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Expert in Polymer Process Monitoring, Dielectric, Fluorescence, Optical, Ultrasonics, Rheology
Available for your Consulting and Expert Witness Needs
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Summary of Expertise:
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Listed with other top experts in: |
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He has gained considerable knowledge about amorphous polymers through mechanical and dielectric measurements and through extrusion and injection molding processing. Fluorescence monitoring experiments during the injection molding of amorphous polystyrene showed how the onset of the glass transition is affected by the application of pressure. Dielectric relaxation time measurements on amorphous and semi-crystalline polymers describe the dynamics of the amorphous phase. His studies with nylon clay nanocomposites demonstrate how the filler material impacts molecular dynamics in the amorphous phase.
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Over the course of 45 years of polymer science research, he has had several occasions to run capillary rheometer experiments. In one study, he instrumented a capillary rheometer with an optical fiber sensor and measured the effect of shear heating on the capillary extrudate using a temperature sensitive fluorescent dye. In some cases at high shear rates, shear heating can be significant. In a recent paper, presented at SPE ANTEC in 2006, he presented the design of a new capillary (slit) micro-rheometer that requires mg size samples to obtain viscosty - shear rate relationships. The dielectric slit die that he developed is also a slit die rheometer with which viscosity of an extruded resin can be measured from the pressure drop and the resin flow rate.
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In his models of injection molding of crystalline and amorphous polymers, he carried out extensive computational programs to describe the heat conduction, resin crystallization, the onset of the glass transition in amorphous polymers, and product shrinkage during the cool down phase. The computations involved the incorporation of a number of physical principles: thermal conductivity through resin and steel mold, abiabatic heating, heat of crystallization, spherulitic crystal growth, impact of temperature and pressure on resin equation of state, creation of interferometer geometry during shrinkage, the temperature dependence of fluorescence spectra, and light scattering from micro crystals.
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His experimental research required the continuing development of new tools to analyze data and to reduce data to meaningful terms. To do this he has used software programs such as LabView, Excel, and Chemometrics as well as developing his own software for computations and simulations.
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The study of dielectric materials and their properties as a function of temperature and frequency, has been an ongoing theme in Expert's work. He has carried out research on dielectric properties of polymers in solution and in the solid and molten states. Some of his work on dielectrics dates back 45 years. The most recent study of polymer dielectric properties was done on a family of nylons that includes real-time measurements during the compounding and extrusion of nylon/clay nanocomposites. He used observations of Maxwell-Wagner relaxations to show the relationship between relaxation time and the amount of clay exfoliation. He use off-line measurements to demonstrate the efects due to clay particles on dielectric relaxation.
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As leader of the NIST dielectrics team for polymer processing applications, he designed and developed the dielectric slit die sensor that was used to monitor polymer/clay compounding. This sensor, based on interdigitating electrode technology, was designed to operate to 300 oC and to 3000 psi, and contained ports for pressure, temperature, optical and ultrasonic sensors. It is a multi-functional device from which a stream of data can be obtained simultaneously from the different sensors during real-time monitoring of extrusion. The dielectric slit die allows for high throughput, combinatorial measurements that provide a broad view of the extruded compound. He also developed the NIST protocol for analyzing dielectric and optical transmission data.
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Under Expert's leadership, the NIST dielectrics team employed a full frequency and temperature range of dielectric measurements in order to observe relaxation times that reflect the molecular dynamics. Changes in relaxation times with the addition of clay filler particles in the matrix resin showed how the molecular dynamics are affected by the presence of clay particles and exfoliated clay nano-flakes. For the nylons compounded with clay, the impact of clay filler on molecular dynamics was observed over a broad range.
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The Expert-McBrearty dielectric slit die is an instrumented extrusion die that is used to measure dielectric, optical, ultrasonics and rheological properties of an extruded resin. The die is in the form of a slit that is the platform for several sensors and is in itself a slit die rheometer.
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Dr. bur has extensive experience using fluorescence measurements to monitor polymer processing and to characterize molecular orientation in polymer films. He has employed fluorescent probe molecules, called band definition dyes, to monitor temperature during extrusion and during capillary rheometer testing. The properties of band definition dyes were described in a paper by Expert in Applied Spectroscopy, 2002. Molecular orientation is obtained from fluorescence anisotropy measurements, which he has applied to several manufacturing processes, extrusion through a slit die and biaxial stretching of polypropylene films. These experiments have been described in papers published in Review of Scientific Instruments, Macromolecules, and two papers in Polymer Engineering and Science.
