Composite material of continuous fiber and ultra high molecular weight polyethylene

Abstract

A composite material composed of continuous high strength fibers such as carbon, aramid or glass, and ultra high molecular weight polyethylene (UHMW PE), wherein the UHMW PE comprises a continuous matrix among and surrounding the fibers. The resultant composite material exhibits extraordinarily high strength, stiffness and other fiber dominated properties in the directions parallel to the fibers and exhibits its lowest strength and stiffness in directions perpendicular to the fibers. It also exhibits superb abrasion resistance, good impact strength, excellent chemical resistance, a low coefficient of friction and other beneficial properties of UHMW PE.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority under 35 U.S.C. § 119 from provisional application Ser. No. 60 / 578,420, filed Jun. 9, 2004, and entitled “A Composite Material of Continuous Fiber and Ultra High Molecular Weight Polyethylene”.FIELD OF THE INVENTION [0002] This invention relates generally to the art of composite materials, more particularly to composite materials comprising thermoplastics and high strength fibers. BACKGROUND OF THE INVENTION [0003] Thermoplastics are plastics that are made by heating resin pellets or powders (the raw material) until they melt, molding the material to a desired shape, and then resolidifying the material through a cooling process. Because the chemistry of the plastic does not change, this process can be performed multiple times. In other words, thermoplastics can be reprocessed or recycled with additional heating and cooling. Additionally, the manufacturing process for thermoplastic products can be as quic...

AI Technical Summary

Benefits of technology

[0020] The techniques described above, however, until the present invention, did not particularly work well with UHMW plastics. It is an object of the invention to provide a composite material of continuous fiber and ultra high molecular weight polyethylene (UHMW PE) exhibits many improved physical properties in comparison to both unreinforced and short fiber reinforced UHMW PE. Another object of the invention is to improve strength and stiffness in the fiber direction as well as thermal and electrical conductivity when a highly conductive fiber is employed. It is yet another object of the invention to provide a composite that exhibits many of the outstanding characteristics of unreinforced UHMW PE, such as excellent abrasion resistance, low coefficient of friction and high PV.

Problems solved by technology

The use of higher percentages of fiber and / or longer fibers is typically avoided because of difficulties achieving good flow of the mixture and good uniform dispersion and distribution of the fibers, unacceptable accumulation of the fibers in the nozzle of the injection molding equipment, and unacceptable reduction in toughness and impact strength in the product.

There is possibly, however, a characteristic loss of impact strength in the short fiber FRP product compared with the unreinforced thermoplastic product as reported with respect to polycarbonate in U.S. Pat. No. 3,577,378.

This high molecular weight provides UHMW PE with exceptional impact strength and abrasion resistance; however, it also results in special well known processing characteristics which preclude use of standard extrusion and molding techniques.

In fact, when attempting to injection mold UHMW PE, the extreme pressures result in shear-degradation of the polymer.

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