US3837217A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Measurement of polymer molecular weight distribution
Assignee: ExxonMobil Technology and Engineering Co
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Filing: 1972-10-19
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Granted: 1974-09-24
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Expires: 1992-10-19
Abstract
Abstract For use with a gel permeation chromatograph measuring molecular weight distribution of polymeric materials, the combination of a piezoelectric crystal detector for measuring mass with an automatic viscometer for inferential measurement of molecular weight provides improved measurement of absolute molecular weight distribution of polymeric materials. Recycling of polymer fractions through the gel permeation chromatograph provides improved resolution of the individual fractions.
Inventors
- 👤 W Schulz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 10:48
CPC Classifications
G; G01; G01N; G01N30/00; G01N30/02; G01N30/26; G01N30/38; G01N30/44; G01N11/00; G01N11/02; G01N11/04; G01N11/06; G01N30/62; G01N30/78
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
315 words
A method of determining the absolute molecular weight distribution of polymeric materials as they are eluted from a gel permeation chromatographic column by a solvent comprising the following steps: a. dividing the eluted volume into uniform portions; b. sampling each of said uniform portions at a plurality of uniformly spaced time intervals and measuring the mass of the polymer in each sample by, 1. depositing each sample on the surface of a piezoelectric crystal; 2. evaporating the solvent from each sample; 3. measuring the mass of the polymer remaining after the solvent has been evaporated in step (2) by the change in the vibrating frequency of said crystal; c. determining from (b) the relationship between mass and volume eluted for each of said portions of (a); d. selecting as the elution volume representative of each portion the volume corresponding to the peak mass determined in (c) foR said portion; e. determining the concentration of said polymer in each of said portions by combining the mass of step (b) with the volume of step (a); f. measuring the time for each of said portions to pass through a capillary viscometer; g. determining the intrinsic viscosity of each of said portions as proportional to the ratio of the time of (f) to the time for an equal volume of pure solvent to pass through said viscometer; h. determining from a previously measured universal correlation of elution volume versus the product of intrinsic viscosity and molecular weight the said product for each of said portions using the elution volume selected in (d); i. determining the molecular weight of the polymer in each of said portions by dividing the product of step (h) by the intrinsic viscosity of step (g); and j. combining for each of said portions the molecular weight of step (i) with the mass of step (b) to obtain the molecular weight distribution of said polymer.
Claim 2
Independent Claim
315 words
A method of determining the absolute molecular weight distribution of polymeric materials as they are eluted from a gel permeation chromatographic column by a solvent comprising the following steps: a. dividing the eluted volume into uniform portions; b. sampling each of said uniform portions at a plurality of uniformly spaced time intervals and measuring the mass of the polymer in each sample by, 1. depositing each sample on the surface of a piezoelectric crystal; 2. evaporating the solvent from each sample; 3. measuring the mass of the polymer remaining after the solvent has been evaporated in step (2) by the change in the vibrating frequency of said crystal; c. determining from (b) the relationship between mass and volume eluted for each of said portions of (a); d. selecting as the elution volume representative of each portion the volume corresponding to the peak mass determined in (c) foR said portion; e. determining the concentration of said polymer in each of said portions by combining the mass of step (b) with the volume of step (a); f. measuring the time for each of said portions to pass through a capillary viscometer; g. determining the intrinsic viscosity of each of said portions as proportional to the ratio of the time of (f) to the time for an equal volume of pure solvent to pass through said viscometer; h. determining from a previously measured universal correlation of elution volume versus the product of intrinsic viscosity and molecular weight the said product for each of said portions using the elution volume selected in (d); i. determining the molecular weight of the polymer in each of said portions by dividing the product of step (h) by the intrinsic viscosity of step (g); and j. combining for each of said portions the molecular weight of step (i) with the mass of step (b) to obtain the molecular weight distribution of said polymer.
Claim 3
Dependent Claim
6 words
evaporating the solvent from each sample;
Claim 4
Dependent Claim
6 words
evaporating the solvent from each sample;
Claim 5
Dependent Claim
37 words
The method of claim 1 wherein each portion of eluted polymer leaving step (f) is recycled to the chromatographic column, thereby improving the separation of the polymer by molecular weight and improving the accuracy of step 1(d).
