Materials Science and Engineering Commons^™

Material Characterization And The Effects Of Moisture And Drying On Injection Molded Torlon 5030, Michael R. Di Re

Master's Theses

The effects of water absorption and drying were studied on injection molded Torlon 5030, a high performance thermoplastic fabricated by Solvay Specialty Polymers. Torlon 5030 contains 30% by weight glass fibers in a polyamide-imide base resin. The objective behind this work was to test and better define relevant properties for industrial applications using this material. While the material design guide offers information on many mechanical properties including tensile, fatigue, and creep data; there is little to no publicly published data on the effects of water absorption and any subsequent drying of Torlon 5030. Blistering was also studied. With exposure to …

Experimental Study Of Nanofiber Production Through Forcespinning, Simon Padron, Arturo Fuentes, Dumitru Caruntu, Karen Lozano

Mechanical Engineering Faculty Publications

A newly developed method of producing nanofibers, called forcespinning, has proven to be a viable alternative to mass produce nanofibers. Unlike electrospinning, the most common method currently being employed (which draws fibers through the use of electrostatic force), forcespinning utilizes centrifugal forces which allow for a host of new materials to be processed into nanofibers (given that electric fields are not required) while also providing a significant increase in yield and ease of production. This work presents a detailed explanation of the fiber formation process. The study is conducted using high speed photography to capture the jet initiation process at …

Structure And Properties Of Cocoons And Silk Fibers Produced By Attacus Atlas, Narendra Reddy, Yi Zhao, Yiqi Yang

Department of Textiles, Merchandising and Fashion Design: Faculty Publications

Silk fibers in the three layers of Attacus atlas (A. atlas) cocoons have morphological structure and tensile properties similar to that of Bombyx mori silk. Attempts are being made to produce silk for commercial applications from cocoons of relatively unknown wild insects due to the unique properties of the fibers and as a source of income and employment. In this research, A. atlas cocoons were used to study the chemical composition, morphology, physical structure and tensile properties of the silk fibers in the cocoons and ability of the fibers to support the attachment and proliferation of mouse fibroblast cells. It …

The Effect Of Microstructure On The Dynamic Equi-Biaxial Fatigue Behaviour Of Magnetorheological Elastomers, Yanfen Zhou, Stephen Jerrams, Tony Betts, Lin Chen

Conference Papers

Dynamic equi-biaxial fatigue behaviour of isotropic and anisotropic magnetorheological elas-tomers (MREs) based on a silicone rubber matrix was investigated using the bubble inflation method. Con-stant engineering stress amplitude was used as the control mode and samples were fatigued over different stress ranges between 0.75MPa and 1.4MPa. S-N (Wöhler) curves showing plots of stress amplitude (σa) ver-sus cycles to failure (N) are presented. Stress-strain behaviour throughout the fatigue process is described. Elastic modulus (E*) was studied for the specific cycles measured. It was found that anisotropic MREs exhi-bited greater fatigue resistance than isotropic MREs for a given magnetic particle content. Stress …

Infrared Optical Properties Of Amorphous And Nanocrystalline Ta2o5 Thin Films, Trevor J. Bright, J. I. Watjen, Zhuomin Zhang, Christopher Muratore, Andrey A. Voevodin, D. I. Koukis, David B. Tanner, Daniel J. Arenas

Chemical and Materials Engineering Faculty Publications

The optical constants of tantalum pentoxide (Ta 2O5) are determined in a broad spectral region from the visible to the far infrared. Ta 2O5 films of various thicknesses from approximately 170 to 1600 nm aredeposited using reactive magnetron sputtering on Si substrates. X-ray diffraction shows that the as-deposited films are amorphous, and annealing in air at 800 °C results in the formation of nanocrystallineTa 2O5. Ellipsometry is used to obtain the dispersion in the visible and near-infrared. Two Fourier-transform infrared spectrometers are used to measure the transmittance and reflectance at wavelengths from 1 to 1000 μm. The surface topography and …

Cross-Plane Thermal Properties Of Transition Metal Dichalcogenides, Christopher Muratore, Vikas Varshney, Jaime J. Gengler, Jianjun Hu, John E. Bultman, Timothy M. Smith, Patrick J. Shamberger, Bo Qiu, Xiulin Ruan, Ajit K. Roy, Andrey A. Voevodin

Chemical and Materials Engineering Faculty Publications

In this work, we explore the thermal properties of hexagonal transition metal dichalcogenide compounds with different average atomic masses but equivalent microstructures. Thermal conductivity values of sputtered thin films were compared to bulk crystals. The comparison revealed a >10 fold reduction in thin film thermal conductivity. Structural analysis of the films revealed a turbostratic structure with domain sizes on the order of 5–10 nm. Estimates of phonon scattering lengths at domain boundaries based on computationally derived group velocities were consistent with the observed film microstructure, and accounted for the reduction in thermal conductivity compared to values for bulk crystals.