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Expert has developed three fluorescence measuring sensors, two optical sensors for measuring fluorescence from temperature sensitive dyes and the fluorescence anisotropy sensor. These sensors were designed to monitor real-time processing at elevated temperatures. Two sensors are designed for monitoring temperature: one for injection molding is an optical fiber that is inserted into the ejector pin channel of a mold and the other is an optical fiber that is encased in a sensor bolt and inserted into the standard Dynisco port on an extrusion machine. The fluorescence anisotropy sensor is designed to measure vertically and horizontally polarized light simultaneously and is described in papers in Review of Scientific Instruments and Poltymer Engineering and Science.
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Interferometry was the tool that Dr. bur employed to measure shrinkage in injected molded plastic parts during the cooling phase of the process. During shrinking, a part will separate from the mold and optical fiber sensor, setting up the geometry of a Fabry-Perot interferometer. By counting light fringes as a function of time, shrinkage rates can be measured.
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Expert and his colleagues at NIST studied a family of nylons (6, 11, 12) compounding them with montmorillonite clay. The nylons are known to provide a resin matrix that favors exfoliation of organo-modified clays at processing temperatures. Using the dielectric slit die to monitor both dielectric properties and optical transmission during extrusion, relationships between dielectric relaxation time, optical transmission and the amount of exfoliation were expressed in an extent-of-exfoliation model.
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Expert designed a "dynisco" type optical sensor that is contained in a a 1/2 inch dynisco style bolt. The bolt has a hollow shaft along its axis and a sapphire window at its end. An optical fiber capped by a lens is inserted into the hollow bolt shaft. The fiber carries incident light to the sample and also picks up the detected transmitted light or fluorescence from the sample. By moving the lensed optical fiber along the shaft, the incident light can be focused to different spots in the sample. This sensor has been used to detect fluorescence from temperature sensitive dyes and to detect changes in transmitted light through the sample.
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Expert and his colleagues at NIST carried out a substantial amount of work on the development of PVDF piezoelectric transducers. They not only studied depolarization effects at the molecular level, but also designed and constructed transducers that were used in military applications.
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Using optical and pressure sensors to monitor injection molding, Expert studied the dynamics of plastics injection molding using polystyrene, polyethylene, and polypropylene. The optical sensor was inserted through the ejector pin channel and faced up to one side of the sample. Fluorescence probe molecules mixed with the sample provided information about the temperature and crystallization of the resin. Shrinkage was also detected when the molded product pulled away from the mold wall.
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Modeling of plastics injection molding, carried out by Expert, was based on experimental observations of fluorescence and optical transmission during the molding cycle. To model the experiments, physical concepts such as thermal conductivity, crystallization, adiabatic heating, equation of state, and glass formation were employed.
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Compounding of clay and polymer nanocomposites has been at the heart of a research program carried out by Expert and his research team at NIST. Compounding clay with a family of nylons was monitored using dielectric, optical and fluorescence measurements. The observations formed the basis for a model of the extent of exfoliation.
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Expert has carried out experiments on polymer crystallization using fluorescence spectroscopy to track crystallization during injection molding. Effects of heat of crystallization and pressure on crystalline growth were described in model calculations that supported the fluorescence observations.
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Polymer extrusion, both single screw and twin screw compounding, has been the focus of Expert's process monitoring research during the past 20 years. He has worked with industry partners to monitor temperature in resin flow streams, to measure the quality of compounding, and to monitor dielectric and rheological properties of resins during extrusion.
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The broad field of polymer physics is Expert's main area of expertise. He has spent his 45 year career studying and carrying out resaerch in polymer physics. These studies have included dielectric, mechanical, solution, thermodynamic, piezoelectric, molecular confirmmation, crystallization and glass forming properties of polymers.
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Expert initiated the NIST process monitoring program and was its leader for the last fifteen years of his career there. He also founded and chaired the Process Monitoring and Control Group in the Society of Plastics Engineers.
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Expert not only carried out rheological measurements using conventional capillary and cone and plate rheomoters, but also he designed a new slit die micro-rheometer that uses less than 20 mg of material to obtain viscosity vs shear rate data.
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Show Secondary and Basic Areas of Expertise | Localities:
Expert may consult nationally and internationally, and is also local to the following cities: Baltimore, Maryland;
Frederick, Maryland;
Gaithersburg, Maryland;
Bowie, Maryland;
Richmond, Virginia;
Alexandria, Virginia;
Wilmington, Delaware;
and Lancaster, Pennsylvania.
