Chemical Engineering Commons^™

Polymer Nanocomposites Containing High Aspect Ratio Particulates: Innovation In Co-Extruded Multilayer Barrier Films, Kevin Meyers

Dissertations

Delaminated montmorillonite (MMT) clay/ maleic anhydride grafted LLDPE nanocomposite multilayer films with alternating layers of LDPE were produced through multilayer co-extrusion. The MMT concentration within the nanocomposite layers was increased through annealing the films in the melt due to a mismatch in interdiffusion rates of the polymer layers. Analysis of the nanocomposite layers upon annealing revealed that the platelets impinged upon one another resulting in significant improvement in oxygen barrier in the multilayer system, exceeding the results of bulk nanocomposites.

Model analysis demonstrated that increasing the nanoplatelet aspect ratio or initial concentration in the filled layers would lead to even …

Combustion Of Nanocomposite Thermite Powders, Ian Monk

Dissertations

This work investigates combustion of nanocomposite thermite powders prepared by arrested reactive milling (ARM). The focus is on how ARM as a top-down approach to nano-thermite building generating fully-dense nanocomposite particles with dimensions of 1-100 µm affects the rates and mechanism of their combustion. A variety of thermites are milled using both aluminum and zirconium as fuels combined with several oxidizers (WoO₃, MoO₃, CuO, Fe₂O₃, and Bi₂O₃). The powders are ignited using both an electrostatic discharge (ESD) and a CO₂ laser beam.

A range of parameters vary …

Self-Generated Absorption Filter Based Optical Densitometry Calculations For Expanded Gamut And Spot Color Printing On Paperboard For Packaging Applications And Proposed Oba Index, Awadhoot Vijaykant Shendye

Dissertations

In the printing industry, process color printing is a very common way of reproduction of color photographic images. As continuous tone reproduction is not possible, images are converted to halftone format. Process control of a halftone image quality is carried out by measuring optical density of solid patches. ISO 5 defines measurement of optical density, formula, filters and requirements. As per ISO document optical density can be calculated only for the 4 colors cyan, magenta, yellow and black, known as process colors. To enhance quality of color reproduction of images, the number of reproducible colors are increased by gamut expansion. …

Formulation And Dissolution Of Polymer Strip Films For The Delivery Of Poorly Water-Soluble Drug Nanoparticles, Scott Matthew Krull

Dissertations

Polymer films have emerged as a promising platform for delivery of pharmaceutical products in recent years due to simplified processing, greater flexibility, and improved patient compliance over traditional solid dosage forms. However, the large majority of efforts have focused on incorporation of water-soluble drugs. The objective of this dissertation is to explore the robustness and versatility of the strip film platform for delivery of poorly water-soluble drug nanoparticles to ultimately develop a predictive model for drug release from such films.

The robustness of the polymer strip film platform to successfully deliver a variety of poorly water-soluble drug nanoparticles without the …

Co2 Reduction Over Noble Metal/Carbon Nanotube Catalyst, Yuan Zhu

Dissertations

Carbon nanotube-based Pt/Pd and Ru catalysts, independently synthesized by a microwave reaction technique, show good catalytic activity for CO2 reduction in the contexts of dry reforming (DR) of methane (CH₄ + CO₂ -> 2CO + 2H₂) and reverse water gas shift (RWGS) (H2 + CO₂ -> CO + H₂O). Reaction temperatures range from 773 to 973 K, with system pressure at 30 psig. The feed molar ratios CH4/CO₂ and CO₂/H₂ are varied from 0.5 to 2.0. Reactant conversions in DR and RWGS are strongly influenced by temperature and feed …

Assessment Of Nanocomposites Vs. Amorphous Solid Dispersions For Dissolution Enhancement Of Bcs Class Ii Drugs, Meng Li

Dissertations

Nanoparticle-based formulations (nanocomposites) and amorphous solid dispersions, shortly ASDs, are two major pharmaceutical formulation platforms used for the bioavailability enhancement of poorly water-soluble drugs. While they both have several advantages-disadvantages, a scientific comparative assessment of their drug release performance and dissolution mechanisms at different drug doses is not available. With the goal of addressing this issue, the dissertation aims to achieve three major objectives: (1) develop a processing-formulation understanding of wet media milling process for fast-efficient production of drug nanoparticles in stable nanosuspension form, (2) elucidate the impact of various classes dispersants on drug release rate and mechanisms during the …

