Materials Science and Engineering Commons^™

Effect Of Carbon Nanofiber-Matrix Adhesion On Polymeric Nanocomposite Properties—Part Ii, Khalid Lafdi, William Fox, Matthew Matzek, Emel Yildiz

Chemical and Materials Engineering Faculty Publications

A successful integration of two independent phases with good adhesion is imperative for effective translation of superior carbon nanofiber filler properties into a physically superior carbon nanocomposite. Carbon nanofibers were subjected to electrochemical oxidation in 0.1 M nitric acid for varying times.

The strength of adhesion between the nanofiber and an epoxy matrix was characterized by flexural strength and modulus. The surface functional groups formed and their concentration of nanofibers showed a dependence on the degree of oxidation. The addition of chemical functional groups on the nanofiber surface allows them to physically and chemically adhere to the continuous resin matrix. …

Carbon Nanoadditives To Enhance Latent Energy Storage Of Phase Change Materials, Shadab Shaikh, Khalid Lafdi, Kevin P. Hallinan

Chemical and Materials Engineering Faculty Publications

Latent energy storage capacity was analyzed for a system consisting of carbon nanoparticlesdopedphase changematerials (PCMs). Three types of samples were prepared by doping shell wax with single wall carbon nanotubes(SWCNTs), multiwall CNTs, and carbon nanofibers. Differential scanning calorimetry was used to measure the latent heat of fusion. The measured values of latent heat for all the samples showed a good enhancement over the latent heat of pure wax. A maximum enhancement of approximately 13% was observed for the wax/SWCNT composite corresponding to 1% loading of SWCNT. The change in latent heat was modeled by using an approximation for the intermolecular …

Nitrogen And Hydrogen Plasma Treatments Of Multiwalled Carbon Nanotubes, John G. Jones, A. R. Waite, Christopher Muratore, Andrey A. Voevodin

Chemical and Materials Engineering Faculty Publications

This article investigates plasma treatment of vertically aligned multiwall carbon nanotube (CNT) films in different plasma environments for modification of surface chemistry and morphology. The surfaces of the CNTs were functionalized with a pulsed dc plasma treatment, where the power was directly applied to the nanotube film in low pressure argon/nitrogen and argon/hydrogen backgrounds. Optical emission spectroscopy was used to detect atomic and molecular excitations in the gas mixtures as well as in pure gases in the vicinity of the CNT films. In situx-ray photoelectron spectroscopy was performed on the treated samples to examine CNT surface chemistry after treatment. …

Signaling Pathways Activated By Interleukin-2 And Interluekin-4 Receptors Mediate T Lymphocyte Clonal Expansion, Kristen K. Comfort

Chemical and Materials Engineering Faculty Publications

Cells sense and respond to chemical and physical stimuli through signal transduction pathways, which mediate cell proliferation, differentiation, migration, and survival. The cytokines interleukin-2 (IL-2) and interleukin-4 (IL-4) are key regulators of the adaptive immune system, particularly influencing the clonal expansion and differentiation of T cells. At least in culture, both synergistic and antagonistic effects of IL-2 and IL-4 co-stimulation have been reported; the antagonism, when observed, is thought to arise from the utilization of a common subunit shared by IL-2 and IL-4 receptors. We have sought to characterize IL-2 and IL-4 signaling at the level of intracellular pathways activated …

Impact Of A Microwave Curing Process On Tensile Strength Of Selected Carbon Fiber Composites, Brian B. Balzer

All-Inclusive List of Electronic Theses and Dissertations

The traditional process for curing carbon fiber (CF) composites has been the autoclave system. A review of recent research indicates curing CF composites in a microwave oven has the potential for reducing processing time. The problem statement of the experimental study was that the impact of a microwave curing process on tensile strength of selected CF composite specimens was unknown. The research study describes the statistical procedure and analysis of data to answer the specific question for the experimental trials: What is the effect on the tensile strength of cured CF composite samples due to the relationship of the autoclave …

High Temperature Degradation Of 5250-4 Polymer Resin, Patrick E. Link

Theses and Dissertations

5250-4 bismaleimide resin is used in high performance polymer matrix composites with high temperature aeronautical applications. This thesis investigated the thermal and oxidative degradation of 5250-4 neat resin powder in argon, air, and oxygen environments. The powder was aged at 163 deg. C, 177 deg. C, and 190 deg. C in all environments for at least 250 hours. Isothermal thermo-gravimetric analysis demonstrated that weight loss was negligible for aging in the argon environment, indicating weight loss is the result of an oxidative process at these temperatures. The 5250-4 powder exhibited an initial period of weight gain before eventually losing weight …

Microstructures And Viscoelastic Properties Of Anisotropic Magnetorheological Elastomers, Lin Chen

Articles

The microstructures and viscoelastic properties of anisotropic magnetorheological elastomers were investigated in this paper. The measurement results show that their mechanical properties are greatly dependent on the magnetic flux density applied in preparation. A finite-column model was proposed to describe the relations between the microstructures and the viscoelastic properties. The simulation results agree well with the experimental results.

