Polymer and Organic Materials Commons^™

Modular Composite Sandwich Structures For Thermal And Structural Retrofitting Of Existing Buildings, Marc Al Ghazal

Masters Theses

Around 40% of global energy consumption and 30% of worldwide carbon dioxide (CO2) emissions are attributed to buildings. Most of this consumption is dedicated to ensuring thermal comfort. The goal of this research was to develop and field validate retrofit solutions to improve the energy efficiency of buildings. Exterior cladding panels were designed and tested to ensure adequate thermal and structural performance. Sandwich panels (glass fibers reinforced polymer (GFRP) skins and polymeric foam cores) were fabricated using the vacuum assisted resin transfer molding (VARTM) process. Extruded polystyrene (XPS) and polyurethane (PU) foams were compared as core materials through a series …

Comparative Analysis On Low Cost Continuous Carbon Fiber Polypropylene Composite Using Compression Molding And Automated Tape Placement, Benjamin U. Schwartz

Masters Theses

Carbon fiber reinforced plastics (CFRP) are widely used throughout the aerospace industry where a weight reduction remains the highest priority with less emphasis on cost. Textile grade carbon fiber (TCF) and other low cost carbon fiber (LCCF) alternatives have recently emerged for use in the automotive market where emissions regulations have pushed automotive manufacturers and research institutions to look for cost effective light weight materials. Fiber reinforced thermoplastics provide an effective solution that align with automotive design including low cost, high processing rates, high impact toughness, unlimited shelf life, and recyclability.

TCF and Zoltek_PX35 fibers are two LCCF aimed at …

Optimized 3d-Printing Of Carbon Fiber-Reinforced Polyether-Ether-Ketone (Cfr-Peek) For Use In Overmolded Lattice Composite, Ryan C. Ogle

Masters Theses

Current orthopedic implants are overwhelmingly composed from metallic materials. These implants show superior mechanical properties, but this can additionally result in stress shielding due to a modulus mismatch between the bone tissue and implanted device. Polymeric implants reduce this stress shielding effect but have much lower mechanical properties, limiting their use. Polylactic acid (PLA) is a widely used biodegradable thermoplastic polymer, however, its use has been limited by the polymer’s mechanical properties and rapid loss of strength during degradation in vivo. Polyether-ether-ketone (PEEK) is another common biocompatible polymer , with chemical and mechanical properties which make it a popular alternative …

End-Capping Star-Like Polycaprolactone With Different Functional Groups And The Interaction With Smooth Muscle Cells, Qingya Zeng

Masters Theses

Polycaprolactone (PCL) is a PDA-approved biodegradable polymer with excellent biocompatibility and flexibility. My work has been designed to find out how different functional end groups in star-like PCL samples affect the surface properties (such as hydrophilicity, morphology) and bulk properties (such as thermal, mechanical, rheological properties, and crystallization), and consequently the behavior and functions of primary rat aortic smooth muscle cells (SMCs).

I focused on the synthesis of PCL with different functional groups and their characterizations. In chapter 2, PCL samples with four or six hydroxyl end groups were synthesized with different molecular weights ranging from 8,000 to 30,000 g/mol …

Lignin Maximization: Analyzing The Impact Of Different Feedstocks And Feedstock Ratios Using Organosolv Fractionation, Marc Banholzer

Masters Theses

Over-exploitation of fossil fuels coupled with increasing pressure to reduce carbon emissions are prompting a transition from conventional petrochemical feedstocks to sustainable and renewable sourced carbon. The use of lignocellulosic biomass as a feedstock for integrated biorefining is of current high interest, as separation into its component parts affords process streams of cellulose, hemicellulose and lignin, each of which can serve as a starting point for the production of biobased chemicals and fuels. Given the large number of potential sources of lignocellulosic feedstocks, the biorefinery will need to adapt to the supplies available over a normal growing season. Of particular …

Development Of Lignin Carbon Fiber And Reinforced Composites, Nathan Kieran Meek

Masters Theses

The aim of this work is to develop lignin carbon fiber for composite applications. This included mechanical testing of single lignin carbon fiber (LCF), interfacial shear strength determination for LCF-resin systems using single fiber fragmentation, x-ray diffraction for the evaluation of microstructural parameters, and finally composite manufacturing and testing. Through these focused areas of analysis, the carbon fiber is thoroughly characterized and composite performance is evaluated. This effort was a collaboration with the Center for Renewable Carbon (CRC) and the Civil and Environmental Engineering Department. LCF produced by the CRC resulted in fibers having tensile strength of 250-800 MPa and …

