Rheological and drag reduction characteristics of xanthan gum solutions |
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Authors: | H -W Bewersdorff R P Singh |
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Institution: | (1) Fachbereich Chemietechnik, Universität Dortmund, Postfach 500500, D-4600 Dortmund 50, BRD;(2) Materials Science Centre, Indian Institute of Technology, 721302 Kharagpur, India |
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Abstract: | The rheological and turbulent drag reducing characteristics of commercial and purified xanthan gum solutions of concentrations 50–500 ppm have been studied with and without addition of 100 ppm NaCl. The purification by soxlet extraction of xanthan gum using 95% ethanol is effective in removing low-molecular-weight impurities from xanthan. The increased content of higher molecular-weight xanthan in purified xanthan is evident from rheological and drag reduction behavior. The addition of 100 ppm salt to dilute solutions introduces semi-flexibility in xanthan gum solution without occurrence of self-association. The change in molecular behavior in the presence of salt is evident from rheological normal-stress and turbulent drag reduction behaviors. |
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Keywords: | Shearviscosity firstnormal-stress difference drag reduction semi-flexibility self-association xanthan gum solution |
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