Patent US3660140A successfully refreshed from Google Patents.
US3660140A
Expired / Lapsed
US
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Treatment of carbon fibers
Assignee: RTX Corp
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Filing: 1970-06-18
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Granted: 1972-05-02
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Expires: 1990-06-18
Abstract
Abstract A method of treating high modulus, high strength carbon fiber to improve its bonding characteristics in a resin matrix comprising immersing the fiber in concentrated nitric acid for 4- 8 hours at refluxing temperature.
Inventors
- 👤 Daniel A Scola
- 👤 Hilton A Roth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:24
CPC Classifications
D; D01; D01F; D01F11/00; D01F11/10; D01F11/12; C; C08; C08J; C08J5/00; C08J5/04; C08J5/06; Y; Y10; Y10S; Y10S264/00; Y10S264/19
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
15 words
The method of claim 1 wherein the fiber is immersed from 4 through 8 hours.
Claim 2
Dependent Claim
12 words
The method of claim 2 wherein the acid is 70% nitric acid.
Claim 3
Independent Claim
70 words
A method for improving the bonding characteristics of high strength, high modulus carbon fibers with resin matrix material without significantly degrading the mechanical properties of the fibers which comprises, prior to impregnating the carbon fibers with said matrix material, subjecting said fibers to the action of concentrated nitric acid at refluxing temperature for a period of time sufficient to increase the specific surface area of the fibers to 3.4-7.3 m2/g.
Claim 4
Independent Claim
100 words
A method for improving the bonding characteristics of high strength, high modulus carbon fibers with resin matrix material without significantly degrading the mechanical properties of the fibers which comprises, prior to impregnating said carbon fibers with said resin matrix material, exposing said fibers to the action of concentrated nitric acid at refluxing temperature to cause an increase in the number of active sites at the fiber surface as measured by NaOH absorbed per unit area and continuing the exposure of the fiber to the acid at least until the number of active sites at the fiber surface ceases to increase.
Claim 5
Independent Claim
52 words
A method for the production of a carbon filament-resin composites having a high resistance to shear failure while maintaining high flexural strength comprising, exposing high modulus, high strength carbon filaments to concentrated nitric acid at refluxing temperature for at least 4 hours, and impregnating said treated carbon filaments in a resin matrix.
Claim 6
Dependent Claim
13 words
The method of claim 6 wherein said filaments are exposed for 4-8 hours.
Claim 7
Dependent Claim
13 words
The method of claim 6 wherein said resin is epoxy or polyimide resin.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-02 | 1975-11-01 | 1976-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-02 | 1979-11-01 | 1980-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-02 | 1983-11-01 | 1984-05-02 | $7700.00 | Window Closed / Lapsed |