Study Of Magneto-Optical Behaviors At A Ferromagnetic/Organic Semiconductor Interface, Jeremy Tyler Tisdale

Masters Theses

Organic materials have been widely studied for the last 20 years to use for photovoltaic applications. Organic photovoltaic materials have shown promising properties for solar cells, such as very low cost, flexibility, easy fabrication methods, etc. Although power conversion efficiencies for organic-based solar cells have exponentially grown in the last decade, up to about 13% in early 2016, it is still optimal to increase these efficiencies. In order to raise efficiencies, it is important to study the fundamental mechanisms inside organic materials that lead to photovoltaic properties. This thesis reports the magneto-optical effects on the p-type organic semiconductor, tetracene, from …

Radiation-Induced Radicals In Polyurea-Crosslinked Silica Aerogel, Benjamin Michael Walters

Masters Theses

Free radicals are atoms or molecules with an odd number of electrons in an outer shell. Since electrons typically occur in pairs, this leaves one electron that is unpaired. In seek of another electron to pair with, free radicals react with and steal electrons from neighboring molecules, which then become free radicals themselves. This can start a chain reaction, cascading into large scale damage.

Ionizing radiation can tear through molecules, just as bullets can tear through things that we see. If free radicals can be detected, and seen to increase in a material upon radiation exposure, this can indicate molecular …

Strength And Deformation Of “Tunable” Clay-Polymer Composites, Matthew David Bishop

Masters Theses

There are many different types of clay that exist throughout the world, and many are characterized by undesirable engineering properties. Soil improvement techniques are often implemented on these soils such as solidification, reinforcement, etc. However, these solutions are a “static” approach, as the soil’s properties cannot be modified over time. The development of the specific clay-polymer composites used in this study was motivated by the idea of creating a geomaterial that could be modified over time by adjusting its fabric, namely in the form of controlling interparticle and interlayer spacings. Therefore, the composites that are used in this study are …

Pretreatment And Pyrolysis Of Rayon-Based Precursor For Carbon Fibers, Kokouvi Akato

Masters Theses

In this work, two rayon fibers were investigated as carbon fiber precursors. A detailed consideration has been applied to a domestically produced cellulose fiber to carbon fiber (CF) transition. This transition of precursor to carbon fiber can be subdivided into two stages: pyrolysis (thermal decomposition) of cellulose in air and high temperature treatment in an inert atmosphere. The specific objectives were to investigate the stabilization stage of the produced rayon with respect to changes taking place during thermal decomposition, and to evaluate the effects on the properties of the carbonized fiber. Changes taking place during the conversion process of the …

Thermodynamic Analysis Of Polyethylene Glycol Thiol-Ene Click Chemistry And Surface Modification Of Bacterial Cellulose, Kaan Serpersu

Masters Theses

Polyethylene glycol (PEG) has been one of the extensively studied polymers for medical applications. However, the use of PEG can require complicated and low efficiency reactions which can impose limits to potentially useful medical solutions. Click chemistry has recently emerged as a way to avoid these pitfalls by utilizing reactions that are highly efficient and require simple reaction conditions. One such reaction is known as the Michael-addition thiol-ene click reaction (TECC). The combination of PEG with TECC has received some study, but has not been thermodynamically characterized as a click reaction. In this work PEG-TECC reaction kinetics were studied by …

Mesophase Pitch-Based Carbon Fiber And Its Composites: Preparation And Characterization, Chang Liu

Masters Theses

The objective of this study is to investigate the relationship among process, structure, and property of the UTSI pitch-based carbon fibers and optimize carbon fiber’s mechanical properties through the stabilization process. Various analysis techniques were employed throughout these investigations which include the Scanning Electron Microscope (SEM), optical microscope, Dia-stron system, MTS, and ImageJ.