Tannic Acid Coated Gold Nanorods Demonstrate A Distinctive Form Of Endosomal Uptake And Unique Distribution Within Cells, Emily A. Untener, Kristen K. Comfort, Elizabeth I. Maurer, Christin M. Grabinski, Donald A. Comfort, Saber M. Hussain

Chemical and Materials Engineering Faculty Publications

One of the primary challenges associated with nanoparticle-dependent biological applications is that endosomal entrapment in a physiological environment severely limits the desired targeting and functionality of the nanoconstructs. This study sought to overcome that challenge through a systematic approach of gold nanorod (GNR) functionalization: evaluating the influence of both aspect ratio and surface chemistry on targeted cellular internalization rates and preservation of particle integrity. Owing to their unique spectral properties and enhanced surface area, GNRs possess great potential for the advancement of nanobased delivery and imaging applications. However, their ability for efficient intracellular delivery while maintaining their specific physiochemical parameters …

Effect Of Microwave Heating On The Migration Of Additives From Ps, Pp And Pet Container Into Food Simulants, Ruoyin Cai

Theses

Microwave food packaging has become a tremendous element in the food manufacturing process. The purpose of any food packaging regulations concerned with the safety of the food is to control and limit the migration of substances from the packaging into the food. The main objective of this thesis is to test three different microwaving packaging materials that are the most common material in the market, viz. polystyrene (PS), polypropylene (PP), and polyethylene terephthalate (PET), migrated into four food simulant solutions. Four different simulant solutions were used based on the food type and FDA recommendations and regulations. These food simulants include …

Characterization Of And Controlling Morphology Of Ultra-Thin Nanocomposites, Guy C. Laine

Theses and Dissertations--Chemical and Materials Engineering

Ultrathin film nanocomposites are becoming increasingly important for specialized performance of commercial coatings. Critical challenges for ultrathin film nanocomposites include their synthesis and characterization as well as their performance properties, including surface roughness, optical properties (haze, refractive index as examples), and mechanical properties. The objective of this work is to control the surface roughness of ultrathin film nanocomposites by changing the average particle size and the particle volume fraction (loading) of monomodal particle size distributions. This work evaluated one-layer and two-layer films for their surface properties. Monodispersed colloidal silica nanoparticles were incorporated into an acrylate-based monomer system as the model …

Influence Of Surface Modification On Properties And Applications Of Complex Engineered Nanoparticles, Binghui Wang

Theses and Dissertations--Chemical and Materials Engineering

Complex engineered nanoparticles (CENPs) are being used on various applications. Their properties are different from those of neat nanoparticles. The dissertation explores these differences from four aspects: 1) Modify carbon nanomaterials’ inert surfaces and investigate the effect on thermal and rheological behavior of their dispersions; 2) Generate self-assembly bi-layer structure of oxide nanoparticles via surface modification; 3) Study interaction between lysozyme and different surface-charged ceria nanoparticles; 4) Investigate the biodistribution and transformations of CENPs in biological media.

An environment-friendly surface modification was developed to modify surfaces of carbon nanomaterials for increasing their affinity to non-polar fluid. It can offset formation …

Flexural Rigidity Characterization Of Retrofitted Frp Plates, Steven J. Makonis Jr., Stella B. Bondi, Zia Razzaq

Civil & Environmental Engineering Faculty Publications

Presented herein is a procedure and numerical results for flexural rigidity characterization of Fiber Reinforced Polymer (FRP) plates retrofitted with various types of fabrics. The FRP plates were retrofitted with Kevlar® 49 (Aramid), Carbon Fiber (Harness-Satin H5), and Unidirectional Carbon Fiber (T700 Aerospace Grade) fabrics, respectively. The FRP plate flexural rigidity values were calculated with a central finitedifference iterative scheme while utilizing the experimental load-deflection relations based on bending tests. The tests were performed on each plate by applying a concentrated load at the center. A fourth-order partial differential equation of plate equilibrium was adopted to estimate the plate flexural …