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Degree |
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Subject |
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Institution |
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1957
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BS
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Physics
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St. Joseph's University, Philadelphia
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1962
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PhD
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Physics
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Pennsylvania State University
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| Years |
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Employer |
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Department |
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Title |
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Responsibilities |
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2005 to
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(Undisclosed)
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President
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He directs instrument design, manufacturing, negotiations with suppliers and clients, and establishes price structure.
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2005 to 2008
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National Institute of Standards and Technology
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Polymers Division
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Visiting Scientist
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He collaborates with NIST scientists on the design, construction and application of a micro-rheometer to measure rheological properties of polymers.
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1963 to 2005
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National Institute of Standards and Technology
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Polymers Division
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Distinguished Physicist
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During a distinguished career that spanned 42 years, he initiated and directed many research projects. He was the founder and leader of the NIST polymer processing program, the NIST Measurements for Polymer Processing Consortium, the Polymer Nanocomposite Process Monitoring Program, and the real-time Dielectric Properties Monitoring Project.
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1962 to 1963
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Johns Hopkins University
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Dept. of Mechanics
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Post-doctoral fellow
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He carried out research on the dielectric and mechanical properties of polymers.
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1958 to 1961
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Penn State University
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Physics Dept.
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Teaching Assistant
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He taught undergraduate physics courses and laboratory classes.
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Associations/Societies
Fellow, Society of Plastics Engineers
Anerican Chemical Society
American Physical Society
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Professional Appointments
He is an associate editor of Polymer Engineering and Science
He is on the peer review staff for Review of Scientific Instruments, Journal of Applied Physics, Applied Physics Letters, Journal of Applied Polymer Science, and International Journal of Polymer Processing
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Awards/Recognition
He has received many awards for his contributions to polymer science and engineering including
U. S. Department of Commerce Bronze Medal, 1992, Citation: "For creative development of fluorescence methods for monitoring polymer processing and significant contributions to technology transfer"
U. S. Dept. of Commerce William P. Slichter Award, 1997, Citation: “For developing novel optical probes of polymer properties and effectively transferring these measurement methods to industry to control polymer processing”
Award of Excellence, Federal Laboratory Consortium for Technology Transfer, 1997, Citation: “For development of new instruments to monitor manufacturing processes and the transfer of that technology to U. S. manufacturers”
Fellow of the Society of Plastics Engineers, 1997, Citation: “For significant contributions to measurement science and application of these developments to polymer processing”
Future Technology Award from Maro publications, 1999, Citation: “In-Situ measurement of shrinkage opens up possibilities for automation in molding”
Future Technology Award from Maro publications, 2000, Citation: “Electrical measurements are strategically useful for online testing and process monitoring”
2005 Best paper award, sponsored by DOW Chemical Company, for “Temperature Gradients in the Channels of a Single Screw Extruder”
International Research Award sponsored by The Society of Plastics Engineers, 2006, Citation: “For outstanding achievements in research and development of process monitoring measurements and the application of new measuring concepts to study and understand manufacturing problems”
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| Publications: |
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Publications and Patents Summary
He has published over 100 technical papers and reports in the fields of polymer science and polymer processing, and he has been awarded seven instrument patents.
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Selected Publications and Publishers
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- Review of Scientific Instruments
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- Polymer
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- Polymer Engineering and Science
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| Government Experience: |
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| Years |
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Agency |
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Role |
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Description |
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1963 to 2005
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National Institute of Standards and Technology
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Research Physicist
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He proposed, initiated and directed research programs in polymer science. He developed data analysis protocols and interpreted data in terms of physical models. He presented lectures at national and international scientific meetings. He prepared manuscripts for publication in scientific journals.
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| Selected Consulting Examples: |
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He founded and chaired the New Measuring technology for Polymer processing Consortium which was based at NIST from 1993 to 1998. This consortium was composed of leading polymer industry members from Dow Chemical, Rohm and Haas, DuPont, 3M Co. and Dynisco. New measuring technologies based optical methods were developed. These included an optical sensor for monitoring polymer injection molding, a fluorescence anisotropy sensor for measuring molecular orientation, a temperature sensor based on fluorescence for measuring temperature gradients in flowing liquids. During this period, he discovered a new class of fluorescent dye, band definition dyes, that can be used as temperature probes.
