Home > Seminars > Fall 2007 Seminar Series
FALL 2007 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 |
Aug. 31 |
"Structures of Cellulose and Chitin" |
Sept. 7 |
"Recent Developments on Twin Screw Extrusion" |
Sept. 14 |
"Polyolefin Functionalizations Via Reactive Extrusion and Modeling" |
Sept. 21 |
"Anionic Synthesis and Applications of Functionalized Polymers" |
Sept. 28 |
No Seminar |
Oct. 5 |
"Birefringence, Anisotropic Shrinkage and Luminance in Light Guide Plates: Modeling and Experiment" |
Oct. 12 |
"The Evolution and Applications of Twin Screw Extruders" |
Oct. 19 |
"Rubber Nanocomposites: Some Recent Examples" |
Oct. 26 |
"Nanoscience and Nanotechnology in Coffee Rings" |
Nov. 2 |
"Mechanism and Significance of Slip During Flow in Metered Intermeshing Co-Rotating
Twin Screw Extruder" |
Nov. 8 & 9 |
Bayer Lectureship - "Biointerface Engineering for Healing and Reconstruction" and "Foundation Ideas for Tissue Engineering: Application to Heart Muscle and Esophagus" |
Nov. 16 |
"Internal Intensive Mixers and Mixing Parameters" |
Nov. 23 |
No Seminar |
Nov. 30 |
"Mechanical and Molecular Deformations of Polymer Nanofibers" |
Dec. 7 |
Cancelled - "Oil Distribution in iPP/EPDM Thermoplastic Vulcanizates" |
ABSTRACTS
“Structures of Cellulose and Chitin”
Dr. John Blackwell
Department of Macromolecular Science
Case Western Reserve University
This lecture will review work done at Case Western Reserve University on the structures of cellulose and chitin, putting it into context within the long history of the X-ray analysis of these materials that date from 1920. The implications of these studies for our understanding of industrial applications and biosynthesis of these abundant natural resources will be discussed. Recent work on chitin nanocomposites will also be described.
“Recent Developments on Twin Screw Extrusion”
Dr. Martin Mack
Vice President of Research & Development
Berstorff Corporation
This lecture will cover the following topics:
- Introduction to the KraussMaffei-Berstorff organization
- New hardware options:
- ZE twin screw building blocks of the UTX series
- New screw elements for special process requirements
- UP-elements for elongational mixing
- CH-element for more efficient pressurization
- MP-elements for shear sensitive fillers and PVC compounds
- IKT- combing elements for entangling of long fiber networks
- Integrating in tandem with single screw extruders and sheet extrusion:
- sheet lines for TPO multi layer industrial roofing membranes
- foam tandem lines with melt cooling single screw extruders
- continuous feeding of rubber bales in TPV tandem lines
- the Injection Molding Compounder for long fiber reinforced products
“Polyolefin Functionalizations Via Reactive Extrusion and Modeling”
Dr. Eung Kyu Kim
Research Specialist
Dow Chemical Company
In recent years, there has been increased interest in Reactive Extrusion (REX) processes within The Dow Chemical Company because the chemical and plastic industries are facing the consistent challenges to launch new products, differentiated products and economically advantaged products. The REX processes can potentially allow cost-effective conversion of low cost commodity polymers, such as polyolefins, to higher priced specialty polymers. This presentation will cover the overview of the REX process and the methodology to design the REX process for a given formulation and reaction system through the examples of currently practiced polyolefin functionalizations via REX processes in The Dow Chemical Company. To date much of the work in the REX process has been of the "try and see" approach, and more fundamental kinetic modeling studies are not abundant. These kinetic modeling studies may be more difficult, but have great potential to allow for conceptual leaps than do the more empirical approaches. This presentation will also review the REX kinetic modeling efforts in The Dow Chemical Company.
“Recent Advances in the Anionic Syntheses of Functionalized, Block and Star-branched Polymers”
Dr. Roderic P. Quirk
Department of Polymer Science
The University of Akron
Living alkyllithium-initiated polymerizations in hydrocarbon media provide excellent methods for the synthesis of well-defined polymers such as chain-end functionalized, star-branched and block polymers. Commercial production of such anionically prepared polymers corresponds to more than 2,700,000 metric tons annually. An overview of these polymerization methods will be provided. Recent advances in the anionic synthesis of functionalized polymers, e.g. in-chain, chain-end and functionalized monomers, will be described including applications. The anionic syntheses of well-defined block copolymers and their applications for preparation of ordered, nanoscopically-dispersed metal ions and metals will be discussed. New methods for the synthesis of well-defined star-branched polymers will be described.
