Arrays of long carbon nanotubes for fiber spinning

Abstract

An array of long carbon nanotubes (i.e. an array where the average length of the nanotubes is greater than 0.5 millimeters) is prepared by exposing a supported catalyst at elevated temperature to a gas mixture of hydrocarbon, inert gas, and a relatively low percentage of hydrogen. Addition of water vapor to the gas mixture may result in an increase in the length of the nanotubes, an increase the rate of growth, and a decrease in contamination of the array by amorphous carbon. The temperature and growth time are also chosen to minimize the amount of amorphous carbon that forms on the array. Fibers spun from the array have a higher tensile strength compared to known CNT fibers.

Description

RELATED APPLICATIONS [0001] This application is a continuation-in-part of U.S. patent application Ser. No. 11 / 051,007 filed Feb. 4, 2005, and also claims the benefit of U. S. Provisional Application Ser. No. 60 / 620,088 filed Oct. 18, 2004, both incorporated by reference herein.STATEMENT REGARDING FEDERAL RIGHTS [0002] This invention was made with government support under Contract No. W-7405-ENG-36 awarded by the U.S. Department of Energy. The government has certain rights in the invention. FIELD OF THE INVENTION [0003] The present invention relates generally to carbon nanotubes, and more particularly to the preparation of a supported array of long carbon nanotubes, to a catalyst for preparing the array, and to fibers spun from the array. BACKGROUND OF THE INVENTION [0004] Individual carbon nanotubes (CNTs) are at least one order of magnitude stronger than any other known material. CNTs with perfect atomic structures have a theoretical strength of about 300 GPa [1]. In practice carbo...

AI Technical Summary

Benefits of technology

[0015] The invention also includes a spun fiber of carbon nanotubes having a tensile strength S, wherein S≧1 GPa.

Problems solved by technology

In practice carbon nanotubes do not have perfect structures.

Due to difficulties in growing long CNT arrays that are conducive to spinning, CNT yarns so far can only be drawn from arrays of less than 300 μm long, and have a tensile strength of only around a few hundreds of MPa.

A problem with current procedures for preparing CNT arrays is a requirement of a large amount of hydrogen gas in the precursor.

Hydrogen is relatively expensive and can be dangerous when large amounts are used in the laboratory and industrially.

Importantly, CNT arrays of the prior art are generally not good precursors for fibers because they tend to be contaminated with amorphous carbon.

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