Several fiber process techniques including fiber spinning, stabilization, and carbonization were explored to determine the effect of the thermal process on the fiber yield, fiber diameter, the sheath-core structure of stabilized fibers, the pac-man and hollow core structures of carbonized fibers, and the resulting mechanical properties of …

Formation And Characterization Of Polymerized Supported Phospholipid Bilayers And The In Vitro Interactions Of Macrophages And Fibroblasts., Jonathan Michael Page

Masters Theses

Planar supported, polymerized phospholipid bilayers (PPBs) composed of 1,2-bis[10-(2’,4’-hexadienoyloxy)decanoyl]-sn-glycero-3-phosphocholine (bis-SorbPC or BSPC) were generated by a redox polymerization method. The PPBs were supported by a silicon substrate. The PPBs were characterized and tested for uniformity and stability under physiological conditions. The PPBs were analyzed in vitro with murine derived cells that are pertinent to the host response. Cellular attachment and phenotypic changes in RAW 264.7 macrophages and NIH 3T3 fibroblasts were investigated on PPBs and compared to bare silicon controls. Fluorescent and SEM images were used to observe cellular attachment and changes in cellular behavior. The PPBs showed much lower …

Methods For Characterizing Mechanical Properties Of Wood Cell Walls Via Nanoindentation, Yujie Meng

Masters Theses

Nanoindentation is a method of contacting a material whose mechanical properties are unknown with another material whose properties are known. Nanoindentation has the advantage of being able to probe a material’s microstructure while being sensitive enough to detect variations in mechanical properties. However, nanoindentation has some limitations as a testing technique due to the specific formation and structure of some biomaterials. The main objective of this research is to identify any factors that influence the nanoindentation measurement of wood cell walls (a typical biomaterial).

The function of the embedding media in describing the properties of wood cells is poorly understood. …

Developing Chitosan-Based Biomaterials For Brain Repair And Neuroprosthetics, Zheng Cao

Masters Theses

Chitosan is widely investigated for biomedical applications due to its excellent properties, such as biocompatibility, biodegradability, bioadhesivity, antibacterial, etc. In the field of neural engineering, it has been extensively studied in forms of film and hydrogel, and has been used as scaffolds for nerve regeneration in the peripheral nervous system and spinal cord. One of the main issues in neural engineering is the incapability of neuron to attach on biomaterials. The present study, from a new aspect, aims to take advantage of the bio-adhesive property of chitosan to develop chitosan-based materials for neural engineering, specifically in the fields of brain …

Effect Of Chemicals And Binders On The Durability Of Flame Retardant Treated Cotton Nonwovens, Hatice Mercimek

Masters Theses

Cotton based highloft nonwovens have been used in consumer goods such as pillows, upholstered furniture and mattresses for years. Cotton provides comfort, soft hand and cost effectiveness to these products. In contrast to its desirable properties, cotton products have a higher proneness to burning and are characterized as highly flammable materials. During the last decade, the fire safety has been an important issue, and there has been increasing focus on approaches to reduce hazardous fire risks and effects. Incorporating flame resistant (FR) chemicals and fibers is one of the most effective methods to improve thermal resistance of cotton to ignition, …

Novel Design Of A Portosystemic Shunt Occluder, Tommy Lee Washington

Masters Theses

In some breeds of dog, specifically the Yorkshire Terrier, a genetic defect exists that causes a hepatic portosystemic shunt to form. A hepatic portosystemic shunt is a vessel that when present cause blood to bypass the liver, which is responsible for filtering waste from the digestive system and moving it out of the body. An implantable polymeric device was constructed that would slowly occlude the hepatic portosystemic shunt and force the blood to stop flowing through the bypassing vessel and flow through the vessel to the liver over 3-4 months time.

The portosystemic shunt occluder device consist of three polyoxymethylene …

Study Of Uv Curable Rubber-Toughened Epoxy Systems, Abhijeet A. Godbole

Masters Theses

Rubber-toughened epoxy resins are used extensively in various structural applications. Current thermal curing processes limit the possible structural designs and require higher inputs in terms of pressure, temperature and time. UV and electron beam curing offers almost instantaneous curing of even complex structural shapes using minimal inputs. Various formulations were quenched from single phase at high temperatures to various temperatures below the corresponding cloud point temperatures, before being allowed to cool to room temperature. These quenched formulations were then cured using UV and thermal energy. The cured material toughness increases with decreasing particle size by over 150%. The rate of …