Engineering Commons^™

Spray-Dried Cellulose Nanofibril-Reinforced Polypropylene Composites For Extrusion-Based Additive Manufacturing, Lu Wang

Electronic Theses and Dissertations

Compared to conventional manufacturing process, additive manufacturing (AM) offers free-form design, lighter and more ergonomic products, short lead time and less waste. Extrusion-based AM can be used to print thermoplastics. However, extrusion-based AM has processing challenges in printing semi-crystalline thermoplastics, for instance, polypropylene (PP). Cellulose nanofibrils (CNF) are one type of cellulose nanofibers that are produced from pulp fibers. CNF has extraordinary properties which make it an ideal candidate to reinforce polymers. Spray-dried CNF (SDCNF) is able to be incorporated into thermoplastic matrices without modifying conventional processing procedures.

The mechanical properties of 3D printed plastic parts have been considered significantly …

Cellulose Nanofiber-Reinforced Impact Modified Polypropylene: Assessing Material Properties From Fused Layer Modeling And Injection Molding Processing, Jordan Elliott Sanders

Electronic Theses and Dissertations

The purpose of this research was to investigate the use of cellulose nanofibers (CNF) compounded into an impact modified polypropylene (IMPP) matrix. A IMPP was used because it shrinks less than a PP homopolymer during FLM processing. An assessment of material properties from fused layer modeling (FLM), an additive manufacturing (AM) method, and injection molding (IM) was conducted. Results showed that material property measurements in neat PP were statistically similar between IM and FLM for density, strain at yield and flexural stiffness. Additionally, PP plus the coupling agent maleic anhydride (MA) showed statistically similar results in comparison of IM and …

Material Properties Design Using Simulations And Experiments For Powder Injection Molding Of Lead Zirconate Titanate (Pzt)., Bhushan Pramod Bandiwadekar

Electronic Theses and Dissertations

Powder injection molding (PIM) process simulations can be performed to minimize the number of injection molding experiments by estimating material properties necessary for PIM simulations. In current work, lead zirconate titanate (PZT) powder-polymer binder feedstock was compounded for 45 vol. % and 52 vol. % solids loading. PIM experiments on designed micro-pillar array geometry were performed using 52 vol. % PZT. Using PIM experiments results as basis, PIM simulations were performed on designed micro-pillar array geometries to understand the effectiveness of PIM simulations with the use of estimated feedstock properties in predicting molding behavior that have micro-features. Additionally, PIM simulations …

Artificial Olfactory System For Multi-Component Analysis Of Gas Mixtures., Alexander Aleksandrovich Larin

Electronic Theses and Dissertations

Gas analysis is an important part of our world and gas sensing technology is becoming more essential for various aspects of our life. A novel approach for gas mixture analysis by using portable gas chromatography in combination with an array of highly integrated and selective metal oxide (MOX) sensors has been studied. We developed a system with small size (7 x 13 x 16 inches), low power consumption (~10 W) and absence of special carrier gases designed for portable field analysis (assuming apriori calibration). Low ppb and even sub-ppb level of detection for some VOCs was achieved during the analysis …

Design, Analysis, And Application Of A Cellular Material/Structure Model For Metal Based Additive Manufacturing Process., Shanshan Zhang

Electronic Theses and Dissertations

Powder bed fusion additive manufacturing (PBF-AM) has been broadly utilized to fabricate lightweight cellular structures, which have promising potentials in many engineering applications such as biomedical prosthesis, aerospace, and architectural structures due to their high performance-to-weight ratios and unique property tailorabilities. To date, there is still a lack of adequate understanding of how the cellular materials are influenced by both the geometry designs and process parameters, which significantly hinders the effective design of cellular structures fabricated by PBF-AM for critical applications. This study aims to demonstrate a cellular structure design methodology that integrates geometrical design and process-material property designs. Utilizing …

Computational Prediction Of Conductivities Of Disk-Shaped Particulate Composites, Jian Qiu

Electronic Theses and Dissertations

The effective conductivities are determined for randomly oriented disk-shaped particles using an efficient computational algorithm based on the finite element method. The pairwise intersection criteria of disks are developed using a set of vector operations. An element partition scheme has been implemented to connect the elements on different disks across the lines of intersection. The computed conductivity is expressed as a function of the density and the size of the circular disks or elliptical plates. It is further expressed in a power-law form with the key parameters determined from curve fittings. The particle number and the trial number of simulations …