Characterization Of Microporous Ectfe Membranes Exposed To Different Liquid Media And ?-Radiation And Nanoparticle Microfiltration Through Such Membranes, Na Yao

Dissertations

Microporous polymeric membranes are used in a variety of applications for separations, purification as well as barrier function. A major application is for microfiltration (MF). Changes in the properties of MF membranes exposed to acids, bases and organic solvents are of interest in semiconductor processing as well as in membrane contactor applications. Microfiltration membranes used for sterilization in beverage, biotechnology and pharmaceutical industries are sterilized by gamma radiation among others. Irradiation-induced degradation in membrane properties should be known. A variety of fluoropolymer-based microporous membranes are available with varying properties. Ethylene chlorotrifluoroethylene (ECTFE) membranes are a new addition and are of …

Cellulose Reinforced Thermoplastic Composites By In-Situ Ring-Opening Polymerization, Shahab Kashani Rahimi

Dissertations

Over the past two decades, the increasing concern about the negative environmental impacts of synthetic materials has led to rising interests in utilizing renewable natural resources to develop polymer materials with comparable properties and performance to their synthetic counterparts. One of the major fields of interest is polymer composites where the replacement of synthetic fibers with bio renewable natural fibers is of great potential. However, the processing difficulties, in terms of fiber dispersion and thermal stability have limited the application of cellulosic fibers to polymers with low processing temperatures which are mostly hydrophobic polymers. As a result, the true reinforcing …

Polyisobutylene Telechelic Prepolymers By In Situ End-Quenching And Post-Polymerization Modifications, Bin Yang

Dissertations

This volume focuses on the development of telechelic polyisobutylene (PIB) prepolymers by combining end-capping of living carbocationic polymerization of isobutylene (IB) with suitable reactants and post-polymerization modifications. Alkylation kinetics of PIB tert-chloride with alkoxybenzenes using either TiCl₄ or AlCl₃ were investigated. Quantitative para-position end-capped products were only achieved if the alkoxybenzene/AlCl₃ molar ratio was greater than unity; while no such molar ratio is required for TiCl₄, but the alkylation rate was slower than AlCl₃ under the same conditions. Photopolymerization kinetics analysis of PIB triphenol tri(meth)acrylates with low and high M_ns, …

Nanostructured Morphologies In Glassy Polymer Networks, Brian Greenhoe

Dissertations

The body of this work describes a novel approach for the dispersion of multi-walled carbon nanotubes in a high T_g epoxy prepolymer matrix using a twin screw high-shear continuous reactor. The method demonstrated improves on previous dispersion methods in several ways. It offers increased efficiency through excellent heat transfer, while being solvent-less, scale-able, and tailorable to drive dispersion states to judiciously chosen dispersion states. Furthermore, it was shown that dispersion state and agglomerate morphology can be directed, in several ways, through processing conditions and also by controlling the matrix viscosity profile through cure. Broadband dielectric spectroscopy, optical hot-stage microscopy, …

Design And Synthesis Of Dynamic Covalent Polymer Scaffolds With Controlled Architectures, Emily Annette Hoff

Dissertations

The design and synthesis of functional, controlled polymer architectures is essential to the development of new materials with precise and tailorable properties or applications. The work described in this dissertation focuses on the development of controlled polymer architectures with dynamic linkages for the design of multifunctional materials and surfaces via robust, efficient, and stimuli-responsive strategies.

In Chapter III, a post-polymerization modification strategy based on ambient temperature nucleophilic chemical deblocking of polymer scaffolds bearing N-heterocycle blocked isocyanate moieties is reported. Room temperature RAFT polymerization of three azole-N-carboxamide methacrylates, including 3,5-dimethyl pyrazole, imidazole, and 1,2,4-triazole derivatives, afforded reactive polymer scaffolds …

Processing Of Cds/Cdte Solar Cell And The Growth Model Of Cdte Thin Film, Guogen Liu

Dissertations

Cadmium telluride is the only thin film photovoltaic (PV) technology to surpass crystalline silicon PV in the cost. The most common CdTe solar cells consist of a simple p-n heterojunction structure containing a p-doped CdTe layer and n-doped cadmium sulfide (CdS) layer, which acts as a window layer. Cadmium Sulfide (CdS) thin films are often deposited on glass substrates coated with TCO layers by the close-spaced sublimation (CSS) or sputter techniques in industrial because of in-line production integration. It is seldom reported that CdS is deposited by the chemical bath deposition (CBD) batch process. The bottleneck of CBD for commercial …

