SEC–viscometer detector systems. I. Calibration and determination of mark–houwink constants

Autor: R. Lew, Stephen T. Balke, P. Cheung, T. H. Mourey
Rok vydání: 1993
Předmět:
Zdroj: Journal of Applied Polymer Science. 47:1685-1700
ISSN: 1097-4628
0021-8995
DOI: 10.1002/app.1993.070470916
Popis: Five different types of calibration curve currently used in size exclusion chromatography-differential viscometer (SEC–DV) systems were identified and their use summarized. A simple method of deriving weighting factors for fitting local intrinsic viscosity calibration curves was shown to greatly improve the precision of calculated molecular weight distributions. The problem of reliably extrapolating the fitted curves to allow for differences in sensitivity among detectors has yet to be examined. With regard to Mark—Houwink constants, a method of fitting data from the SEC–DV system to obtain more statistically sound values was derived. For the data used here, the new method involves fitting a plot of logarithm of the local intrinsic viscosity of the sample vs. logarithm of the universal calibration curve parameter, Ji. Results for the data obtained appeared only slightly more precise than those for the traditional method. However, the new method promises improved reliability. © 1993 John Wiley & Sons, Inc.
Databáze: OpenAIRE
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