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TURBIDITY FRACTIONATION ANALYSIS METHOD AND APPARATUS

IP.com Disclosure Number: IPCOM000022646D
Publication Date: 2004-Mar-22
Document File: 3 page(s) / 47K

Publishing Venue

The IP.com Prior Art Database

Abstract

Turbidity Fractionation Analysis ("TFA") refers to an analytical instrument and method which fractionates and analyzes the weight percent of polymer which has been fractionated. The instrument fractionates polymers based on chemical composition in a manner similar to the known methods called ATREF and CRYSTAF. Referring to Figure 1, the TFA instrument comprises a laser, an intensity detector, and a cell holder that is capable of controlled heating and cooling. The instrument monitors the turbidity of a polymer solution with changes in temperature. The data produced from TFA is similar to the data produced by an ATREF if the experiment is performed in heating mode, or it is similar to the data produced by a CRYSTAF if the experiment is performed in cool down mode. As can be seen, the TFA instrument is much simpler and thus less expensive than a commercial CRYSTAF instrument or a typical ATREF instrument. The key to the invention is that TFA monitors the changes in turbidity of a polymer solution as it relates to the polymer's short chain branching distribution and crystallization behavior. The analysis can be carried out in a variety of solvents. The instrument has applications for analysis of polymer crystallization, precipitation and dissolution relating to measurement of chemical composition distribution and crystallization kinetics. With the inclusion of the scattering responses of the polymer solution, the invention also can be used to estimate the molecular weight of the polymer in solution and its fractions. Applications have been identified for standard laboratory analysis, high throughput measurement, and online measurement.

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TURBIDITY FRACTIONATION ANALYSIS

METHOD AND APPARATUS

Turbidity Fractionation Analysis (“TFA”) refers to an analytical instrument and method which fractionates and analyzes the weight percent of polymer which has been fractionated.  The instrument fractionates polymers based on chemical composition in a manner similar to the known methods called ATREF and CRYSTAF.

Referring to Figure 1, the TFA instrument comprises a laser, an intensity detector, and a cell holder that is capable of controlled heating and cooling.  The instrument monitors the turbidity of a polymer solution with changes in temperature.  The data produced from TFA is similar to the data produced by an ATREF if the experiment is performed in heating mode, or it is similar to the data produced by a CRYSTAF if the experiment is performed in cool down mode.  As can be seen, the TFA instrument is much simpler and thus less expensive than a commercial CRYSTAF instrument or a typical ATREF instrument.

The key to the invention is that TFA measures the changes in turbidity of a polymer solution as it relates to the polymer’s short chain branching distribution and crystallization behavior.  The analysis can also be carried out in a variety of solvents.  The instrument has applications for analysis of polymer crystallization, precipitation and dissolution relating to measurement of chemical composition distribution and crystallization kinetics.

With the inclusion of the scattering responses of the polymer solution, the invention also can be used to estimate the molecular weight of the polymer in solution and its fractions.

Applications have been identified for standard laboratory analysis, high throughput measurement, and online measurement.

Example

This example involves applying TFA to measure the short chain branching distribution of a semi-crystalline polymer.  The TFA instrument setup shown in Figure 1 is used for this measurement.   A linear low density polyethylene sample of ethylene/1-octene copolymer having a melt index 1.0, density 0.92, Mw/Mn 4.3 is dissolved at a concentration of 1 mg/mL in 1,2,4 trichlorobenzene, and is cooled from 130°C to 30°C at a rat...