Investigation On Magnetorheological Elastomers Based On Natural Rubber, Lin Chen

Articles

Magnetorheological Elastomers (MR Elastomers or MREs) are a kind of novel smart material, whose mechanical, electrical, magnetic properties are controllable under applied magnetic fields. They have attracted increasing attentions and broad application prospects. But conventional MREs are limited to wide applications because their MR effects and mechanical performances are not high enough. This paper aims to optimize the fabrication method and to fabricate good natural rubber based MREs with high modulus by investigating the influences of a variety of fabrication conditions on the MREs performances, such as matrix type, external magnetic flux density, and temperature, plasticizer and iron particles. Among …

Influence Of Van Der Waals Forces On Increasing The Strength And Toughness In Dynamic Fracture Of Nanofibre Networks: A Peridynamic Approach, Florin Bobaru Ph.D.

Department of Engineering Mechanics: Faculty Publications

The peridynamic method is used here to analyse the effect of van der Waals forces on the mechanical behaviour and strength and toughness properties of three-dimensional nanofibre networks under imposed stretch deformation. The peridynamic formulation allows for a natural inclusion of long-range forces (such as van der Waals forces) by considering all interactions as ‘long-range’. We use van der Waals interactions only between different fibres and do not need to model individual atoms. Fracture is introduced at the microstructural (peridynamic bond) level for the microelastic type bonds, while van der Waals bonds can reform at any time. We conduct statistical …

Thermal Conductivity Improvement In Carbon Nanoparticle Doped Pao Oil: An Experimental Study, Shadab Shaikh, Khalid Lafdi, Rengasamy Ponnappan

Chemical and Materials Engineering Faculty Publications

The present work involves a study on the thermal conductivity of nanoparticle-oil suspensions for three types of nanoparticles, namely, carbon nanotubes(CNTs), exfoliated graphite (EXG), and heat treated nanofibers (HTT) with PAO oil as the base fluid. To accomplish the above task, an experimental analysis is performed using a modern light flash technique (LFA 447) for measuring the thermal conductivity of the three types of nanofluids, for different loading of nanoparticles.

The experimental results show a similar trend as observed in literature for nanofluids with a maximum enhancement of approximately 161% obtained for the CNT-PAO oil suspension. The overall percent enhancements …

Experimental Study On The Influence Of Foam Porosity And Pore Size On The Melting Of Phase Change Materials, Khalid Lafdi, Osama Mesalam Mesalhy, Shadab Shaikh

Chemical and Materials Engineering Faculty Publications

Experimental study was carried out to study the phase change heat transfer within a composite of phase change material (PCM) infiltrated high thermal conductivity foam. An experimental setup was built to measure the temperature profiles and capture the melting evolution of the PCM inside aluminum foams. Aluminum foams were used as the porous material, and low melting temperature paraffin wax was used as the PCM. It was observed from the results that the system parameters of the wax/foam composite had a significant influence on its heat transfer behavior.

By using higher porosity aluminum foam, the steady-state temperature was reached faster …

Effect Of Carbon Nanofiber Heat Treatment On Physical Properties Of Polymeric Nanocomposites—Part I, Khalid Lafdi, William Fox, Matthew Matzek, Emel Yildiz

Chemical and Materials Engineering Faculty Publications

The definition of a nanocomposite material has broadened significantly to encompass a large variety of systems made of dissimilar components and mixed at the nanometer scale. The properties of nanocomposite materials also depend on the morphology, crystallinity, and interfacial characteristics of the individual constituents. In the current work, vapor-grown carbon nanofibers were subjected to varying heat-treatment temperatures.