Silica Nanoparticle-Based Coatings With Superhydrophilic And Superhydrophobic Properties, Robert Andrew Fleming

Graduate Theses and Dissertations

Superhydrophilic and superhydrophobic surfaces have potential for implementation into a variety of fields, including self-cleaning surfaces, anti-fogging transparent materials, and biomedical applications. In this study, sandblasting, oxygen plasma treatments, silica nanoparticle films, and a low surface energy fluorocarbon film were employed to change the natural surface wettability of titanium, glass, and polyethylene terephthalate (PET) substrates, with an aim to produce superhydrophilic and superhydrophobic behavior. The effects of these surface modifications are characterized by water contact angles (WCAs), surface wetting stability, surface morphology and roughness, surface elemental composition, and optical transmittance measurements. The results show that stable superhydrophilic and superhydrophobic surfaces …

Design, Fabrication, Testing Of Cnt Based Isfet And Characterization Of Nano/Bio Materials Using Afm, Zhuxin Dong

Graduate Theses and Dissertations

A combination of Carbon Nanotubes (CNTs) and Ion Selective Field Effect Transistor (ISFET) is designed and experimentally verified in order to develop the next generation ion concentration sensing system. Micro Electro-Mechanical System (MEMS) fabrication techniques, such as photolithography, diffusion, evaporation, lift-off, packaging, etc., are required in the fabrication of the CNT-ISFET structure on p-type silicon wafers. In addition, Atomic Force Microscopy (AFM) based surface nanomachining is investigated and used for creating nanochannels on silicon surfaces. Since AFM based nanomanipulation and nanomachining is highly controllable, nanochannels are precisely scratched in the area between the source and drain of the FET where …

Prediction Of Compressive Creep Bhaviour In Flexible Polyurethane Foam Over Long Time Scales And At Elevated Temperatures, Conor Briody, Barry Duignan, Stephen Jerrams, Stephen Ronan

Articles

Compressive creep gradually affects the structural performance of flexible polymeric foam material over extended time periods. When designing components, it is often difficult to account for long-term creep, as accurate creep data over long time periods or at high temperatures is often unavailable. This is mainly due to the lengthy testing times and/or inadequate high temperature testing facilities. This issue can be resolved by conducting a range of short-term creep tests and applying accurate prediction methods to the results. Short-term creep testing was conducted on viscoelastic polyurethane foam, a material commonly used in seating and bedding systems. Tests were conducted …

Pulse Sharpening Effects Of Thin Film Ferroelectric Transmission Lines, Robert J. Sleezer

Graduate Theses and Dissertations

Advances in material science have resulted in the development of electrically nonlinear high dielectric thin film ferroelectrics, which have led to new opportunities for the creation of novel devices. This dissertation investigated one such device: a low voltage nonlinear transmission line (NLTL). A finite element simulation of ferroelectric transmission lines showed that NLTLs are capable of creating shockwaves. Additionally, if the losses are kept sufficiently low, it was shown that voltage gain should be possible. Furthermore, a method of accounting for material dispersion was developed. Results from simulations including material dispersion showed that temporal solitons might be possible from a …

Titanium Aluminum Nitride Films Deposited By Ac Reactive Magnetron Sputtering: Study Of Positioning Effect In An Inverted Cylindrical Magentron Sputtering System, George C. Vandross Ii

Graduate Theses and Dissertations

TiAlN films were deposited on glass substrates by AC magnetron sputtering at 2 kW with constant Argon and Nitrogen gas flow rates to study the effects of positioning on the deposited films. The deposition system used was an ICM-10 IsoFlux cylindrical magnetron sputtering chamber. The samples were placed in different positions and tilts with respect to the location of the Titanium and Aluminum targets in the chamber. It was found that with change in position and application of tilts, deposited films acquired different physical and chemical properties. It is believed that the differences in these properties were caused by to …

A Silicon Carbide Based Solid-State Fault Current Limiter For Modern Power Distribution Systems, Erik Darnell Johnson

Graduate Theses and Dissertations

The fault current limiter represents a developing technology which will greatly improve the reliability and stability of the power grid. By reducing the magnitude of fault currents in distribution systems, fault current limiters can alleviate much of the damage imposed by these events. Solid-state fault current limiters in particular offer many improved capabilities in comparison to the power system protection equipment which is currently being used for fault current mitigation. The use of silicon carbide power semiconductor devices in solid-state fault current limiters produces a system that would help to advance the infrastructure of the electric grid.