Oxidation Kinetics Of Metallic Powders, Hongqi Nie

Dissertations

Aluminum and magnesium are widely used in pyrotechnic formulations and other energetic materials; they are also common components of reactive alloys, e.g., Al-Mg and B-Mg, and others, which are potential fuels for explosives and propellants. Reaction mechanisms and oxidation kinetics of aluminum, magnesium and Al-Mg alloy powders in different oxidizing environments are investigated using thermo-analytical measurements. New methods of data processing are developed, relying on measured particle size distributions of the reactive spherical powders. It became possible to identify the reaction interface location for many heterogeneous metal oxidation processes; for several reactions, detailed kinetic descriptions are obtained.

For aluminum powders, …

Experimental And Modeling Studies In Membrane Distillation, Lin Li

Dissertations

A variety of microporous hydrophobic flat sheet membranes of polyvinylidene fluoride (PVDF) and expanded-polytetrafluoroethylene (e-PTFE) are studied to evaluate the influence of membrane properties on their performance in desalination by direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD) processes. The membrane thickness is varied between 23 μm to 125 μm; the pore size is varied from 0.05 μm to 0.45 μm. The porosity is generally high in the range of 0.7 - 0.8. DCMD experiments are performed over a hot brine temperature range of 65 °C to 85 °C and distillate temperature at 25 °C for various brine …

Custom Engineered Nanomaterials For Energetics And Energy Applications, Ani Abraham

Dissertations

Recent interest in reactive material has shifted to more custom formulations targeting specific applications. In this work, preparation and characterization of nanomaterials used for several energetics and energy applications are addressed.

The main challenge of this effort is to design and prepare nanomaterials which have significant improvements associated with combustion dynamics, reaction rates, sensitivity, biocidal effectiveness, moisture stability, and are environmentally safer over the existing energetics. Nanomaterials that are used to defeat stockpiles of chemical and biological weapons, modify ionosphere properties for transmission of optical and radio signals, and for energy storage are prepared under room or cryogenic temperatures via …

3d Printed Bone Supplement Materials, Azem Khalifa Yahamed

Dissertations

Three-dimensional (3D) printing is an advanced rapid technology that can be used to make human bone substitutes with exact shape and designed structures, based on models created from actual individual bone medical Digital Imaging and Communications in Medicine (DICOM) images. Biocompatible polymers have been selected for 3D printing of human bone structures. The thermoplastics were 3D printed with Fused Deposition Modeling (FDM) are Acrylate Butadiene Styrene (ABS), Polylactic Acid (PLA) and ULTEM 9085 (a polyetherimide). The polyamide PA 2200 was 3D printed using Selective Laser Sintering (SLS). Digital ABS (a crosslinked acrylic polymer) was 3D printed using PolyJet Technology. These …

Laboratory Studies Of The Biodegradation Of Chemically Dispersed Oil: Effect Of Droplet Size And Nutrient Amendment, Christopher D'Ambrose

Dissertations

Oil spills could have devastating effects on the shorelines, and for this reason, chemical dispersants are commonly used to disperse the oil slick in the water column, preventing it from reaching the shorelines. However, the long term fate of dispersed oil depends on its biodegradation by indigenous microorganisms, which in turn depends on the concentration of nutrients in water and on the droplet size distribution.

Using water from the shorelines of Atlantic City, we placed the water with oil and dispersant inside EPA Baffled Flasks and placed them on rotatory shakers. We selected two speeds: high (250 rpm) and low …

Hybrid Aryl-Ether-Ketone And Hyperbranched Epoxy Networks, John Misasi

Dissertations

In this dissertation, relationships between chemical structures, cure kinetics and network architectures are correlated to bulk mechanical properties for novel, hybrid epoxy-amine networks. The work is split into two primary sections: the first is the synthesis and characterization of multifunctional glassy networks based on aryl-ether-ketone diamine curatives, while the second is based on the synthesis and characterization of hyperbranched epoxy polymers and their resulting networks.