The strength of adhesion between the nanofiber and an epoxy (thermoset) matrix was characterized by the flexural strength and modulus. Heat treatment to 1800C∘ demonstrated maximum improvement in mechanical properties over that of the neat resin, while heat-treatment to higher temperatures demonstrated a …

Heating Methods And Detection Limits For Infrared Thermography Inspection Of Fiber-Reinforced Polymer Composites, Jeff R. Brown, H. R. Hamilton

Publications

The use of fiber-reinforced polymer (FRP) composites to strengthen existing civil infrastructure is expanding rapidly. Many FRP systems used to strengthen reinforced concrete are applied using a wet lay-up method in which dry fibers are saturated on site and then applied to the surface. This research investigated using infrared thermography (IRT) as a nondestructive evaluation (NDE) tool for detecting air voids and epoxy-filled holes in FRP systems bonded to a concrete substrate. Four small-scale specimens with FRP thicknesses ranging from 1 to 4 mm (0.04 to 0.16 in.) containing fabricated defects were constructed and inspected in a laboratory setting. Three …

Interfacial And Capillary Pressure Effects On The Thermal Performance Of Wax/Foam Composites, Mohammad Rajab Almajali, Khalid Lafdi, Shadab Shaikh

Chemical and Materials Engineering Faculty Publications

A numerical investigation study was performed to study the phase change behavior of wax/foam composite encapsulated in an aluminum casing. Two types of foam materials, namely, aluminum and carbon, were infiltrated with paraffin wax. The progress of melt interface and temperature distribution within the encapsulated composite was analyzed using computational fluid dynamics software (CFD). A two-energy equation model was implemented in the CFD software through the use of user-defined function (UDF). Interfacial effects influencing the heat transfer process at the casing-composite junction and between the wax-foam surfaces within the composite were addressed through the use of separate UDF. In addition, …

Oxygen Plasma Treatment And Deposition Of Cnx On A Fluorinated Polymer Matrix Composite For Improved Erosion Resistance, Christopher Muratore, Andras Korenyi-Both, John E. Bultman, A. R. Waite, John G. Jones, T. M. Storage, Andrey A. Voevodin

Chemical and Materials Engineering Faculty Publications

The use of polymer matrix composites in aerospace propulsion applications is currently limited by insufficient resistance to erosion by abrasive media. Erosion resistant coatings may provide necessary protection; however, adhesion to many high temperature polymer matrix composite (PMC) materials is poor. A low pressure oxygen plasma treatment process was developed to improve adhesion of CNx coatings to a carbon reinforced, fluorinated polymer matrix composite. Fullerene-like CNx was selected as an erosion resistant coating for its high hardness-to-elastic modulus ratio and elastic resilience which were expected to reduce erosion from media incident at different angles (normal or glancing) relative to the …

An Evaluation Of Supercritical Drying And Peg/Freeze Drying Of Waterlogged Archaeological Wood, Eric Schindelholz, Robert Blanchette, Desmond C. Cook, Michael Drews, Steve Hand, Benjamin Held, Joel Jurgens, Betty Seifert

Physics Faculty Publications

This study was undertaken to evaluate the physical effects of drying waterlogged archaeological wood using supercritical carbon dioxide as compared to air drying and the popular polyethylene glycol (PEG)/freeze drying method. Previous studies have shown supercritical drying to be a potentially advantageous alternative to current methods of drying waterlogged wood through reduced processing time, minimal shrinkage, and increased success for reversibility. Samples in the form of blocks and planks of a few centimeters in size were prepared from two archaeological waterlogged wood sources and grouped into three treatment sets: one for air drying, one for PEG/freeze drying, and the other …

Intracellular Signaling Networks In The Immune Response: Pathways Activated By Interleukin-2 And-4 Receptors And Their Roles In T Cell Proliferation, Kristen K. Comfort

Chemical and Materials Engineering Faculty Publications

Cells sense and respond to chemical and physical stimuli through signal transduction pathways, which mediate cell proliferation, differentiation, migration, and survival. The cytokines interleukin-2 (IL-2) and interleukin-4 (IL-4) are key regulators of the adaptive immune system, particularly influencing the clonal expansion and differentiation of T cells. At least in culture, both synergistic and antagonistic effects of IL-2 and -4 co-stimulation have been reported; the antagonism, when observed, is thought to arise from the utilization of a common subunit shared by IL-2 and IL-4 receptors. We have sought to characterize IL-2 and IL-4 signaling at the level of intracellular pathways activated …

Control Of Plasma Flux Composition Incident On Tin Films During Reactive Magnetron Sputtering And The Effect On Film Microstructure, Christopher Muratore, Scott G. Walton, Darrin Leonhardt, Richard F. Fernsler