A solid-state fault …

P3ht:Pcpdtbt:Pcbm Multi- Polymer Single Layer Solar Cells, Ted Andreas

Physics

OPV efficiencies are limited by their narrow absorption; rather than using tandem architecture to overcome this obstacle, our group combined P3HT and PCPDTBT into a single layer BHJ solar cell that achieved 2.0% PCE. This is 33% higher than the pure P3HT control from this group, proving that multi-polymer solar cells have the potential to outperform their single-polymer components.

Biaxial Bending And Lateral-Torsional Instability Of Imperfect Frp I-Beams Including Effects Of Retrofitting, Jodi Marie Knorowski

Civil & Environmental Engineering Theses & Dissertations

This thesis presents the outcome of a theoretical and experimental study of the behavior of Fiber Reinforced Polymer (FRP) I-beams susceptible to lateral-torsional instability or when subjected to biaxial bending. Laboratory experiments involved application of vertical and horizontal static loads to a 4 x 4 x ¼ in. I-beam with various lengths, and the resulting displacement, twist, and strain were recorded. In the vertical direction, the beam was loaded from different reference load heights with respect to the shear center of the beam. The governing biaxial flexure and torsion differential equations were modified to account for the presence of initial …

Fabrication And Characterization Of Biocomposites From Polylactic Acid And Bamboo Fibers, Sarah E. Royse

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

Environmental concerns have been motivating research in the field of biodegradable materials, especially those from biological sources. Polylactic acid (PLA) is one biopolymer with the potential to replace some standard synthetic polymers. PLA is currently used for fibers, medical sutures, and some packaging, but is still used very little compared with synthetic polymers. One thing that can be done to expand the potential applications of PLA is to add fibers to create composite materials. Bamboo is a good choice for these fibers because it is abundant in many parts of the world, grows very quickly, and is widely unused. Composites …

Atomistic Simulations Of Defect Nucleation And Intralayer Fracture In Molybdenum Disulphide During Nanoindentation, James A. Stewart

Graduate Theses and Dissertations

Molybdenum disulphide (MoS2) is a layered, hexagonal crystal that has a very low coefficient of friction. Due to this low coefficient of friction, MoS2 has become a well-known solid lubricant and liquid lubricant additive. As such, nanoparticles of MoS2 have been proposed as an additive to traditional liquid lubricants to provide frictional properties that are sensitive to different temperature and pressure regimes. However, to properly design these MoS2 nanoparticles to be sensitive to different temperature and pressure regimes, it is necessary to understand the mechanical response of crystalline MoS2 under mechanical loading. Specifically, the fundamental mechanism associated with the nucleation …

Semiconductor Nanocrystals: From Quantum Dots To Quantum Disks, Zheng Li

Graduate Theses and Dissertations

The bottom-up colloidal synthesis opened up the possibility of finely tuning and tailoring the semiconductor nanocrystals. Numerous recipes were developed for the preparation of colloidal semiconductor nanocrystals, especially the traditional quantum dots. However, due to the lack of thorough understanding to those systems, the synthesis chemistry is still on the empirical level. CdS quantum dots synthesis in non-coordinating solvent were taken as a model system to investigate its molecular mechanism and formation process, ODE was identified as the reducing agent for the preparation of CdS nanocrystals, non-injection and low-temperature synthesis methods developed. In this model system, we not only proved …

Wireless Temperature Monitoring System For The Cal Poly Pilot Winery, Caitlin Devaney

Materials Engineering

This project, with an interdisciplinary group of two computer engineers and one materials engineer, was seeking to implement an automated temperature monitoring system which is affordable and easy to use, as well as adaptable to any arrangement and scale of a winemaker’s fermentation setup. My goal, as the materials engineer, was to design, fabricate, and test the enclosure, for the wireless nodes that are placed in the wine fermentation tanks, and the materials used for the node enclosure. For the enclosure of the system, materials selection was completed using CES software using limitations of only polymer materials which absorb less …

Blunt Impact Performance Evaluation Of Helmet Lining Systems For Military And Recreational Use, Jaclyn Siniora, Ryan Taylor, Darren Suey

Industrial Technology and Packaging

With the increasing problem in collegiate athletes experiencing injuries to the brain, different helmet liners where put to the test to see which liner provided athletes the greatest protection under specific conditions.