Three aryl-ether-ketone (AEK) diamines of increasing molecular weights were synthesized and used to cure 4,4’-tetraglycidylether of diaminodiphenylmethane (TGDDM); the resulting networks were compared to 4,4’-diaminodiphenyl sulfone cured TGDDM. Architectural differences were created by varying cure …

Hydrodynamics, Dissolution, And Mass Transfer Effects In Different Dissolution Testing Apparatuses And Laboratory Systems, Bing Wang

Dissertations

Dissolution testing apparatuses and shaker flasks agitated by shaker tables are laboratory systems routinely found in many laboratories at most companies and agencies, and especially in pharmaceutical companies. These devices are commonly used in a number of applications, from drug development to quality control. Despite their common use, these systems have not been fully investigated from an engineering perspective in order to understand their operation characteristics. For example, the hydrodynamics of many of these systems have received little attention until relatively recently, and only over the last few years have some of these systems, such as the USP dissolution testing …

Molecular Modeling Of Sigma 1 And Sigma 2 Receptor Ligands: Pharmacophore Development And Comparison Using Discotech And Bioactivity Prediction Comparison Of Ab Initio And Density Functional Comfa Studies For Spiro And Other Receptor Ligands, Lisa M. Kardos

Dissertations

The role of the biological receptor is currently being studied by researchers in medicine. Information about sigma receptors in particular can be gained by studying the ligands associated with each type, sigma 1 or sigma 2. Sigma 1 receptor ligands consist of drug candidates that often have psychiatric and neurological applications; sigma 2 receptor ligands consist of drug candidates that have been linked with cancer treatment among other applications.

Molecular modeling of biological receptor ligands often encompasses pharmacophore development and Comparative Molecular Field Analysis (CoMFA). Pharmacophore models are developed to understand the unique features such as binding groups that make …

Lntegration Of Conventional Lithography And Printing Processes As A Key Enabling Technology For Printed And Flexible Sensing Systems, Binu Baby Narakathu

Dissertations

Sensors, which are used ubiquitously in a wide variety of applications, are revolutionizing the already ever-changing world we live in by providing real-time information about our surroundings. This dissertation focuses on the integration of conventional photolithography and printing processes as a key enabling technology for printed and flexible sensing systems.

Initially, an efficient opto-electrochemical sensing system, for the dual detection of heavy metal compounds was successfully developed. A novel microfluidic flow cell, with a reservoir volume of 25 μl, was designed and fabricated using acrylic. An electrochemical sensor with gold (Au) interdigitated electrodes (IDE) on a glass substrate was photolithographically …

Printing Functional Electronic Circuits And Components, Ahmed Tausif Aijazi

Dissertations

The purpose of this study was to investigate the challenges in printing reliable multilayer flexible circuits, devices and components. Gravure was used as the primary printing process for this work, but due to some limitations of gravure, other printing methods were also investigated. At first a systematic study was done to determine the optimum parameters for the gravure printing of sub 50 micron lines. Commercially available silver nanoparticle inks were printed on a lab scale gravure printer, Accupress®. The highest resolution line that was electrically conductive was 36μm wide. The 9μm, 18μm and 27μm lines were printed but were not …

Evaluation Of Environmental Materials As Thermal Witness Materials, Shashank Vummidi Lakshman

Dissertations

New and complex energetic materials are under development for achieving tunable pyrotechnical events for applications such as neutralization of biological weapons, bunker busters and many others. To guide the development of hybrid materials, the pyrotechnical environment they produce requires higher degree of characterization i.e. good description of spatial and temporal temperature distribution.

Temperature measurements in pyrotechnical events are especially challenging, where the temperature of the environment rises more than 2000 K on microseconds to few milliseconds time scale. These environments produce high thermal stress where traditional sensors like thermocouples, optical pyrometers struggle to describe the dynamic changes in the environment. …

Novel Scrubbing Systems For Post-Combustion Co2 Capture And Recovery, Tripura Mulukutla

Dissertations

Power plant emissions of flue gas releases considerable CO₂ to the atmosphere; CO₂ is considered to be the main contributor to global warming. Several gas absorption techniques are being investigated to reduce the capital and operating costs for CO₂ capture from post-combustion flue gas. Conventional method of CO₂ capture by an aqueous solution of monoethanolamine (MEA) and its subsequent stripping in a separate tower with steam at 120°C, is a highly energy intensive process. The low partial pressure of CO₂ in the flue gas inhibits the application of CO₂-selective membranes unless methods are …