Liquid Gating Ptfe Membranes To Reduce Fouling, Jonathan C. Overton

Electronic Theses and Dissertations

In the processing industry, fouling due to the accumulation of bioparticles or bacteria on the surface of membranes results in decreased capacity, and subsequently requires filtration membranes to require periodic cleaning, causing increased operating costs. In this work, we evaluate the recently discovered concept of liquid-gated membranes (LGMs) in both filtration characteristics, as well as their ability to facilitate passive cleaning of membranes fouled with whey proteins. Additionally, we show that biofilms formed on the surface of these membranes can be removed through exposure to an air-water interface through a simple dipping step. We further analyze the mechanisms of fouling …

Feasibility Of Using 3d Printed Molds For Thermoforming Thermoplastic Composites, Sunil Bhandari

Electronic Theses and Dissertations

This thesis presents a novel combined experimental and numerical mechanics approach for characterizing 3D printed thermoplastic materials by the fused deposition modeling process for thermoforming thermoplastic composites. The implications of this work are:

1. a methodology for model-based performance evaluation of 3D printed structural parts, and
2. an improved design of 3D printed molds for composites manufacturing, which has potential for material innovations and scaled-up applications in additive manufacturing.

The thesis formulates basic criteria for selection of thermoplastic polymer used for the 3D printed mold based on forming temperatures. The thesis creates a lattice and shell finite element model of the 3D …

Development And Degradation Analysis Of Novel Micro And Nanostructured Transition Metal Oxide (Tmo) Anodes For Aqueous Sodium Ion Batteries., Santanu Mukherjee

Electronic Theses and Dissertations

One of the primary motivations driving battery technology research is the need to develop cleaner and more efficient energy storage systems. The portable electronics industry has developed exponentially, especially over the last couple of decades and therefore the importance of efficient electrochemical energy storage systems cannot be overstated. Li-ion batteries have been the predominant rechargeable energy in use, however, they have their own particular drawbacks viz. flammability of the electrolyte, expensive mining of the Li metal etc. This is where the importance of Na-ion batteries lie. This research focuses on using existing transition metal oxides (TMOs) and tuning their crystal …

Data Driven Discovery Of Materials Properties., Fadoua Khmaissia

Electronic Theses and Dissertations

The high pace of nowadays industrial evolution is creating an urgent need to design new cost efficient materials that can satisfy both current and future demands. However, with the increase of structural and functional complexity of materials, the ability to rationally design new materials with a precise set of properties has become increasingly challenging. This basic observation has triggered the idea of applying machine learning techniques in the field, which was further encouraged by the launch of the Materials Genome Initiative (MGI) by the US government since 2011. In this work, we present a novel approach to apply machine learning …

Carbon Nanotube (Cnt) Metallic Composite With Focus On Processing And The Resultant Properties, Md Muktadir Billah

Electronic Theses and Dissertations

Metal-carbon nanotubes (CNTs) composites are the promising advanced materials that are being developed to take the advantage of the exceptional properties of CNTs. Because of the intrinsically strong in-plane atomic SP2 bonding CNTs offer high young's modulus (1.0–1.8 TPa), high tensile strength (30–200 GPa) and high elongation at break (10–30%). The thermal conductivity of individual single-walled carbon nanotube (SWCNT) and multi-walled carbon nanotube (MWCNT) are about 6000 W/m-K and 3000 W/m-K, respectively. Therefore it is expected that by incorporation of CNTs in metal matrices multi-functional composites can be used ideally as thermal interface materials, light-weight high-strength structural materials, electric components, …

Electrode Integration Of Nanostructured Metal And Metal Oxide Materials Based On In-Situ Growth Methods For Environmental Sensors, Xiaochen Wang

Electronic Theses and Dissertations

In the past decades, increased human population and activities have introduced a large amount of pollutants into the environment. Various types of conventional analytical instruments were used for monitoring the emitted chemicals with low detection limit, high accuracy, and discrimination power. However, many of these methods are laboratory-based owing to sample collection, transportation, extraction, and purification steps. To make real-time on-site monitoring possible, miniaturized sensors with various integrated elements were developed. One of the most well-known strategies is to utilize nanostructured materials with enhanced sensing properties for those devices. For a majority of the current state of art devices, the …