Claim 6
Independent Claim
112 words
An apparatus for determining the molecular weight distribution of polymeric materials as they are eluted from a gel permeation chromatographic column by a solvent comprising: a. a calibrated syphon for dividing said eluted polymer into uniform portions; b. comparative viscometer means for measuring the viscosity of each of said portions passing through said viscometer and the viscosity of pure solvent; c. mass measuring means for determining the mass of polymer contained in each of said portions and the concentration thereof; and d. means for calculating the molecular weight of the polymer in each of said portions using a universal curve of elution volume versus the product of intrinsic viscosity and molecular weight.
Claim 7
Independent Claim
112 words
An apparatus for determining the molecular weight distribution of polymeric materials as they are eluted from a gel permeation chromatographic column by a solvent comprising: a. a calibrated syphon for dividing said eluted polymer into uniform portions; b. comparative viscometer means for measuring the viscosity of each of said portions passing through said viscometer and the viscosity of pure solvent; c. mass measuring means for determining the mass of polymer contained in each of said portions and the concentration thereof; and d. means for calculating the molecular weight of the polymer in each of said portions using a universal curve of elution volume versus the product of intrinsic viscosity and molecular weight.
Claim 8
Dependent Claim
233 words
measuring the mass of the polymer remaining after the solvent has been evaporated in step (2) by the change in the vibrating frequency of said crystal; c. determining from (b) the relationship between mass and volume eluted for each of said portions of (a); d. selecting as the elution volume representative of each portion the volume corresponding to the peak mass determined in (c) foR said portion; e. determining the concentration of said polymer in each of said portions by combining the mass of step (b) with the volume of step (a); f. measuring the time for each of said portions to pass through a capillary viscometer; g. determining the intrinsic viscosity of each of said portions as proportional to the ratio of the time of (f) to the time for an equal volume of pure solvent to pass through said viscometer; h. determining from a previously measured universal correlation of elution volume versus the product of intrinsic viscosity and molecular weight the said product for each of said portions using the elution volume selected in (d); i. determining the molecular weight of the polymer in each of said portions by dividing the product of step (h) by the intrinsic viscosity of step (g); and j. combining for each of said portions the molecular weight of step (i) with the mass of step (b) to obtain the molecular weight distribution of said polymer.
Claim 9
Dependent Claim
233 words
measuring the mass of the polymer remaining after the solvent has been evaporated in step (2) by the change in the vibrating frequency of said crystal; c. determining from (b) the relationship between mass and volume eluted for each of said portions of (a); d. selecting as the elution volume representative of each portion the volume corresponding to the peak mass determined in (c) foR said portion; e. determining the concentration of said polymer in each of said portions by combining the mass of step (b) with the volume of step (a); f. measuring the time for each of said portions to pass through a capillary viscometer; g. determining the intrinsic viscosity of each of said portions as proportional to the ratio of the time of (f) to the time for an equal volume of pure solvent to pass through said viscometer; h. determining from a previously measured universal correlation of elution volume versus the product of intrinsic viscosity and molecular weight the said product for each of said portions using the elution volume selected in (d); i. determining the molecular weight of the polymer in each of said portions by dividing the product of step (h) by the intrinsic viscosity of step (g); and j. combining for each of said portions the molecular weight of step (i) with the mass of step (b) to obtain the molecular weight distribution of said polymer.
Claim 10
Dependent Claim
17 words
The apparatus of claim 3 further comprising means for calculating the molecular weight distribution of said polymer.
Claim 11
Dependent Claim
31 words
The apparatus of claim 3 further comprising means for recycling the uniform portions of (a) to the gel chromatographic column after the viscosity is measured by the viscometer means of (b).
Claim 12
Dependent Claim
39 words
The apparatus of claim 3 wherein said mass measuring means comprises a piezoelectric crystal whereby mass is determined by the change in vibrating frequency of said crystal after a sample has been placed thereon and the solvent evaporated therefrom.
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) | 1977-09-23 | 1978-03-25 | 1978-09-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-23 | 1982-03-25 | 1982-09-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-23 | 1986-03-25 | 1986-09-24 | $7700.00 | Window Closed / Lapsed |