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He consulted with Exxon Mobil and lead the development of a fluorescence anisotropy sensor that could be used for on-line detection of molecular orientation during the biaxial stretching of polypropylene films. The sensor also included temperature monitoring capabilities based on properties of fluorescence spectra. The sensor was installed on a tenter oven manufacturing line and used to evaluate processing conditions.
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He consulted with Dow Chemical Co. on two projects: to measure resin temperature during the reactive extrusion processing of barrier film product, and to measure the resin temperature gradfients in a resin flowing in the screw thread during single screw extrusion.
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He consulted with Chemical ElectroPhysics Corp. on the design and construction of an innovative dielectric slit die that is used to monitor dielectric, optical, ultrasonics and rheological properties of polymer composites during compounding. He received a patent for this instrument design in 2006 (US patent no. 7,143,637).
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He has consulted with the U.S. Air Force and The U. S. Naval Weapons Lab. For the Air force, he designed piezoelectric gages to monitor ordnance explosions and for the Navy he established the protocol for using fluorescent dyes to measure the quality of mixing of solid propellants.
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Recent Client Requests:
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Expert for consulting on Plastics formulation for and optical imaging application.
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Expert in dielectric measurement for consulting on dielectric constant of solids, semi-solids, and liquids.
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Polypropylene or General Polymer extrusion expert needed for consulting regarding a random defect in PP tubing extrusion .
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Expert in polymer recipe & operating parameters to make low molecular weight styrene-maleic anhydride "SMA" resin.
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Expert in fluorescence imaging for consulting on design of a fluorescence imaging system.
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Click the green button above to contact
Expert for a free initial screening call regarding your expert consulting needs.
Expert is available for consulting to corporate, legal and government clients.
Remember, your initial screening call to speak with
Expert is free.
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Expert Witness Experience Summary:
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His previous employment limited his ability to participate in the litigation consulting.
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Click the green button above to contact
Expert for a free initial screening call regarding expert testimony,
litigation consulting and support, forensic services, or any related expert witness services.
A few litigation needs include product liability, personal injury, economic loss, intellectual property
(patent, trademark, trade secret, copyright), and insurance matters. Remember, your initial screening
call to speak with
Expert is free.
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| International Experience: |
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Country / Region |
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Summary |
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2001 to 2004
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United Kingdom
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He consulted with Professor Philip Coates and his students at the University of Bradford regarding the design and use of optical fiber sensors for monitoring polymer processing. His contribution to this project was offering guidance regarding material selection, sensor design and sensor dimensions.
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2009 to
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India
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He consults with Prof. Ghosh at the India Institute of Technology, Delhi regarding the monitoring of polymer nanocomposites properties during compounding.
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In the area of polymer process monitoring, he has been at the forefront of new developments in this field for the past twenty years. In his position at a federal laboratory he was able to view and participate in the movement, trends and changes in processing and process monitoring. His research program at NIST was a national model for the advances in the field of polymer process monitoring. He constantly focused on the goal of eliminating process errors and off-spec products in order to increase productivity and product quality.
Click the green button above to contact
Expert for a free initial screening call regarding your marketing research, industry research, and company
research needs. For research needs involving multiple experts or secondary research,
a Research Director can be assigned to coordinate the work into a custom report for you as a potentially quicker
and more cost effective alternative to doing this work yourself or hiring a boutique consultancy.
Remember, your initial screening call to speak with
Expert is free.
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| Additional Skills and Services: |
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Training/Seminars
Over the course of his career as a polymer scientist/physicist, he has presented many lectures (dozens) on the topic of polymer physics, process monitoring and process instrumentation. These lectures have been at industry (e.g. DuPont, GE, Dow Chemical) and University (e.g. University of Virginia, William and Mary, University of Akron) locations. He has organized symposia at NIST and at national and international meetings. Recent topics of these lectures include: Applied Physics in the Industrial Environment, Dielectric Properties of Polymer/Clay Nanocomposites, Fluorescence Based Temperature Measurements During Polymer Processing, Molecular Orientation of Polymer Films Using Fluorescence Anisotropy Measurements, A Dielectric Slit Die for Monitoring Electrical, Optical and Rheological Properties During Polymer Extrusion.
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Supplier and Vendor Location and Selection Supplier/Vendor selection was a continuing part of his every day responsibilities over a 45 year research career. This involved negotiations about specifications, delivery and price.
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Other Skills and Services
His skills span over a range of activities, designing equipment, interacting with suppliers, materials selection, writing proposals, carrying out experiments, data acquisition techniques, data analysis, constructing mathematical models, writing technical papers.
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Education
