Patent US4824629A successfully refreshed from Google Patents.
US4824629A
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Process for preparing an oriented crystalline syndiotactic vinylaromatic polymer
Assignee: Dow Chemical Co
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Filing: 1988-02-04
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Granted: 1989-04-25
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Expires: 2008-02-04
Abstract
Abstract Oriented, syndiotactic, optically transparent vinylaromatic polymers are prepared by a process comprising heating the polymer to a temperature above its crystalline melting point, cooling the polymer to a temperature less than an orientable temperature at a rate sufficient to avoid substantial crystal formation, and inducing strain into the polymer while at a orientable temperature to induce crystal formation and molecular orientation.
Inventors
- 👤 Jerry T. Seitz
- 👤 Charles A. Berglund
- 👤 Andrew J. Pasztor, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:02
CPC Classifications
B; B29; B29C; B29C55/00; B29C55/005; B29K; B29K2025/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
93 words
A process for preparing an oriented, crystalline, syndiotactic vinylaromatic polymer comprising: (1) heating a syndiotactic vinylaromatic polymer to a temperature above the crystalline melting point; (2) cooling the syndiotactic vinylaromatic polymer to a temperature less than an orientable temperature at a rate of cooling sufficient to result in a cooled polymer that is substantially amorphous; (3) heating the syndiotactic vinylaromatic polymer to an orientable temperature; (4) imparting sufficient strain into the vinylaromatic polymer in one or more directions to produce molecular orientation and crystal formation; and (5) recovering the oriented, syndiotactic, vinylaromatic polymer.
Claim 2
Dependent Claim
93 words
A process for preparing an oriented, crystalline, syndiotactic vinylaromatic polymer comprising: (1) heating a syndiotactic vinylaromatic polymer to a temperature above the crystalline melting point; (2) cooling the syndiotactic vinylaromatic polymer to a temperature less than an orientable temperature at a rate of cooling sufficient to result in a cooled polymer that is substantially amorphous; (3) heating the syndiotactic vinylaromatic polymer to an orientable temperature; (4) imparting sufficient strain into the vinylaromatic polymer in one or more directions to produce molecular orientation and crystal formation; and (5) recovering the oriented, syndiotactic, vinylaromatic polymer.
Claim 3
Dependent Claim
12 words
A process according to claim 1 wherein the polymer is syndiotactic polystyrene.
Claim 4
Dependent Claim
23 words
A process according to claim 1 wherein the polymer is cooled while under a pressure of at least about 1000 lb/in 2 .
Claim 5
Dependent Claim
22 words
A process according to claim 2 wherein the polymer is heated in step 1) to a temperature of greater than 280° C.
Claim 6
Dependent Claim
21 words
A process according to claim 2 wherein the polymer is cooled in step 2) to a temperature less than 100° C.
Claim 7
Dependent Claim
21 words
A process according to claim 1 wherein the polymer is cooled in step 2) at a cooling rate of 50° C./sec.
Claim 8
Dependent Claim
26 words
A process according to claim 1 wherein the amount of strain imparted to the polymer is sufficient to provide an extension ratio of at least 3.
Claim 9
Dependent Claim
33 words
A process according to claim 1 wherein the amount of strain imparted to the polymer is sufficient to produce a degree of crystallinity equal to or greater than the degree of normal crystallinity.
Claim 10
Dependent Claim
23 words
A process according to claim 1 wherein the degree of crystallinity of the oriented crystalline syndiotactic vinylaromatic polymer is greater than 40 percent.
References Cited (Backward Citations)
US3069406A
Cited
US4692295A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-04-24 | 1992-10-24 | 1993-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-24 | 1996-10-24 | 1997-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-24 | 2000-10-24 | 2001-04-25 | $7700.00 | Window Closed / Lapsed |