Carbon Fiber-Carbon Matrix Composite Material

Dr. James V. Beck
Department of Mechanical Engineering

Carbon fiber-carbon matrix composite material is a very attractive material for advanced aerospace and automotive applications. It might be used on the National Aerospace Plane, brakes of advanced military and commercial aircraft and in the engines of future automobiles and trucks. It can withstand high temperatures and has relative high thermal conductivity. In fact, its thermal properties are the reason for some of its applications.

A grant from Sandia National Laboritories (Aug. 1992 - Sept. 1993) for the transient, two-dimensional measurement of thermal properties of a carbon-carbon composite material was extended through 1993-1994 CMSC REF funding. The purpose was to investigate the use of CVD diamond film at the carbon-carbon surface for temperature measurement and providing the heat source. During the support, diamond was deposited on the carbon-carbon by Prof. A. Aslam's group in Electrical Engineering but more work needs to be done in that aspect. Nevertheless thermal conductivity and volumetric heat capacity were measured for the carbon-carbon, using another method of heating.

Many one- and two- dimensional experiments were performed. The temperature range of 25 to 600 degrees Celcius was investigated in an air atmosphere. The research had analytical aspects because it employed parameter estimation methods in analyzing the transient data. The parameter estimation concepts are powerful because complex experiments are coupled with complex models to determine several parameters (or even a function) from the same experiment. In the present case, two orthotropic components of the thermal conductivity and volumetric heat capacity were measured simultaneously. Some of these were simultaneously found as a function of temperature from the transient experiments.

The work is reported in the following publication: K. Dowding, J. Beck, A. Ulbrich, B. Blackwell and J. Hayes, "Estimation of Thermal Properties and Surface Heat Flux in a Carbon-Carbon Composite Material", AIAA-ASME Thermophysics Conference, Colorado Springs, CO June 1994.

This is to be presented orally at the Thermophysics Conference June 20, 1994. An expanded version of it was also presented at the Sixth Inverse Problems in Engineering Seminar, Cincinnati, OH (June 12 and 13, 1994). It was also presented (June 14, 1994) before a few engineers at Wright-Patterson Air Force Base, where further funding may be forthcoming on this research.

One part of this research is the determination of the surface heat flux from temperature measurements. One method (that Prof. Beck invented) is called the function specification method. Some international talds and papers on this are to be given this summer as indicated in the next column. This work has been partially supported by the Composite Material and Structures Center.

J.V. Beck and B. Blackwell, "Function Specification Method with New Specified Functions", to be presented at the Second International Conference on Dynamic System Indentification and Inverse Problems, St. Petersburg, Russia, Aug. 22-25, 1994.

J.V. Beck, "Function Specification Method for the Solution of the Solution of the Inverse Heat Conduction Problem", invited talk and paper to be presented at the SIAM-GAMM Conference on Inverse Diffusion Problems at St. Wolfgang, Austria, June 27-Aug. 2, 1994.

Polymer-Clay Nanocomposite Materials

Tie Lan and Dr. T.J. Pinnavaia
Department of Chemistry

Clays have been used for decades as fillers for a variety of plastics and rubbers. In most cases these inexpensive components simply saved on polymer costs and play no functional role in determining the performance properties of the final composites. However, researchers at Toyota have recently discovered a new family of polymer-clay composite materials that promise to revolutionize clay applications in composite formulations.

Recognizing that clay structures consist of stacked sheets of silicate anions approximately 1 nm-thickness, the Toyota group set out to exfoliate the stacked structure into a dispersion of high aspect ratio sheets within the polymer matrix. They were successful in achieving such dispersions in nylon using alkylammonium exchanged forms of montmorillonite and other smectitetype clays. Whereas convetional polymer-clay composites retained coherent stacking of the layered building blocks characteristic of the clay crystallites, the new nylon-clay composites consisted of 1.0 nm-thick clay sheets separated by 20-30 nm of polymer. This exfoliation process increased the aspect ratio of the embedded particles from a value of 20 for the stacked crystallites to values of 2000 in the nanocomposites. The effect of the high aspect ratio platelets on the performance properties of the nylon was truly spectacular. For instance, the addition of 5 wt% montmorillonite to nylon-6, increased the tensile strength and modulus, respectively, from 68.6 MPa and 1.11 GPa for the pristine polymer to 97.2 MPa and 1.87 GPa for the composite. Also, the thermal and rheological properties of the nylon were improved significantly by nanocomposite formation. An increase in heat distortion temperature from 65 degrees Celcius for nylon-6 to 152 degrees Celcius for a nylon-clay hybrid was achieved at a 5 wt% clay loading.

Owing in part to the long-standing interest in layered materials at MSU, a multidisciplinary group has undertaken a study of polymer-clay nanocomposites in order to better define the intercalation chemistry of clay towards different polymer compositions and to elucidate the factors responsible for the enhanced performance properties of the composites. The group, which is funded jointly by the Composite Materials and Structure Center and the Center for Fundamental Materials Research, includes L.T. Drzal in Chemical Engineering, P.M. Duxbury in Physics, J.R. Giacin and R.J. Hernandez in Packaging, and T.J. Pinnavaia in Chemistry.

The Pinnavaia group has recently reported a new type of polyether-clay nanocomposite by the self-polymerization of the diglycidyl ether of bisphenol A in the galleries of acidic alkylammonium ion exchanged forms of montmorillonite. Delamination of the montmorillonite clay in the polymerized epoxy resin was confirmed by X-ray powder diffraction and TEM. The micrographs for a 5 wt% (H3N(CH2)11COOH)+ clay-polyether nanocomposite, as shown in Figure 1, revealed that the micron-sized clay tactoids had been expanded by the polymer into accordion-like packets in which the interlayer spacings range up to 2,000 A. Studies of the possible applications of these unique polyether-clay nanocomposites is in progress.

Polyimide-clay hybrids represent another type of a polymer-clay nanocomposite currently under investigation. These nanocomposites have been prepared by intercalation of the organoclay by a polyamic acid dissolved in an organic solvent subsequent thermal conversion to the polyimide. In contrast to the completely exfoliated polyether-clay system, the polyimide system contains regularly intercalated clay aggregates in the polymer matrix. Although face-face clay layer aggregation is extensive, the clay- polyimide hybrid composite films exhibit greatly improved CO2 barrier properties at low clay content, as shown in Figure 2. Less than 8.0 vol% clay results in almost a ten-fold decrease in permeability. A self-similar or fractal dispersion of the clay platelets in the polyimide matrix, as shown in Figure 2, may explain the barrier property enhancement.

Figure 2. CO2 permeability of polyimide-clay composites prepared by curing CH3(CH2)17NH3+ montmorillonite-polyamic acid films at 300 degress Celcius. The measurements were performed on films of 2.5 cm diameter and 2.5 mm thickness. Curve B was generated by least-squares fitting of the permeability equation to the experimental data. Curves A and C are calculated for fillers with W/T aspect ratios of 20 and 2,000, respectively. Inset illustrates a possible self-similar aggregation mechanism for the clay plates.

References:

1. Fukushima, Y.; Inagaki, S. J. Inclusion Phenomena, 1987, 5, 473.

2. Kojima, Y.; Usuki, A.; Kawasumi, M.; Okada, A; Fukushima, Y.; Kurauchi, T.; Kamigaito, O. J. Mater. Res., 1993, 8, 1185.

3. Wang, M.; Pinnavaia, T.J. Chem. Mater., 1994, 6, 468.

4. Lan T.; Kaviratna, P.D.; Pinnavaia, T.J. Chem. Mater., 1994, 6, 573.

Handling Your Invention

By the Office of Intellectual Property

What are intellectual properties?

Intellectual properties are intangible products of the mind. Specifically, they are ideas and the way they are represented. Such things as invetions, publications and other works of scholarship, videotapes, computer programs, or works of art are intellectual properties. Intellectual properties can be protected by means of a copyright, trademark, and patent.

In becoming an employee of Michigan State University, you agree to give certain intellectual properties to the university, in return for which the university will do its best to develop and market them and share royalty receipts with the inventor and their department or unit. The authority is vested in the President of the university, who in turn has delegated it to the Vice President for Research and Graduate Studies. The Office of Intellectual Property (OIP) administrates this function by evaluating, patenting, and then transferrng protected inventions into the marketplace. In doing so, OIP contributes to the fulfillment of Michigan State University's land-grant committment to the extension of applied knowledge.

This brief article explains the preliminary actions necessary to protect an invetion. Other processes of protection-patenting and licensing-will be explained in separate articles. If you need additional information, please direct your intellectual property questions to:

Office of Intellectual Property

Michigan State University

238 Administration Building

East Lansing, MI 48824-1406

Telephone (517)355-2186

Fax (517)432-1171

What is an invention?

