US3841079A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Carbon filaments capable of substantial crack diversion during fracture
Assignee: SUBJECT TO AGREEMENT RECITED SEE DOCUMENT FOR DETAILS
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Filing: 1972-04-17
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Granted: 1974-10-15
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Expires: 1992-04-17
Abstract
Abstract An improved carbon filament is provided having an internal structure capable of increasing the amount of work required to break the filament. The internal structure of the carbon filaments of the present invention as evidenced by the means apparent fracture surface energy of the same facilitates the exhibition of satisfactory strength properties even if accompanied by the presence of gross inhomogenities and structural flows such as commonly encountered in carbon filaments of the prior art.
Inventors
- 👤 M Ram
- 👤 J Riggs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 04:56
CPC Classifications
D; D01; D01F; D01F9/00; D01F9/08; D01F9/12; D01F9/14; D01F9/32; D01F9/328; D01F6/00; D01F6/02; D01F6/18; D01F6/28; D01F6/38; D01F9/20; D01F9/21; D01F9/22; D01F9/225
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
66 words
AN IMPROVED CARBON FILAMENT COMPRISING AT LEAST 90 PERCENT CARBON BY WEIGHT HAING AN UNSUALLY HIGHLY DEVELOPED MICROPOROUS AND FIBRILLAR INTERNAL STRUCTURE SUBSTANTIALLY COEXTENSIVE WITH THE LENGTH OF SAID FILAMENT CAPABLE OF DIVERTING A PROPAGATING CRACK DURING FRACTURE THEREBY INCREASING THE AMOUNT OF WORK REQUIRED TO BREAK THE FILAMENT AS EVIDENCED BY A MEAN APPARENT FRACTURE SURFACE ENERGY OF AT LEAST 50 JOULES PER SQUARE METER.
Claim 2
Dependent Claim
66 words
AN IMPROVED CARBON FILAMENT COMPRISING AT LEAST 90 PERCENT CARBON BY WEIGHT HAING AN UNSUALLY HIGHLY DEVELOPED MICROPOROUS AND FIBRILLAR INTERNAL STRUCTURE SUBSTANTIALLY COEXTENSIVE WITH THE LENGTH OF SAID FILAMENT CAPABLE OF DIVERTING A PROPAGATING CRACK DURING FRACTURE THEREBY INCREASING THE AMOUNT OF WORK REQUIRED TO BREAK THE FILAMENT AS EVIDENCED BY A MEAN APPARENT FRACTURE SURFACE ENERGY OF AT LEAST 50 JOULES PER SQUARE METER.
Claim 3
Dependent Claim
17 words
An improved carbon filament according to claim 1 wherein said filament is present in a multifilament yarn.
Claim 4
Dependent Claim
17 words
An improved carbon filament according to claim 1 wherein said filament is present in a multifilament tow.
Claim 5
Dependent Claim
19 words
An improved carbon filament according to claim 1 wherein said filament comprises at least 95 percent carbon by weight.
Claim 6
Dependent Claim
19 words
An improved carbon filament according to claim 1 wherein said filament comprises at least 98 percent carbon by weight.
Claim 7
Dependent Claim
23 words
An improved carbon filament according to claim 1 which exhibits a mean single filament Young''s modulus of about 20 to 50 million psi.
Claim 8
Dependent Claim
16 words
An improved carbon filament according to claim 1 wherein the cross-sectional configuration thereof is substantially round.
Claim 9
Dependent Claim
24 words
An improved carbon filament according to claim 1 which exhibits a mean apparent fracture surface energy of at least 60 joules per square meter.
Claim 10
Dependent Claim
24 words
An improved carbon filament according to claim 1 which exhibits a mean apparent fracture surface energy of at least 70 joules per square meter.
Claim 11
Dependent Claim
82 words
An improved carbon filament comprising at least 95 percent carbon by weight which exhibits a mean single filament Young''s modulus of about 20 to 50 million psi and has an unusually highly developed microporous and fibrillar internal structure substantially coextensive with the length of said filament capable of diverting a propagating crack during fracture thereby increasing the amount of work required to break the filament as evidenced by a mean apparent fracture surface energy of at least 70 joules per square meter.
Claim 12
Dependent Claim
82 words
An improved carbon filament comprising at least 95 percent carbon by weight which exhibits a mean single filament Young''s modulus of about 20 to 50 million psi and has an unusually highly developed microporous and fibrillar internal structure substantially coextensive with the length of said filament capable of diverting a propagating crack during fracture thereby increasing the amount of work required to break the filament as evidenced by a mean apparent fracture surface energy of at least 70 joules per square meter.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |