US4180648A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Crystalline polyimides
Assignee: National Aeronautics and Space Administration
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Filing: 1978-05-15
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Granted: 1979-12-25
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Expires: 1998-05-15
Abstract
Abstract Novel aromatic crystalline polimides are disclosed that are synthesized from polyamide-acid and when heated to 200 DEG to 300 DEG C. become cyclized to afford an opaque polymer which by X-ray diffraction of the unoriented film exhibited 47 percent crystallinity. Differential Scanning Calorimetry (DSC) indicates a melt at 425 DEG C. with no glass transition in these crystalline polyimides.
Inventors
- 👤 Terry L. St. Clair
- 👤 Anne K. St. Clair
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:06
CPC Classifications
C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1067; C08G73/1071; C08G73/1057; C08G73/1064
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
13 words
A crystalline polyimide formed as the reaction product of 4,4'-bis-(3,4-dicarboxyphenoxy)diphenylsulfide dianhydride and p-phenylenediamine.
Claim 2
Dependent Claim
13 words
A crystalline polyimide formed as the reaction product of 4,4'-bis-(3,4-dicarboxyphenoxy)diphenylsulfide dianhydride and p-phenylenediamine.
Claim 3
Dependent Claim
13 words
A crystalline polyimide formed as the reaction product of 4,4'-bis-(3,4-dicarboxyphenoxy)diphenylsulfide dianhydride and benzidine.
Claim 4
Dependent Claim
13 words
A crystalline polyimide formed as the reaction product of 4,4'-bis-(3,4-dicarboxyphenoxy)diphenylsulfide dianhydride and benzidine.
Claim 5
Independent Claim
23 words
A method of making a crystalline polyimide by reacting 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfide dianhydride with a diamine selected from the group consisting of p-phenylenediamine and benzidine.
Claim 6
Independent Claim
23 words
A method of making a crystalline polyimide by reacting 4,4'-bis(3,4-dicarboxyphenoxy)diphenylsulfide dianhydride with a diamine selected from the group consisting of p-phenylenediamine and benzidine.
Claim 7
Dependent Claim
73 words
A method of making a crystalline polyimide as in claim 3 wherein the diamine is dissolved in the solvent dimethylacetamide prior to being combined with the dianhydride and the resulting mixture is heated to approximately 40° C. to evaporate the solvent and cyclized by heating to and maintaining the temperature thereof at 100° C. for one hour, at 200° C. for the next one hour, and at 300° C. for the third hour.
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) | 1982-12-24 | 1983-06-25 | 1983-12-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-12-24 | 1987-06-25 | 1987-12-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-12-24 | 1991-06-25 | 1991-12-25 | $7700.00 | Window Closed / Lapsed |