Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Reexamination Certificate
1999-08-16
2001-10-09
Weisberger, Richard (Department: 2165)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
C264S210100, C264S211120, C264S211130
Reexamination Certificate
active
06299812
ABSTRACT:
BACKGROUND OF THE INVENTION
Innovations in materials have driven much of the technological progress throughout the century. Today, the potential applications of a new unforeseen pure molecular form of carbon known as carbon nanotubes, is engendering tremendous excitement across the scientific community. Since their discovery, reports of their ever more outstanding and exciting properties seems to foreshadow the advent of the new and quite remarkable carbon age. Many countries have now identified such molecules as a strategic commodity and are making major commitments toward their production. Such countries see potential applications of such novel pure carbon molecules across their spectrum of industry. The usage of carbon nanotubes in high-tech composites alone offers tremendous potential. Theoretical calculation of stress and strain for some carbon nanotube molecules indicate that as carbon substitutes in high-tech composites they could provide an even greater leap forward in material advantages than existing carbon composites have had over previously used materials. Already, such carbon composites have revolutionized aircraft design and in the process given the United States significant military and economic advantages. It is precisely for such reasons that, worldwide, a push is on to develop and mass produce this new carbon form. At ⅙th the weight of steel and 50 to 150 times stronger, carbon nanotubes are, in essence, an ideal fiber for enhanced composite materials. Previous efforts to commercialize carbon nanotubes have revealed serious production problems.
It would represent an advance in the state of the art if a method were developed which could facilitate the manufacture of products with fibers, such as carbon nanotubes and/or nanowires, nanoropes, or other ultrasmall fibers. It is to such an improved method for facilitating the manufacture of products that the present invention is directed.
SUMMARY OF THE INVENTION
The present invention is a method for mass producing fibers/composite material having an anisotropic structure that can be specifically utilized in forming various desirable products, such as a composite shield for electromagnetic radiation, for example. When the method is utilized to produce elongate fibers, the fibers possess highly aligned internal fibers, such as carbon nanotubes positioned parallel to the length of the fiber. The high degree of parallel alignment of the carbon nanotubes impart electrical conductivity significantly higher than that of other polymers made electrically conducting by the addition of metal or carbon powders. This is especially true given that certain nanotubes, i.e., those having a ring pattern in the graphitic wall of the nanotubes align with the carbon nanotubes axis, are used. Nanotubes with this pattern have conductivity approaching that of gold.
Broadly, the fibers/composite material is produced by mixing an effective amount of fibers with a matrix material to form a mixture containing from about 96 weight percent of the fibers to parts per billion (ppb) of the fibers and wherein the fibers are randomly oriented in the deformable mixture. The mixture is then passed through an orifice or capillary (e.g. extruded), or pulled or stretched to form an extrudate and to create an anisotropic structure, e.g. an enhanced orientation/alignment of the fibers along the longitudinal axis of the extrudate. Thereafter, pressure can be applied about the extrudate to substantially compress the fibers in the extrudate and to enhance the anisotropic structure of the extrudate. The fibers/composite material is a highly-moldable, composite material with significant potential in military applications and which by the proper choice of components may have desirable properties, such as ultra-strength, an increased conductivity orders of magnitude over that of even a normally conductive polymer, an increased semi-conductive property, or an enhanced optical property.
Other advantages and features of the Applicants' unique methods and products produced thereby will become apparent to those of ordinary skill in the art upon a reading of the following detailed description with reference to the attached drawings and appended claims.
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Murphy, J, Reinforced Plastics Handbook, p. 167, 1994.
Harwell Jeffrey H.
Newman Gerard K.
Shambaugh Robert L.
Dunlap Codding & Rogers P.C.
The Board of Regents of the University of Oklahoma
Weisberger Richard
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