Chemical and Materials Engineering Faculty Publications

A hybrid plasma enhanced physical vapor deposition (PEPVD) system consisting of an unbalanced dc magnetron and a pulsed electron beam-produced plasma was used to deposit reactively sputtered titanium nitride thin films. The system allowed for control of the magnitudes of the ion and neutral flux, in addition to the type of nitrogen ions (atomic or molecular) that comprised the flux. For all deposition experiments, the magnitude of the ion flux incident on the substrate was held constant, but the composition of the total flux was varied. X-ray diffraction and atomic force microscopy showed that crystallographic texture and surface morphology of …

Friction And Adhesion In Rigid Surface Indentation Of Nitrile Rubber, Stephen Jerrams

Articles

When a rigid body in the form of a plane strain indentor is forced into an elastomer, the asperities on the surface of the indentor are filled by the softer material. As depth of ingress increases, the rubber displaced into the indentor asperities exhibits stick-slip behaviour. The rubber adheres to the rigid body and if the depth of ingress is held at a maximum, the level of adhesion remains constant despite short-term load relaxation occurring in the rubber.

This text describes the influence of a range of factors on indentation forces and adhesion in rigid indentation of hydrogenated nitrile rubbers. …

The Effects Of Humidity On The Dielectric Response In Ferroelectric Polymer Films Made By Langmuir-Blodgett Deposition, Kristin L. Kraemer, Alexander V. Sorokin, Christina M. Othon, Stephen Ducharme, Vladimir M. Fridkin

Stephen Ducharme Publications

No abstract provided.

Investigation Of Ferroelectricity In Newly Synthesized Nitrile Polymer Systems, Matt Poulsen, Stephen Ducharme, Alexander V. Sorokin, Sahadeva Reddy, James M. Takacs, Y. Wen, Jihee Kim, Shireen Adenwalla

Stephen Ducharme Publications

The ferroelectric and piezoelectric properties of newly synthesized polymer systems have been studied. To date PVDF and its copolymers P(VDF-TrFE) have provided the bulk of the knowledge pertaining to ferroelectricity in polymers. Recently, ultrathin ferroelectric films of P(VDF-TrFE) 70:30 have been fabricated using the Langmuir-Blodgett technique [4]. In this study, various new polymers have been synthesized by chemically altering the PVDF structure. This alteration was performed in order to enhance the amphiphilic nature of the polymer and thus improve the LB film quality and control. Various chemical groups have been used to replace the electropositive hydrogen and electronegative fluorine found …

Modeling And Simulation To Investigate Effects Of Static Mixer, Carrier Gas, Temperature And Pressure On The Mixing Ratio Of Carbon Nanotubes Growth Reactors, David Addie Noye

Dissertations and Theses @ UNI

The problem of this study was to investigate the effects of static mixer, carrier gas, carrier gas inlet pressures, and reactor operating temperatures on the mixing ratio of carbon nanotube synthesizing reactor. The methodology included design of static mixers, mathematical modeling, and computer modeling and simulation experiments.

The simulation experiment was performed based on single phase carrier gas modeling due to difficulty and time for three phase fluid modeling. First only nitrogen carrier gas in addition to the other three factors under constant inlet flow velocity and inlet temperature was simulated. Secondly, the same procedure was applied to argon carrier …

Method Of Making Wood-Based Composite Board, Laurent Malanda Matuana, Julia A. King

Michigan Tech Patents

A wood composite board or panel, such as particleboard, fiberboard, oriented strand board or waferboard and a method of producing the same. The composite board or panel comprises a plurality of wood pieces, thermoset resin to bind the wood pieces and a filler having a high thermal conductivity. Examples of such a filler include natural and synthetic graphites, metal, carbon, silicon carbide and other similar compounds and their mixtures.

Mapping Surface Polarization In Thin Films Of The Ferroelectric Polymer P(Vdf-Trfe)., Bradley W. Peterson, Stephen Ducharme, Vladimir M. Fridkin, Timothy J. Reece

Stephen Ducharme Publications

Pyroelectric Scanning Microscopy (PSM) has been developed to enable mapping of surface polarization in ferroelectric thin films, in particular the copolymer polyvinylidene fluoride trifluororethylene, or P(VDF-TrFE). The Chynoweth method for dynamically measuring pyroelectric current is employed in conjunction with a micropositioning system to construct two-dimensional images of the film polarization. These images have revealed enhancement of the polarization near the edges of the film below the average coercive field, with the center's polarization increasing thereafter to meet the edge value at saturation.