“Birefringence, Anisotropic Shrinkage and Luminance in Light Guide Plates: Modeling and Experiment”
Mr. Tsui Hsun Lin
Doctoral Student in Polymer Engineering
The University of Akron
The frozen-in flow birefringence and anisotropic shrinkage of injection molded light-guide plates (LGPs) was simulated using a combination of a control volume/finite element method/finite difference method, nonlinear viscoelastic constitutive equation and orientation functions. In addition, the frozen-in thermal birefringence in LGPs was simulated using the linear viscoelastic and photoviscoelastic theories with inclusion of the volume relaxation phenomena. The relaxation modulus function and the strain- and stress-optical coefficient functions were measured and utilized in this simulation. In calculating the thermal birefringence constrained quenching of LGP in the mold until packing pressure removal followed by free quenching was utilized. Then the total frozen-in birefringence in LGPs was calculated as a sum of both the flow and thermal birefringences.
LGP moldings were prepared from two optical grade polycarbonates (PC) and various components of residual birefringence along with shrinkages in the length, width and thickness directions were measured. The predicted results for various birefringence components have been compared with experimental data obtained at different processing conditions. Also the luminance and degree of transcription of microgrooves of LGP moldings were measured indicating their strong dependence on processing conditions. Imperfections in filling of the microgrooves are influenced by local pressure and temperature histories.
“The Evolution and Applications of Twin Screw Extruders”
Mr. Charles Martin
General Manager
American Leistritz Extruder Corporation
High Speed Energy Input (HSEI) twin screw extruders are the manufacturing methodology of choice in the plastics industry for compounding, devolatilization, and reactive extrusion. The final product can be pellets for subsequent forming processes, or the direct extrusion of a fiber/film/sheet or profile. Recent design enhancements to the HSEI twin screw extruder offer the benefit of higher torque, better cooling and more free volume.
HSEI twin screw extruder barrels are modular, electrically heated, liquid cooled and serve as individual temperature control zones. Segmented screw elements that convey materials and impart shear are assembled on high torque shafts and staged based upon the process demands. Electrical energy is converted to mechanical energy through the drive train (motor-gearbox) and applied to the material as shear through the rotating screws.
Free volume is a common term in extrusion and is directly related to the OD/ID ratio, which is defined by dividing the outer diameter (OD) by the inner diameter (ID) of each screw. The industry standard OD/ID ratio is 1.55/1, however a new HSEI twin screw extruder series facilitates a 1.66/1 OD/ID ratio with the same screws centerline and higher torque as previous designs.
Torque is directly related to the diameter and design of the screw shaft. The larger the diameter of the screw shaft, the higher the torque capability. While deeper screw channels offer more free volume, it is at the expense of the torque capability of the shafts since a smaller diameter shaft is necessary. Based on the use of a symmetrical, hammered splined shaft a 1.55/1 OD/ID ratio has generally been deemed to offer the best balance of torque and volume. A new asymmetrical splined shaft design attains increased torque with a smaller diameter shaft, which allows a 1.66/1 OD/ID ratio and higher free volume without sacrificing torque. Heat transfer capacities have also been improved by increasing the coolant flow to each barrel section.
Experimental data has been generated to compare HSEI twin screw extruders with 1.55/1 and 1.66/1 OD/ID ratios. A 40 L/D process length was utilized for this evaluation, as well as similar screw designs and operating conditions. HDPE, LDPE, and PLA were used as test materials to evaluate capacity differences between the two different process geometries.
The test results indicate that the combination of high torque and deeper screw flight channels enable higher throughput rates and lower melt temperatures. This combination of attributes makes it possible to process a wider variety of materials for traditional plastics, as well as for emerging applications in the pharmaceutical industry.
“Rubber Nanocomposites: Some Recent Examples”
Dr. Anil K. Bhowmick
Rubber Technology Centre
Indian Institute of Technology, Kharagpur
Nanocomposite is a field of extensive research in recent years. This is a class of organic-inorganic hybrid materials, where the inorganic component is uniformly distributed in nanometer scale (10-9 m) within the polymer matrix. The reinforcing inorganic components are mostly nanoclay, silica, graphite, carbon nanotubes (CNT) etc. Naturally occurring or synthetic clays are first modified into polymer compatible nanoclays and then dispersed in the matrix by three different methods, namely, solution intercalation, in-situ polymerization and melt intercalation. For polymer-silica nanocomposites, the usual preparation method is a sol-gel technique, where the in-situ silica generation is conducted by sequential hydrolysis and condensation of an inorganic precursor of silica like alkoxysilyl compounds. Smectite group of clays has also been synthesized in our laboratory. The present lecture will highlight a few current studies on various rubber- and thermoplastic elastomer based nanocomposites. A few examples will also be given for in-situ nanocomposites. The resultant nanocomposites exhibit superior mechanical, dynamic mechanical, thermal and barrier properties over the composites made from conventional clays and silica even at lower filler loading. The results can be explained with the help of morphology, interaction between the components, adsorption phenomena, surface and cleavage energy balance and thermodynamics. On the basis of these, a new mechanism for polymer intercalation into clay galleries has been proposed.