Ignition Mechanism In Nanocomposites Thermites, Rayon Williams

Dissertations

Nanocomposite thermites (n-thermites) have been actively investigated for a wide range of potential applications including propellants, explosives, and pyrotechnics. There have been several recent efforts aimed at understanding ignition mechanisms of nanocomposite reactive materials. Although significant progress has been made, ignition mechanisms remain elusive. At the same time, a robust ignition model is required to incorporate these materials in practical energetic formulations. A challenge of this effort is to describe the mechanisms of ignition of n-thermites prepared by Arrested Reactive Milling (ARM) with different stimuli, including heat, spark and impact and also develop a multi-step kinetic model describing different processes …

Synthesis And Characterization Of Metal-Based Reactive Powders, Yasmine Aly

Dissertations

Aluminum added to propellants, explosives, and pyrotechnics, boosts their energy density. Different approaches were investigated that could shorten aluminum ignition delays, increase combustion rates, and decrease the tendency of aluminum droplets to agglomerate. Here, Al-based reactive, mechanically milled materials are prepared and characterized.

For powders with Fe, Ni, or Zn additives, the particles consist of an aluminum matrix and inclusions of Fe, Ni, or Zn comprising 10 at % of the bulk composition. For additives of Ni and Zn, only short milling times can be used to prepare composites; intermetallic phases form at longer milling times. Thermogravimetric analysis shows selective …

Improved Efficiency Organic Photovoltaic Cells Through Morphology Control And Process Modification, Qi Wu

Dissertations

Organic photovoltaic (OPV) cells have drawn great attention due to the potential to produce flexible, light weight, affordable solar cells using polymer organic photovoltaic materials; however, the current power conversion efficiency achieved for these systems is too low for widespread implementation of the technology. Morphology and phase separation are key factors determining the performance of organic photovoltaic cells. Precise control of the size and distribution of the phase-separated photoactive domains is necessary for optimum photon-electron conversion. Polyhedral oligomeric silsesquioxane (POSS) nanostructered chemicals have the potential to provide enhanced control of morphology, crystallinity, and phase dispersion in polymeric blend systems. In …

Fundamental Investigations Of Clay/Polymer Nanocomposites And Applications In Co-Extruded Microlayered Systems, Jeremy John Decker

Dissertations

The second and fourth generations of hydroxylated dendritic polyesters (HBP2, HBP4) were combined with unmodified sodium montmorillonite clay (Na+MMT) in water to generate a broad range of polymer clay nanocomposites from 0 to 100% wt/wt Na+MMT. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. It was shown that interlayer spacings were independent of generation number and changed over the composition range from 0.5 nm to 3.5 nm in 0.5 nm increments that corresponded to a flattened HBP conformation within the clay tactoids.

The HBP4/Na+MMT systems were investigated to study the …

Fluorine Containing Uv-Curable Materials For Advanced Transport Applications, James Thomas Goetz

Dissertations

The characterization of structure, thermal, gas transport, and free volume properties of two unique UV cured polymeric systems are studied and reported. In the initial pursuit of waterproof high water vapor transport membranes, it became apparent that the UV curing of fluorinated materials yielded routes to develop unique materials that fundamentally challenge conventional models for free volume and light gas transport behavior. UV-curing provides a means to rapidly “lock-in” morphologies that are accessible in the small molecule, monomer phase but rapidly become kinetically inaccessible when constraints such as covalent bonding and cross linking limit motion in the polymer system. This …

Integrating 3d Layered Manufacturing With Photonic Sintering, Precision Machining And Smart Coating Techniques For Rapid Casting Applications, Hemant Bohra

Dissertations

Developments in rapid casting technologies have led to a new era of inclusion of 3D printing. Three-Dimensional (3D) printing provides the flexibility and ease of reproducing a sand mold directly from CAD models, eliminating patterning steps, thus reducing the process time for creating prototypes. In addition to minimizing processing steps, 3D printing provides the advantages of higher precision and the ability to produce complex shaped sand molds, but it simultaneously possesses some limitations and concerns related to throughput, safety and logistics.

This study proposes an alternative method for creating sand molds by introducing a hybrid rapid prototyping approach to overcome …