Home > Seminars > Spring 2008 Seminar Series
SPRING 2008 SEMINAR SERIES
Time: Fridays, 2:00 p.m. - 3:30 p.m.
Location: Aggarwal Lecture Hall, Room 130
Polymer Engineering Academic Center
250 South Forge Street, Akron, OH 44325-0301
Lectures Are Free And Open To The Public
Click here to print the schedule
Date |
Topic / Speaker |
Jan. 18 |
"Impact of Composite Structures" |
Jan. 25 |
No Seminar |
Feb. 1 |
"Electronic Structure of Conductive Interfaces: Molecular Level Insights" |
Feb. 8 |
"Elastica Models of the Buckling of a Graphene Layer Interacting with a Rigid Substrate" |
Feb. 15 |
"Capturing Knots in Polymers, Proteins, and DNA" |
Feb. 22 |
"An Overview of Structural Applications of Fiber Reinforced Polymer (FRP) Materials" |
Feb. 29 |
"Control of Protein-surface, Protein-protein, and Cell-protein Interactions for Biomedical Applications" |
Mar. 7 |
"Cochlear Implantation 2008" |
Mar. 14 |
"Experimental and Numerical Simulation of Biological Flows" |
Mar. 21 |
No Seminar - Spring Break |
Mar. 28 |
"Mechanical Properties of Nanofiber Composites: Experiment and Modeling" |
Apr. 4 |
"Directed Self-assembly of Block Copolymers: Dots and Lines for Nanofabrication" |
Apr. 11 |
"Learning from 'Coffee Rings': Formation of Ordered Structures by Evaporation Induced Self Assembly" |
Apr. 18 |
"Multi-objective Optimization of Polymer Reactors" |
Apr. 25 |
"Biologically Inspired Organic-Inorganic Nanocomposites" |
May 2 |
"Oil Distribution in Solid iPP/EPDM Thermoplastic Vulcanizates" |
ABSTRACTS
“Impact of Composite Structures”
Dr. Wieslaw Binienda
Professor and Chair of Civil Engineering
The University of Akron
Recent research results aimed at a system of tri-axial, braided carbon fiber composite materials used for blade containment structures in modern jet engines will be discussed. The combination of advanced numerical analysis of material deformation and failure under impact conditions and selective mechanical and impact tests were used to characterize epoxy matrices and composite systems. Large structure ballistic tests were used to validate the models that consequently were used to design composite containment cases. The results of this work have provided significant improvements in the understanding of braided composite systems and impetus for confident application to commercial designs. Two commercial engine companies, General Electric Aircraft Engine (GEAE) Division and Williams International, Inc. (WI), have recently introduced new engine designs that incorporated this technology and a third, Honeywell Corporation (HC), is refining its own design. In all cases, the manufacturers designed and produced viable hardware assisted by numerical models developed from this research and used materials selected in this research. Consequently, they successfully tested their designs under impact conditions. GEAE and WI have demonstrated that their designs can be certified to meet blade-out procedures prescribed by the Federal Aeronautics Administration (FAA).
“Electronic Structure of Conductive Interfaces: Molecular Level Insights ”
Dr. Pavel B. Paramonov
Visiting Assistant Professor
Department of Physics
The University of Akron
Structural and electronic properties of interfaces between solid-state organic/bio-organic materials and electrically conductive surfaces are of considerable interest to a wide variety of fields including energy conversion, plastic electronics, electrochemistry, biocompatibilization, and biosensor technology. A molecular-level understanding of interfacial geometry and energetics provides valuable insights for achieving desired mechanical, thermodynamic and electrical characteristics. We will present theoretical studies of selected interfaces formed by monolayers of organic molecules, weakly as well as covalently bound to conductive surfaces. Geometry, interfacial electronic structure, and electron-vibrational coupling between a molecular film of pentacene physisorbed on the graphite surface will be discussed as an example of a weakly bound interface. A comparison of simulated spectroscopic characteristics with available experimental data will be presented as well. Functionalization of an indium tin oxide (ITO) surface using various phosphonic acids will be addressed as an example of a chemically bound interface. Molecular-level models of ITO surface modification for improved compatibility with organic layers and simultaneous work function tuning will be discussed in the context of applications in organic electronics and polymer-based photovoltaics.