Activated Carbon Preparation And Modification For Adsorption, Yuhe Cao

Electronic Theses and Dissertations

Butanol is considered a promising, infrastructure-compatible biofuel. Butanol has a higher energy content than ethanol and can be used in conventional gas engines without modifications. Unfortunately, the fermentation pathway for butanol production is restricted by its toxicity to the microbial strains used in the process. Butanol is toxic to the microbes, and this can slow fermentation rates and reduce butanol yields. Gas stripping technology can efficiently remove butanol from the fermentation broth as it is produced, thereby decreasing its inhibitory effects. Traditional butanol separation heavily depends on the energy intensive distillation method. One of the main issues in acetone-butanol-ethanol fermentation …

Bio Inspired Lightweight Composite Material Design For 3d Printing, Kaushik Thiyagarajan

Electronic Theses and Dissertations

Lightweight material design is an indispensable subject in product design. The lightweight material design has high strength to weight ratio which becomes a huge attraction and an area of exploration for the researchers as its application is wide and increasing even in every day-to-day product. Lightweight composite material design is achieved by selection of the cellular structure and its optimization. Cellular structure is used as it has wide multifunctional properties in addition to the lightweight characteristics. Applications of light weight cellular structures are wide and is witnessed in all industries from aerospace to automotive, construction to product design. In this …

Study Of Surface Passivation Behavior Of Crystalline Silicon Solar Cells, Haider Ali

Electronic Theses and Dissertations

To achieve efficiencies approaching the theoretical limit of 29.4% for industrially manufactured solar cells based on crystalline silicon, it is essential to have very low surface recombination velocities at both the front and rear surfaces of the silicon substrate. Typically, the substrate surfaces feature contacted and uncontacted regions, and recombination should be limited for both to maximize the energy conversion efficiency. Uncontacted silicon surfaces are often passivated by the deposition of silicon nitride (SiNx) or an aluminum oxide film with SiNx as capping layer (Al2O3/SiNx stack). Further, proper surface preparation and cleaning of Si wafers prior to deposition also plays …

Variable Oxidation & Defects In Ti-6al-4v Material In Electron Beam Melting Additive Manufacturing, Edward Patton Clark

Electronic Theses and Dissertations

Powder-based metal in additive manufacturing (AM) is advantageous for rapid prototyping of parts and components, with the benefit of reusing powder to reduce production costs. A common driver in the aerospace industry is free-form complex geometries which can be created using CAD software to optimize specifications with strength-to-weight ratios in components. Weight optimization of aircraft components using additive manufacturing reduces material, which significantly reduces production cost in comparison to cast and wrought metallic products. Large biomedical and aerospace industries heavily invest in feedstock metal powders that have low density under structural stresses and high temperatures, resulting in superior resistance to …

Computational Modeling Of Percolation Conduction And Diffusion Of Heterogeneous Materials, Jian Qiu

Electronic Theses and Dissertations

Heterogeneous materials provide a unique combination of desirable mechanical, thermal or electrical properties. This dissertation presents several micro-structure modeling approaches to predict the effective properties of heterogeneous materials and demonstrates its certain application toward two highly heterogeneous, unconventional structural composite materials (carbon fiber reinforced composite materials and graphene nanoplatelets composite). By using the efficient computational algorithm based on the FEA, a randomly oriented disk-shaped particles system are generated. A new element partition scheme based on the vector operations and geometry of inclusion has been implemented to mesh the intersected disks. The computed equivalent conductivity is expressed as a power-law function …

Phase Stability In Cobalt-Based L12 Quaternary Intermetallics From Density Functional Theory, William Earwood

Electronic Theses and Dissertations

The effects of higher order alloying additions (Mo, Ti, Ta, Hf, Fe, V) on the phase stability of L12 (γ’) intermetallics have been studied via first-principles. A 32 atom special-quasi-random structure was used to mimic the experimentally observed solid solution sublattice. Density of states distributions were generated in order to directly observe the impact of alloying additions on the position of the pseudogap and number of states at the Fermi level. Charge density differences across the supercell were visualized to analyze changes in bonding behavior. The results indicate that substitutions of Ti, Ta, and Hf in place of the central …

Dynamic Analysis For Characterization Of Novel Biomass Based Composities, Aarsh Jigish Shah

Electronic Theses and Dissertations

Resources from forests constitute a significant asset of Mississippi State. Forests cover around 19.7 million acres (65%) of the total land area of Mississippi. Total annual economic impact of Mississippi’s forest products is about $17 billion. Creation of high-value products will lead to a number of economic benefits to the region. This work focuses on the study of bio-composite. Bio-composite materials are a ‘Green’ alternative to conventional materials which are readily recyclable and biodegradable. Taylor made properties are achievable in bio-composites, this being one of the significant advantages. Producing biodegradable products has become a necessity due to petroleum-based products being …

