From Water By Chitosan-Enhanced Ultrafiltration, Putu A. Y. Indiasih, Anindita D. Syaifudin, Nurul Faiqotul Himma, Bambang Ismuyanto

Makara Journal of Technology

Polymer-enhanced ultrafiltration has gained increasing attention as a selective separation process to remove small solutes, such as metal ions, from water or wastewater. Hexavalent chromium Cr(VI) is one of the metal ions in wastewater that has received considerable attention because of its toxicity. Chitosan was used in this study as the polymer to bind Cr(VI) to enhance its removal by ultrafiltration. The effects of chitosan-to-Cr(VI) ratio on Cr(VI) rejection and permeate flux were investigated. In addition, the fouling tendency was evaluated. Results showed that the addition of chitosan with a mass ratio of 12.5 increased the Cr (VI) rejection from …

Poly(Ether Imide)S: Synthesis And Properties, Rachel Price

Honors College Theses

The synthesis of strong polymers is crucial to the creation of heat-resistant, durable, and mechanically useful plastics that we use every day. Poly(ether imide)s are used in applications such as food service, aerospace, automotive, and many more. This thesis will discuss the synthesis and properties of these plastics to help express a larger understanding of these polymers.

Hydrothermal Liquefaction Of Saccharina Latissima For The Production Of Biofuel, Mayokun A. Oke

Mechanical Engineering Theses

We performed hydrothermal liquefaction of brown macroalga (Saccharina latissima) in the presence of homogenous and heterogenous catalysts such as KOH, Na₂CO₃, Pd/C, HZSM-5, Ce/HZSM-5, and Ni/SiO₂-Al₂O₃ in hot compressed water, to investigate their effects on product yield and composition in the biocrude. To investigate hydrocarbon production, we used methanol as co-solvent (methanol-to-water 1/4 vol.%) and as the only liquefaction solvent. We carried out the experiments in a batch reactor at 330^oC and 120-130 bar, and varying temperature, algae-to-water ratio, residence time, and pretreatment method. The biocrude yields …

Comparing Weathering Effects Of Ultraviolet And Xenon Arc Accelerated Aging On Polyvinyl Chloride, Collin Mcinnes

Williams Honors College, Honors Research Projects

As the ubiquitousness of polymers increases and begins seeing use in outdoor settings, the need to fully understand how these materials degrade is also necessary. This study aims to compare two known accelerated aging methods, namely an ultraviolet light chamber and a xenon arc light chamber, to understand what differences, if any, manifest in the mechanical, chemical, and cosmetic deterioration of polyvinyl chloride (PVC) after long-term exposure. The study utilizes Fourier-transform infrared spectroscopy, dynamic mechanical analysis, thermogravimetric analysis, and colorimetry analysis to determine the extent of degradation and potential discrepancies between the aging methods.

Chemical Decomposition Of Flexible Polyurethane Foam To Generate A Media For Microbial Upcycling, Kaushik Baruah

Dissertations, Master's Theses and Master's Reports

Polyurethane waste is becoming a global concern as a large amount is being disposed of in landfills every year, and only a fraction is being recycled. Several polyurethane recycling techniques exist, of which ammonolysis and base-catalyzed hydrolysis is the least explored. Flexible polyurethane foam (FPUF) decomposition can generate amines that can act as a carbon source for the growth of microbial consortia. This study aims to generate a novel media capable of microbial upcycling via ammonolysis and base-catalyzed hydrolysis of flexible polyurethane foams (FPUFs) using ammonium hydroxide and subsequently determine the reaction conditions for maximum solubilization of polyurethane foam in …

Running Shoe Pedometer, Benjamin Kasper

Williams Honors College, Honors Research Projects

Running shoe pedometer aims to solve the issue of worn out running shoes. It can be difficult to know just how many miles you have run in your shoes and when a new pair is needed. Running in old shoes and worn out shoes is heavily linked to injury. My proposed project is a device that is powered by the compressive forces on the shoes soles that counts the number of steps the wearer takes using a microcontroller. Then, when the shoe reaches milestone that indicate it has been used 75% 90% and 100% of its expected life, it will …