“Elastica Models of the Buckling of a Graphene Layer Interacting with a Rigid Substrate”
Dr. J. Patrick Wilber
Assistant Professor
Department of Theoretical and Applied Mathematics
The University of Akron
We investigate several buckling problems for elastica under non-local body forces. These problems model the interaction by van der Waals forces of graphene - a single-atom-thick sheet of carbon atoms - with a rigid substrate. We present a qualitative analysis of the buckling of graphene subject to edge loading. We also investigate how the spacing between the graphene and the substrate influences buckling. This work is motivated by recently developed techniques for isolating individual graphene layers and by the potential applications of graphene in nanoscale devices and in nanocomposites.
“Capturing Knots in Polymers, Proteins, and DNA”
Dr. Peter Virnau
Institute of Physics
Johannes Gutenberg University
Mainz, Germany
As a topological property of closed strings, knots are primarily a topic of mathematical inquiry, yet they have long captured the imagination of chemists, material scientists and physicists alike. In this talk, I will give an overview on the appearance of knots in polymers, proteins, and DNA. To begin with, I will present the statistics of knots with numerical simulations of a model polyethylene, spanning high temperature (coil) and low temperature (globule) phases. These simulations identify, among others, a strategy to create a novel class of nanoparticles with interesting material properties. Although globular homopolymers display an abundance of knots, only about one in a thousand protein structures are knotted. Can this absence of entanglement be explained in terms of statistical mechanics or is there an evolutionary bias? Do knots in proteins serve a purpose and how do they actually fold? To elaborate on this, I will present an overview of knotted proteins from the current version of the Protein Data Bank. I will also discuss some particularly intriguing examples of this set and explain how knots probably appeared in the cause of evolution.
“An Overview of Structural Applications of Fiber Reinforced Polymer (FRP) Materials”
Dr. Anil Patnaik
Associate Professor
Department of Civil Engineering
The University of Akron
The current state-of-the-art use of fiber reinforced polymer (FRP) materials for civil engineering structural applications such as bridge beams, columns, deck slabs and other members will be presented. FRP has been gaining popularity among engineers for strengthening of existing structural members and for new structures. This presentation will include a brief introduction to materials used in civil engineering structures, strengthening techniques, design methods, and current and future research trends. Areas of interdisciplinary research needs will also be identified for potential collaborations.
“Control of Protein-surface, Protein-protein, and Cell-protein Interactions for Biomedical Applications”
Dr. Lingyun Liu
Assistant Professor
Department of Chemical and Biomolecular Engineering
The University of Akron
Engineering surface properties at the molecular level to control protein adsorption, orientation and distribution on surfaces and to modulate cell behavior will provide insights for the design of new biomaterials and tissue scaffolds with superior biocompatibility and for the development of surface-based sensing strategies with high sensitivity and specificity. An improved method to prepare carboxylic acid (COOH) and amine (NH2) terminated self-assembled monolayers (SAMs) of alkanethiolates on gold will first be discussed to control surface chemistry at the molecular level. Approaches to control protein orientation on surfaces will then be presented, which are essential to the improvement of biosensor sensitivity and the promotion of normal wound healing of implanted biomaterials. Protein distribution, or gradient, plays an important role in cell migration and angiogenesis. The effect of the surface-density gradients of extracellular matrix (ECM) proteins and growth factors on the endothelial cell migration will be presented. I will also briefly discuss the newly developed zwitterionic non-fouling materials for their resistance to protein adsorption and cell adhesion in vitro and in vivo.
“Cochlear Implantation 2008”
Dr. Anil Kumar Lalwani
Mendik Foundation Professor and Chair of Otalaryngology
New York University School of Medicine
Cochlear implants are electronic devices used to provide sound sensations to persons who are severely hard-of-hearing or profoundly deaf. The purpose of the implant is to provide the recipients (additional) auditory information preferably including sound discrimination fine enough to discern speech. Current devices typically consist of an external portion along with a second portion surgically placed under the skin. Current practice also involves post-implantation rehabilitative therapy to improve the success rate. Dr. Lalwani will present the state of the art in this implantation technique with information on the current devices used, their placement and operational principles and typical outcomes.