Interaction Between Carbon Nanotubes And Metals (Al, Cu) And The Effects On Resultant Properties Of The Hybrid Materials, Jingyin Jiang

Electronic Theses and Dissertations

Due to the exceptional strength, stiffness and excellent electrical and thermal properties, carbon nanotubes (CNTs) have been regarded as promising candidates for advanced nanoelectronics and multifunctional nanocomposites. In this dissertation, the interaction of CNTs with metals have been investigated and the resultant electrical conduction have been analyzed, aiming to develop innovative avenues to best utilize CNTs' potential. In order to do so, quantum mechanics calculations have been carried out to study that how to obtain greater electrical conduction by doping metals (Cu, Al) which tailor the electronic structure of three different types of metal-CNT interactions, : 1) encapsulation of atoms …

Printable Carbon Nanotube Based Multifunctional Nanocomposites For Strain Sensing And Self-Heating, Xin Wang

Electronic Theses and Dissertations

The unique properties of carbon nanotubes (CNTs) represent a potential for developing a piezo-resistive strain sensor and a resistive heating sheet with a smart structure. Conventional fabrication techniques of CNT based nanocomposites such as molding, casting or spray coating lack the ability to control the geometry and properties of fabricated composites. In order to meet the various requirements of strain sensing or self-heating applications, nanocomposites with complex geometry and controllable properties are in high demand. Digital printing technique is able to fabricate CNT films with precisely controlled geometry with the help of computer aided design, and their properties could also …

Band Gap Engineering Of Titania Systems Purposed For Photocatalytic Activity, Cameron Robert Thurston

Electronic Theses and Dissertations

Ab initio computer aided design drastically increases candidate population for highly specified material discovery and selection. These simulations, carried out through a first-principles computational approach, accurately extrapolate material properties and behavior. Titanium dioxide (tio2) is one such material that stands to gain a great deal from the use of these simulations. In its anatase form, titania (tio2) has been found to exhibit a band gap nearing 3.2 ev. If titania is to become a viable alternative to other contemporary photoactive materials exhibiting band gaps better suited for the solar spectrum, then the band gap must be subsequently reduced. To lower …

Control Of Pore Characteristics Of Porous Silicon Using Non-Toxic Electrochemical Etching For Photovoltaics And Supercapacitor Applications, Utpal Saha

Electronic Theses and Dissertations

Porous silicon has exhibited lower reflectance and higher surface area than the pristine silicon. This property of porous silicon can be applied to photovoltaic (PV) application for more efficient silicon solar cells and for higher performance of supercapacitors. NH4Fl electrolytic etching solution has been used to fabricate porous silicon, but the control of pore morphology of silicon is achieved only by controlling the time. Therefore, it is urgently required to use other etching parameters such as voltage and current to achieve flexible control of pore properties. Porous silicon can also be used to fabricate supercapacitors. An established approach to make …

Development Of Highly Sensitive And Selective Breathing Sensors Using Molecular Imprinted Filtering For Diabetic And Alcoholic Patients, Md. Saleh Akram Bhuiyan

Electronic Theses and Dissertations

Wellness sensor technology is an emerging diagnostic test research field, which mostly deal with the point of care of the patients in the recent days. Due to the lack of awareness from the patients, most diseases cannot be detected in due time. This led to worse conditions, such as diabetic and alcoholic syndrome. Therefore, many research groups have been working to develop portable sensor devices that can track serious diseases. These include diabetic and alcoholic biomarkers in breathing. These devices have very high selectivity and reliability. However, the major limitation of biomarkers is that it deals with the bio-molecular based …

Advanced Carbon Materials Based Electrodes For High Performance Symmetric Supercapacitors, Keliang Wang

Electronic Theses and Dissertations

Supercapacitors have received considerable attention due to their high energy density, long life time, rapid charge/discharge rate, and because they are environmental friendly technology. Electrode materials play a key role in the final performance of supercapacitors. Carbon, usually used as symmetric supercapacitors electrode materials, exhibit extraordinary stability in harsh electrolyte and electrochemical performance owing to its physical and chemical properties. In addition, porous structure originated from activation, excellent electrical conductivity, sustainability, wide availability and low cost further offering the improvement in electrochemical performance and make it to be a promising electrode material for symmetric supercapacitors. Considering the factors affected electrochemical …