“Nanoscience and Nanotechnology in Coffee Rings”
Dr. Zhiqun Lin
Department 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 to produce well-ordered structures (e.g., concentric "coffee" rings, fingers, spokes, etc.) consisting of polymers or nanoparticles with unprecedented regularity by allowing a drop of polymer or nanoparticle 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. More information can be found on my research group website: http://zqlin.public.iastate.edu.
“Mechanism and Significance of Slip During Flow in Metered Intermeshing Co-Rotating Twin Screw Extruder”
Mr. Kyun Ha Ban
Doctoral Student in Polymer Engineering
The University of Akron
Twin screw extrusion is one of the most important continuous polymer processing operations. It is used for compounding, blending, reactive extrusion and devolatilization. Twin screw extruders include a range of different processing machines. Twin screw extruders are divided into three types according to the arrangement of their screws: non-intermeshing, tangential, and intermeshing twin screw machines. They are also classified according to screw rotation directions; co-rotating twin screw extruders and counter rotating twin screw extruders. There are three predominant designs that have evolved i) intermeshing co-rotating (self-wiping) ii) intermeshing counter rotating and iii) non-intermeshing counter rotating.
Modern twin screw extruders have modular construction and possess screw and mixing elements, barrel segments, feed ports and vents. These individual screw elements, mixing elements and barrel segments may be configured in various ways to perform the desired process requirements. During the extrusion of some polymeric materials and their compounds, we find the occurrence of slip on the surfaces of screw, barrel and dies. There is a long history of investigations of slip phenomena [1-5]. Slip during the flow of neat polymer melts and compounds seems to be the result of unstable flow [6-8], low pressures [9] and special surface coatings [9,10]. The special surface coatings are often amphoteric molecules deposited from compounds. This has recently been investigated by Ahn and White [11-13]. It has been recognized in recent years that slippage may occur in flow in twin screw extruders. Generally these papers are concerned with flow modeling of local fully filled regions in these machines and presume an arbitrary hypothetical constitutive equation for the slip velocity. Issues of how slippage should influence the performance of twin screw extruder are not addressed.
In this presentation, I will discuss (i) experimental conditions for the occurrence of slippage in polyolefins including high density polyethylene, polypropylene, polybutene, Poly(4-methylpentene-1) and a cyclopolyolefin and compounds and show analytical equations describing the slippage (ii) experimentally investigate the behavior of polymers exhibiting slippage in a modular self-wiping twin screw extruder involving fully filled region (iii) examine how slippage influences machine performance.
References:
1. J. J. Benbow and P. Lamb, Am. Chem. Soc., Div. Polymer Chem., Preprints, 3, 33 (1962).
2. M. Mooney, Journal of Rheology, 2, 210 (1931).
3. M. Mooney, Proc Int. Rubber Conf., Washington DC, 358 (1959).
4. M. Mooney and S. A. Black, Journal of Colloid Science, 7, 204 (1952).
5. R. K. Schofield and G. W. S. Blair, Journal of Physical Chemistry, 34, 248 (1930).
6. J. J. Benbow and P. Lamb, SPE Trans., 3, 7 (1963).
7. J. P. Tordella, Journal of Applied Polymer Science, 7, 215 (1963).
8. A. Wunsche, German Patent 131,392 (1901).
9. D. S. Kalika and M. M. Denn, Journal of Rheology 31, 815 (1985).
10. E. Lee and J. L. White, Polymer Engineering and Science, 39, 327 (1999).
11. S. Ahn and J. L. White, Journal of Applied Polymer Science, 90, 1555 (2003).
12. S. Ahn and J. L. White, International Polymer Processing, 18, 243 (2003).
13. S. Ahn and J. L. White, Journal of Applied Polymer Science, 91, 651 (2004).
“Biointerface Engineering for Healing and Reconstruction”
Dr. Buddy D. Ratner
Director, University of Washington Engineered Biomaterials (UWEB)
Darland Endowed Chair in Technology Commercialization
Professor of Bioengineering and Chemical Engineering
University of Washington, Seattle
The needs for repair and replacement of damaged and diseased tissues and organs are pressing and imperative. Synthetic biomaterials and medical devices have attempted to address these needs. The use of synthetic materials for medical devices and implants has a modern history extending back some 60 years. The materials used have largely been derived from commercial/commodity materials modified to demonstrate acceptable toxicology. Such materials (examples: silicone elastomers, fluoropolymers, polyurethanes and Dacron) have advantages of desirable mechanical properties and biodurability, though generally their biological performance is sub-optimal. Particular problems are chronic (low level) inflammation, fibrosis, thrombosis, calcification and infection. The response of the body to such materials implanted in most tissue spaces is a fibrotic, avascular capsule walling the material from the body. Furthermore, this response is characteristic of chronic inflammatory reaction with activated macrophages, even years after implantation.