The dictionary defines an invention as the creation of something not previously in existence that is, an original device or process. U.S. Patent Law is even more specific: an invention is "a device or process that is not only novel and useful but is recognized by masters of science as such an advance, and reveals more that the skill of expert artisans or mechanics in discovering new and useful gadgets or processes of wide commercial application."

Can my invention be patented?

To be protected by patent, an invetion must possess the following qualities:

Novelty. Your invention must be new-that is, it must be different from "prior art." Prior art is defined as the total amount of technical experience and knowledge of every person who has ever lived. It also means that you, the inventor, may not have published it, put it in public use, or offered it for sale for more than one year before you apply for a United States patent.

Utility. The invention must be useful.

Nonobviousness. The invention must not have been obvious to anyone of ordinary skill in the invention's art at the time the invention was made.

To receive a patent, you must also disclose enough information about your invention that others are able to use it. The U.S. govenment sees the granting of patents as an incentive to invention disclosure-a way to add to the amount of available knowledge.

What is invention disclosure?

Invention disclosure is sharing sufficient information for another person to carry out or duplicate your invention. It is the first step in the patenting process. Such disclosure should be accompanied by a written agreement of confidentiality. Improper disclosure will result in losing all rights to patenting in foreign countries. Failure to file a patent application with the U.S. Patent and Trademark Office within one year of improper disclosure results in complete loss of patenting.

Generally you may disclose your invention to fellow university colleague without a written agreement of confidentiality. You may make disclosure to someone outside the MSU community without jeopardizing invention patentability if proper confidentiality requirements are in place. The MSU Confidential Disclosure Agreement provides these confidentiality requirements. When appropriately signed at MSU and by the potential recipient's organization, this agreement will prevent loss of foreign patentability and obviate the U.S. patent timeline.

In order for Michigan State University to begin the process of protecting, patenting, and transferring your invention, your must make proper disclosure to the MSU Office of Intellectual Property by means of and Invention Disclosure Form, available from OIP.

What is Michigan State University's patent policy?

The patent policy defines what intellectual properties you have agreed, by becoming an employee of the university, to give to the university. This policy is stated in the faculty handbook.

When should I make an invention disclosure to OIP?

The sooner you submit your invention disclosure to our office, the more we will be able to assist you. Your invention need not be complete when you first disclose it to OIP. Additional information can be added to the disclosure files as it is developed, until your invention is complete. Early submission allows us to review the invention and initiate inquiries to determine its commercial potential before you invest further time and effort in it. Early submission also provides us the opportunity to discuss the handling of the invention and, perhaps, assist you in locating an industrial research sponsor for continued invention development.

The early submision of your invention disclosure could also result in earlier filing of the patent application in the U.S. Patent and Trademark Office. An earlier filing date may be important if a similar invention is being developed elsewhere.

What information do I need to provide to complete an invention disclosure?

You will need to provide:

To be patentable, your idea must be somehow reduced to practice. You can make a working model, but this is not necessary. A more common course of action is to include in your patent application clear and complete drawings and descriptions of the invention.

What will OIP do with my invention disclosure?

First, they will perform a search to determine if your invention is patentable. If it is patentable, OIP may or may not pursue the patent in the name of Michigan State University. This determination will be based on a number of factors, including potential commercial value. You will be involved in making this patent filing decision. If a patent is not pursued, the university will return the assigned patent rights to you upon your written request.

If the OIP pursues the patent on your invention in the name of the university, it will assume all costs related to obtaining the patent, and, once the patent has been obtained, will investigate possibilities for marketing the invention. Usually this takes the form of licensing all or part of the patent rights.

What if my invention is not patentable?

Inventions that are not patentable may still be valuable. There may be a great deal of "know-how" about your invention. Basically, know-how is "knowing how" to do something using this knowledge. The university could market this know-how or it could return the invention to you.

Will the patent process interfere with my publishing my research? Because of the requirement that an invention submitted to the U.S. Patent and Trademark Office may not have been disclosed to the public more than one year before the patent applications submitted, you must be cautious about publishing your research if you wish to seek a patent. However, we do our best to facilitate the patent process so that publishing research is not compromised. One the patent application has been submitted, you can publish as much and as often as you want.