“Experimental and Numerical Simulation of Biological Flows”
Dr. Francis Loth
F. Theodore Harrington Endowed Associate Professor
Department of Mechanical Engineering
The University of Akron
This seminar will describe the results of experimental and computational fluid dynamic simulations in three different biological flow configurations: the carotid bifurcation, an arteriovenous graft, and cerebrospinal fluid in the spinal canal. The ability to model biological flows has become an important component of disease research particularly with regard to mechanotransduction in the human body. Magnetic resonance (MR) imaging has become a powerful engineering tool to obtain three-dimensional geometry and velocity in vivo with surprisingly good spatial and temporal resolution considering it is a non-invasive procedure. These images provide the necessary boundary conditions in order to compute the biomechanical forces within vessels. Computational biofluids may one day be conducted on patients as a normal part of diagnostic procedures.
Hemodialysis grafts have blood flow rates greater than that typically found in normal vessels of the same size. Thus, the mean Reynolds numbers are higher than normal (1000-3000) and transition to turbulent flow is present. We have conducted experimental velocity measurements using laser Doppler anemometry within a graft model that represents this graft geometry. Numerical simulations with the same geometry and flow conditions were conducted by employing the spectral element technique. Coherent structures (vortices) from numerical simulations at Reynolds numbers well below 2100 were identified. Good agreement between the experimental and computational results was obtained. The magnitude of these velocity and pressure fluctuations appears to be an important factor in the early failure of these grafts.
In addition, the fluid dynamics within the carotid bifurcation and the spinal canal will also be described along with the potential importance of such simulations in surgical planning and diagnosis. Many medical researchers believe that the non-invasive quantification of biomechanical forces will be increasingly important to the understanding and diagnosis of disease
“Mechanical Properties of Nanofiber Composites: Experiment and Modeling”
Dr. Zhenhai Xia
Assistant Professor of Mechanical Engineering
The University of Akron
Nanofibers made from various materials such as polymers, carbon and semiconductors have been used for a wide range of applications such as tissue engineering, filter media, reinforcement in nanocomposites and micro/nano-electro-mechanical systems. In most of these applications, the nanofibers, whether in the formation of mats or composites, are subjected to stresses and strains from the surrounding media during their service lifetime. This talk is focused on the mechanical aspect of nanofibers and their composites (mats). I will first present our recent efforts on experiment and modeling of carbon nanotubes with interwall sp3 bonds, and then the work on CNT reinforced ceramic composites. Nanoindentation was used to measure the buckling properties of CNTs and fracture toughness of the composites. Finally, I will discuss our preliminary results on modeling of electrospun polymer nanofibers and their mats. The models we used are multiscale in nature, including a molecular dynamics model for simulating the deformation and damage of single nanofiber at atomic scale and a coarse grained method for predicting the fiber-fiber interactions and failure in larger scale samples.
“Directed Self-Assembly of Block Copolymers: Dots and Lines for Nanofabrication”
Dr. Ho-Cheol Kim
Researcher
IBM Almaden Research Center, San Jose, CA
It is of great interest to utilize the periodic nanostructures of block copolymers in thin films for advanced patterning schemes in the semiconductor industry. Previous studies show that patterns of sub-optical lithographic feature sizes are easily attainable with block copolymers and can be used for fabricating semiconductor devices. In this talk, a recently developed block copolymer containing hybrid material and controlled assembly in thin films will be presented. By combining with semiconductor processing technology, the hybrid system offers unique ways to fabricate nanostructures without costly, complex, and intensive processing. Examples of directed self-assembly of the microdomains for specific integration schemes of electronic devices will be discussed along with recent progress in formation of nanostructured functional materials for photovoltaic applications.
