Polymer and Organic Materials Commons^™

Structure And Properties Of Cnt Yarns And Cnt/Cnf Reinforced Pan-Based Carbon Fibers, Nitilaksha Phalaxayya Hiremath

Doctoral Dissertations

There is continuing effort to enhance the strength and modulus of carbon fibers by various combinations of materials and processing. Carbon fibers are produced from various precursors, and the strength of the CFs are directly related to the type of precursor used to make them. Carbon Nanotubes (CNTs) have received a great deal of attention due to their unique structure and properties. Major focus of this research is on the evaluation of processing, structure and properties of CNT based yarns and composite fibers.

High strength and low cost carbon fibers (CFs) are needed for today’s applicatio ns. A low cost …

Strategies For Controlling Bulk Heterojunction Morphology, Zach Daniel Seibers

Doctoral Dissertations

Organic photovoltaic devices have been extensively studied as a means to produce sustainable energy. However, the performance of organic-photovoltaic (OPV) devices is dependent upon a number of factors including the morphology of the active layer, device architecture, and processing conditions. Recent research has indicated that fullerenes in the bulk heterojunction are entropically driven to the silicon and air interfaces upon crystallization of P3HT, which occurs during thermal annealing. The first chapter of this research focuses on investigating the structure and function of end-tethered poly(3-hexylthiophene) chains to a transparent electrode as an anode buffer layer. Neutron reactivity reveals that these P3HT …

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 …

Interaction Between Charge-Transfer States Studied By Magnetic Field Effects, Mingxing Li

Doctoral Dissertations

Organic semiconducting materials, consisting mostly of carbon and hydrogen atoms, provide remarkable promise for electronic applications due to their easy processing, chemical tenability, low costs and environmental-friendly characteristics. For realizing electronic applications such as light emitting diodes and photovoltaic cells, charge-transfer states act as an important intermediate state for recombination and dissociation. Interestingly, magnetic field effects on semiconducting materials have been realized based on the suppression of spin mixing in the charge-transfer states. Although lots of studies have been carried out on investigating the properties of charge-transfer states, little has been done to consider the interaction between them. This thesis …

Exploring Thermoelectric Effect Based On Multi-Layer Conductor/Organic/Conductor Devices, Qing Liu

Doctoral Dissertations

Thermoelectric phenomena involve the simultaneous presence of both electrical and thermal currents. The entropy has been heavily used as the driving force to diffuse charge carriers between high and low temperature surfaces towards the development of Seebeck effects in thermoelectric devices. However, this driving force from entropy difference can cause an inverse relationship between Seebeck coefficient and electrical conductivity in the thermoelectric developments. Increasing the charge density can decrease the entropy difference to diffuse the charge carriers at a given temperature difference and lead to a decrease on the Seebeck coefficient developed by the entropy difference. Therefore, it is necessary …

Magnetic, Optical And Electrical Properties Of Electron-Hole Pairs In Polymer And Organo-Metal Halide Perovskite Photovoltaic Cells, Yu-Che Hsiao

Doctoral Dissertations

Organic polymer and organo-metal halide perovskite (OMHP) materials have attracted extensive attention during the past decade due to their various applications, like solar cells, light emitting diode, even lasing action (OMHP). Especially, the organo-metal halide perovskite solar cell shows a remarkable power conversion efficiency of about 20%, which is comparable to the amorphous silicon solar cell. Therefore, OMHP solar cell had been considered as a promising substitution for the next generation of renewable energy source. The OMHP materials contain both advantages of organic and inorganic semiconductors, like solution processable thin film fabrication, long-range ambipolar transport characteristics, high dielectric constants, low …

Inter-Droplet Membranes For Mechanical Sensing Applications, Nima Tamaddoni Jahromi

Doctoral Dissertations

This dissertation combines self-assembly phenomena of amphiphilic molecules with soft materials to create and characterize mechanoelectrical transducers and sensors whose sensing elements are thin-film bioinspired membranes comprised of phospholipids or amphiphilic polymers. We show that the structures of these amphiphilic molecules tune the mechanical and electrical properties of these membranes. We show that these properties affect the mechanoelectrical sensing characteristic and range of operation of these membrane transducers. In the experiments, we construct and characterize a membrane-based hair cell embodiment that enables the membrane to be responsive to mechanical perturbations of the hair. The resulting oscillations of membranes formed between …

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 …

Graphene And Carbon Nanotube Pla Composite Feedstock Development For Fused Deposition Modeling, Austin Plymill, Robert Minneci, Duncan Alexander Greeley, Jack Gritton

Chancellor’s Honors Program Projects

No abstract provided.