How can I protect my patentable inventions?

Make sure you keep good records of your work while you are creating your invention. A detailed research notebook is very important in documenting the inventive progress. As you invent, you should make sketches and detailed written descriptions of your activities, numbering and dating them as you go.

Your notebook record should be reviewed by witnesses as your go along, even daily. Witnesses cannot be coinventors. It's best to have the same people witness your later work who witnessed your original conception of the invention. Good potential witnesses might be the chairperson of your department or institute or a departmental colleague who is not a part of your project. Office support staff members are generally not appropriate witnesses.

An accurate record of important dates is critical. Be sure to note the date the invention is conceived - that is, the date you first present a written description, sketch, drawing, or model of your invention to a witness - as well as the date the invention is reduced to practice either by the filing of a patent application describing the invention or by making a working model.

You should also make note of the date the invention is first put in public use - that is, the date the information is first disclosed outside the university community. Once any of these occur, there is a time limit of one year in which you may file for a patent application.

As a researcher, it's particularly important for you to keep in mind that you have one year from the date your first disclose your research findings in a "printed publication" to apply for a patent. As defined by patent law, "printed" can mean printed, typed, or handwritten, and "published" simply means made available to the public. If your invention is disclosed to the public more than one year before application for patent is made, this disclosure will be considered prior art and your invention will not be patentable.

Golf Scramble A Big Success

Arlene Klingbiel and Mark Allen, CMSC

Although, it was a hot and humid day, the rain clouds cleared away for the 6th annual CMSC Golf Scamble held on July 20th at Forest Akers East. This years scramble boasted a record turnout of thirty four participants. Everyone attending enjoyed a funfilled afternoon of golf, followed by a cookout at Dr. Drzal's house in Okemos. Congratulations go to the following winners: Ther was a tie for the lowest score of 40 between the teams of Terry Casey & Arlene Klingbiel, and Peter Drzal & John Lloyd. Names were drawn making Terry and Arlene the official lowest score winners. Dan Hook and James Fernandes captured the highest score of 53. James Fernandes also won the closest to the pin contest on hole #4. In fact, he was the only person to get on the green. Jeff Shull took the longest Drive on hole #6. Finally, Diana D'Angelo was the winner of the longest putt contest on hole #9. Special thanks go to Pro-Image for sponsoring hole #6 (longest drive), to Dan Hook for all of the time and effort he put into organizing the event, to Dr. Drzal for inviting everyone to his house afterwards, and thanks to everyone who participated in this memorable event. We hope to see all of you again next year.

CMSC Calendar

Technomic Seminar - Test Methods for Composite Materials - 3 day seminar - how to select and use test methods; wide range of methods; speciment preparation and failure modes; physical property measurements; evaluation of constituent materials.
Location: San Diego, CA
Date: 7/26-28/94

CALL FOR PAPERS - AIChE Summer National Meeting - Application of Chemical Engineering Fundamentals to Environmental Problems (Environmental Issues of Energy Conservation Technology, Energy from Solid Waste)
Location: Denver, CO
Date: 8/14-17/94

CALL FOR PAPERS - Summer AIChE meeting. Design for the environment-incorporation of pollution prevention into Chemical Engineering curriculum.
Location: Denver, CO
Date: 8/14-17/94

American Institute of Chemical Engineers - 1st International Particle Technology Forum (Exchange of Education, Research in the field of Particle Technology)
Location: Denver, CO
Date: 8/17-19/94

CALL FOR PAPERS - University of New Orleans - 1st International Conference on Composite Engineering (ICCE/1). (Conference goals: Bridge gap between mechanics and materials science of composites; encouage interactions between basic and applied research group composites; assess the state of the art in modeling and analysis of modern composites structures and materials relevant to the need of the commercial or defense industries).
Location: New Orleans, LA
Date: 8/28-31/94

American Society for Composites - ASC 9th Technical Conference (Processing Science and Manufacturing, Mechanics, Design and Applications, Materials Science, and Durability).
Location: Newark, DE
Date: 9/20-22/94

CALL FOR PAPERS - International Body Engineering Conference (IBEC) - (will focus on the best in worldclass total automotive body systems-design, materials, engineering, and manufacturing practices on a global basis).
Location: Detroit, MI
Date: 9/26-29/94

Composite Materials and Structures Center
College of Engineering
Michigan State University
East Lansing, MI 48824-1326

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