This senior project evaluates five different liners in football helmets. Each of the helmet liners were tested at three different temperatures: hot, cold, and ambient. Each helmet had seven different impact locations which were put to the test. The project was designed to be used to test ACH military combat liners as well. Due to shipping bottle necks the ACH combat liners have been left to future Cal …

Biaxial & Twist Testing Of Composite Carbon-Fiber Sandwich Panels For Automotive Racing Vehicles, Erik Eckberg

Materials Engineering

Composite sandwich panels were constructed with 4-ply plain weave carbon-fiber/epoxy face sheets in the 0^o/45^o/0^o/45^o orientation and 1/8^th inch Nomex honeycomb core. The panels were cut into 5-inch square test plates for mechanical testing. All testing was done on a fixture designed and fabricated by Pratt & Miller Engineering and installed on an Instron testing system at Cal Poly. The twist test was performed by supporting diagonal corners of the plate while simultaneously loading the opposite two corners at a crosshead rate of .06 in/min (ASTM 3044-94R11). Out of 10 panels tested, …

Artificial Alveolar-Capillary Membrane On A Microchip, Keith Male

Materials Engineering

A microfluidic device was synthesized out of polydimethyl siloxane (PDMS) to simulate the structure of the alveolar-capillary interface of the human lung. Soft lithography techniques were used to build a mold structure out of SU-8 epoxy at heights ranging from 30µm to 110 µm on a silicon substrate, with the 70 µm structure working the best. A mixture of 10:1 Sylgard 184 elastomer was then cast using the mold, and cured at a temperature of 80^oC. For the porous membrane, the PDMS was spun on at 6000rpm for 30 seconds using a spin coater to produce a membrane …

Bond Strength Characterization Of Su-8 To Su-8 For Fabricating Microchannels Of An Electrokinetic Microfluidic Pump, Nash Anderson

Materials Engineering

Photosensitive negative resist polymer layers of SU-8 2050 were adhered to 100 mm n-type silicon and Pyrex wafers via spin coating. These wafers were then bonded together at various temperatures of 100 ͦC, 120 ͦC, 140 ͦC, 150 ͦC, 160 ͦC, and 180 ͦC. The target thickness of each SU-8 layer was 100 µm. Photolithography was used to create microfluidic channels within the SU-8. An n-type silicon wafer and a Pyrex wafer, each with an SU-8 layer, were brought together on the “hard bake” or final step of SU-8 polymerization. A pressure of ~300 KPa was applied during the hard …

Multipolymer Interactions In Bulk Heterojunction Photovoltaic Devices, Grant Olson

Physics

Multipolymer photovoltaics, single layer devices made up of multiple photoactive polymers, can create organic photovoltaics (OPVs) with a wider spectral response than single polymer systems without the difficult fabrication of a tandem. Our group has successfully created multipolymer solar devices with 2% power conversion efficiency. We have analyzed the optical and electrical properties of these devices, and found that it may be possible for polymers to assist each other with charge extraction, though combining polymers disrupts single polymer crystallinity.

Effects Of Abrasive Particles On The Projected Fatigue Life Of Nylon Climbing Rope, Casey Johnson, Charlie Klonowski

Materials Engineering

When climbing rope is used outdoors, it is exposed to foreign particles such as sand and silt. These particles can potentially work their way through a rope’s sheath and damage the load bearing core decreasing the rope’s strength without exhibiting obvious wear. This project quantified the effect of abrasive particles on the fatigue life of nylon climbing rope. The experimental design involved 18 pieces of static nylon rope of kernmantle construction. 9 of these samples were heavy agitated in a slurry of water, silt, sand and soil, and left to sit for 24 hours. The remaining 9 samples were submerged …

Active Response Of Polymer Materials From External Stimuli – Solvents And Light; Grafting Reactions On Perovskite Layers, Jianxia Zhang

LSU New Orleans Theses and Dissertations

The active response of a series of polymeric materials was investigated. Both solvent activated and light activated thin films and wire systems show dynamic behaviors when exposed to different stimuli.

Solvent mediated fluxional behavior of polymer thin films involved extensive, rapid curling both on infusion and evaporation of good solvents. These films can be either lab-fabricated ones or commercial ones, and the curling behavior can be as fast as seconds. Conditions including polymer materials, chosen solvents, and film geometry can affect the behavior.

Methods that allowed for the creation and retention of distorted wire structures were also developed; the asymmetric …