Electron Irradiation Effects On Ferroelectric Copolymer Langmuir-Blodgett Films, Christina M. Othon, Stephen Ducharme

Stephen Ducharme Publications

The effect of irradiation on the ferroelectric properties of Langmuir-Blodgett films of the copolymer poly(vinylidene fluoride-trifluorethelene) is investigating using 1.26 MeV electrons with dosages from 16 to 110 Mrad. Irradiation causes a systematic decrease in the phase transition temperature, coercive field and polarization of these thin films.

Ferroelectricity At Molecular Level, L. M. Blinov, A. V. Bune, Peter A. Dowben, Stephen Ducharme, Vladimir M. Fridkin, S. P. Palto, K. A. Verkhovskaya, G. V. Vizdrik, S. G. Yudin

Stephen Ducharme Publications

he synthesis of ultrathin ferroelectric nanostructures by the Langmuir-Blodgett method and their properties are reviewed. It is shown that ferroelectricity exists in one monolayer of the ferroelectric P(VDF-TrFE) copolymer, i.e., at the molecular level. The specific characteristics of switching of ultrathin ferroelectric films are established.

Etching With Electron Beam Generated Plasmas, D. Leonhardt, Scott G. Walton, Christopher Muratore, Richard F. Fernsler, R. A. Meger

Chemical and Materials Engineering Faculty Publications

A modulated electron beam generated plasma has been used to dry etch standard photoresist materials and silicon. Oxygen–argon mixtures were used to etch organic resist material and sulfur hexafluoride mixed with argon or oxygen was used for the silicon etching. Etch rates and anisotropy were determined with respect to gas compositions, incident ion energy (from an applied rf bias) and plasma duty factor. For 1818 negative resist and i-line resists the removal rate increased nearly linearly with ion energy (up to 220 nm/min at 100 eV), with reasonable anisotropic pattern transfer above 50 eV. Little change in etch rate was …

Effect Of Plasma Flux Composition On The Nitriding Rate Of Stainless Steel, Christopher Muratore, Scott G. Walton, D. Leonhardt, Richard F. Fernsler, David D. Blackwell, R. A. Meger

Chemical and Materials Engineering Faculty Publications

The total ion flux and nitriding rate for stainless steel specimens exposed to a modulated electron beam generated argon-nitrogen plasma were measured as a function of distance from the electron beam axis. The total ion flux decreased linearly with distance, but the nitriding rate increased under certain conditions, contrary to other ion flux/nitriding rate comparisons published in the literature. Variation in ion flux composition with distance was explored with a mass spectrometer and energy analyzer as a possible explanation for the anomalous nitriding rate response to ion flux magnitude. A transition in ion flux composition from mostly N2 1 to …

Synthysis Of Polymer/Nano-Droplet Composites From Reverse Microemulsion Polymerization, Liehui Ge

Master's Theses and Doctoral Dissertations

L₁ and L₂ domains of the water/AOT/MMA ternary system were investigated at 22±1°C. Free radical polymerizations were conducted in L₂ domain. Only opaque polymer rods were obtained. Acrylamide, a water soluble monomer, plays a role of co-surfactant which greatly expands the L₂ domain. However, polymerizations only yielded opaque material. SEM showed images of phase separation.

MDOS (2-Methacryloyloxy)ethyl trimethylammonium bis(2-ethylhexyl) sulfosuccinate, was synthesized by ion exchange method. L₁ and L₂ domains of the water/MDOS/MMA ternary system were also investigated at 22±1°C. Free radical polymerizations were conducted in L₂ domain. Transparent polymer was produced. The …

A Feasibility Study Of A Surface Modification Method For Polyolefin Plastics Formed By Injection Molding, David Brian Naughton

Master's Theses and Doctoral Dissertations

Polyolefin plastic (i.e. polypropylene, polyethylene, thermoplastic olefin i.e. TPO and blends) articles formed by injection molding have been found to have many useful applications. Many costly and/or hazardous methods are employed to increase the surface energy to a level that promotes the ability of a coating or adhesive to make intimate contact and thereby bond to the molded surface. The method described herein refers to a process that could eliminate the need for a post molding process such as solvent or waterborne adhesion promoting primers or expensive, hazardous surface treatment equipment by modifying the plastic surface during the injection molding …