More recently, biomaterials design has asked questions about normal biological healing and how surfaces and materials might mimic or attenuate the normal biological processes. Proteins and biomolecules on surfaces and in scaffolds have been explored in biomaterials, tissue engineering and regenerative medicine to induce healing and reconstruction. However, most often, these proteins have been non-specifically immobilized or incorporated into materials with no concern for their orientation or conformational stability. Here we discuss the positive outcomes that come from using engineered surfaces to specifically control protein orientation and conformation with the goal to deliver desired signals to cells. In addition, the use of polymer architecture (precision porosity) to control cells will also be discussed and in vivo healing data presented. These methods offer the potential for much improved healing and integration of prostheses and also directly contribute to tissue engineering.
“Foundation Ideas for Tissue Engineering: Application to Heart Muscle and Esophagus ”
Dr. Buddy D. Ratner
Director, University of Washington Engineered Biomaterials (UWEB)
Darland Endowed Chair in Technology Commercialization
Professor of Bioengineering and Chemical Engineering
University of Washington, Seattle
This talk will present results from two University of Washington tissue engineering projects focused on heart muscle and esophagus. There are foundation technologies and concepts that underlie the engineering of these two very different tissues (and, in fact, all tissues). These foundations are: angiogenesis, innervation, surgical integration, appropriate biomechanics, inflammation/healing, cell sources and market realities. In the context of heart muscle and esophagus, these necessities will be discussed. In particular, the use of instructive scaffolds and biological surface signals to achieve many of these goals will be presented. Two types of scaffolds will be demonstrated. One is made by sphere-templating and has pores that are uniform in size. The other is made by decellularization of esophagus. Other technologies used in conjunction with the scaffolds to achieve the objectives will be presented. Finally, a discussion of the commercialization aspects of tissue engineering will be made, for unless an appropriate business model is arrived at, there will be little or no clinical application of tissue engineering.
“Internal Intensive Mixers and Mixing Parameters ”
Mr. Richard J. Jorkasky, II
Lab Manager
Kobelco Stewart Bolling, Inc.
This presentation briefly covers the history of mixing, internal mixers, and spends a great deal of time looking into the influence various parameters have on the mixing of rubber. Background information and comparative data will be presented to highlight the effects that different rotor designs and other mixing parameters (such as rotor speed, rotor orientation and material addition schemes, to name a few) have on the mix cycle time, Mooney Viscosity and other properties of various rubber systems.
Biography
Mr. Jorkasky graduated with a B.S. in Chemistry from Carnegie-Mellon University. He spent the first 23 years of his career with Standard Oil of Ohio (Sohio)/British Petroleum in Cleveland, Ohio, doing everything from bench top research to pilot plant scale up to product manufacturing to customer service to material processing of numerous polymeric systems. When BP moved to Chicago in 1999, Mr. Jorkasky left to become the Pilot Plant/Laboratory Manager of Kobelco Stewart Bolling, Inc. in Hudson, Ohio, doing mostly rubber and some plastics mixing with internal mixers, production mixing for customers, and consulting on mixing and mixing problems. He has 12 patents and has authored/co-authored 12 publications on the processing and mixing of rubber and plastics.
“Mechanical and Molecular Deformations of Electrospun Polymer Nanofibers ”
Dr. Shing-Chung Wong
Department of Mechanical Engineering
The University of Akron
This study examines the tensile toughness and mechanical deformation of electrospun biodegradable poly(ε--caprolactone) (PCL) with varying hydroxyapatite (HAP) content (0 - 30 wt%). Toughness of HAP-filled PCL was examined for the electrospun fibers using the essential work of fracture (EWF) concept. The electrospun fibers exhibited a range of diameters and a combination of HAP particle sizes ranging from (50-100 nm) under the SEM. The tensile stress-strain behavior and fracture toughness of electrospun nanofibers were assessed using a nanoforce tensile tester. The electrospun system showed a substantial increase in plane-stress essential work of fracture in comparison to bulk specimens processed from pellets. Toughness decreased as HAP loading increased. Compression molded electrospun nanofibers were compared with unmolded samples. It was found that the tensile strength and stiffness of molded and spun fibers are remarkably higher than those from molded specimens of pellets. The molecular orientation and change in crystallinity were evaluated using X-ray diffraction techniques.
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