“Learning from 'Coffee Rings': Formation of Ordered Structures by Evaporation Induced Self Assembly”
Dr. Zhiqun Lin
Assistant Professor of Materials Science & Engineering
Iowa State University
Self-assembly of micro- and nano-scale materials to form ordered structures promises new opportunities for developing miniaturized electronic, optoelectronic, and magnetic devices. In this regard, several elegant methods based upon self-assembly have emerged, for example, self-directed self-assembly and electrostatic self-assembly. Dynamic self-assembly of nonvolatile solutes via irreversible solvent evaporation has been recognized as an extremely simple route to intriguing structures. However, these dissipative structures are often randomly organized without controlled regularity. In this presentation, I will show a simple, one-step technique based on very simple "coffee ring" phenomena to produce well-ordered structures (e.g., concentric rings, fingers, spokes, etc.) consisting of polymers or nanocrystals (NCs) with unprecedented regularity by allowing a drop of polymer or NC solution to evaporate in a sphere-on-flat geometry. This technique, which dispenses with the need for lithography and external fields, is fast, cost-effective and robust. As such, it represents a powerful strategy for creating highly structured, multifunctional materials and devices.
“Biologically Inspired Organic-Inorganic Nanocomposites”
Dr. Ilhan A. Aksay
Professor of Chemical Engineering
Princeton University
Biologically produced materials are multifunctional and have properties, e.g., sensing and actuation, self-replication, self-healing, that we are yet to introduce into man-made materials. The objective of this presentation will be to provide an understanding of the biological processes for controlling materials properties through nano- and microstructural design and processing with the goal of attaining multifunctionality. "Self-assembly" and "pixelation" are the prevailing mechanisms used in the construction of biological structures. Self-assembly is now recognized as an economically favorable technique for rapid fabrication of nanostructures similar to those observed in biological systems. However, the current methods suffer from drawbacks that limit their application: (i) Self-assembled structures have uncontrolled multiple domains at micrometer and larger length scales due to the statistical nature of domain nucleation and growth. (ii) The location of individual structures cannot be controlled, making integration into macroscopic structures difficult. (iii) The small size and high density of self-assembled units require new methods of addressing, differentiating, and interconnecting. To address these drawbacks, I will demonstrate examples of the integration of self-assembled nm- to µm-scale building blocks into spatially defined ("pixelated") macroscopic structures. As an alternative approach, I will also demonstrate how some of the structural design principles utilized in biological nanocomposites can be used with nanofillers such as molecular sheets of graphene to produce polymer matrix composites that display multifunctional properties.
“Oil Distribution in Solid iPP/EPDM Thermoplastic Vulcanizates”
Dr. Tonson Abraham
Research Principal
ExxonMobil Chemical Company
Scanning Probe Microscopy (SPM) was used to determine the volume fraction of oil-swollen particulate rubber and oil-swollen plastic in thermoplastic vulcanizates (TPVs) produced from iPP and EPDM rubber. In this connection, a principle of stereology, which equates measured area fractions of the TPV phases to volume fractions, was utilized. This principle is applicable to homogeneous and isotropic samples, provided that a sufficiently large number of random sections are analyzed to determine phase areas. The hydrosilylation cured TPVs contained no filler or inorganic components (other than about 1 ppm of platinum catalyst, based on dry rubber) that would decrease the accuracy of the SPM analysis. The accuracy of the SPM method used for TPV phase volume determination was established by analysis of an oil-free TPV of known composition. The densities of the individual TPV components (rubber, oil, crystalline and amorphous plastic phase), which were assumed to be additive in the composite, were used to calculate the oil distribution between the TPV rubber and plastic phase, since the volumes of the individual components (the extent of plastic crystallinity was measured by differential scanning calorimetry) were known. Thus, the amount of oil in the oil swollen TPV rubber and plastic phase could be quantified. This information, coupled with the Tg of the oil-swollen amorphous plastic phase, indicated that a substantial amount of oil was present as a separate oil phase that is surrounded by the oil-swollen amorphous plastic phase. Indeed, high resolution SPM revealed the presence of submicron pools of oil in the TPV plastic phase.
To date, it has been assumed that the oil in a TPV partitions between the rubber and amorphous plastic phase, with the plastic crystallites being oil free. This work is the first demonstration of the presence of a separate oil phase in TPVs, and the first accurate determination of the oil content in the oil-swollen rubber, miscible oil in the oil-swollen amorphous plastic, and the free oil in TPVs.
© 2008 by The University of Akron - Contact Us
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Department of Polymer Engineering
Polymer Engineering
Academic Center
The University of Akron
Akron, OH 44325-0301
Phone: 330-972-5281
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