Viscoelastic properties of high solids softwood kraft black liquors

Journal Article · Sun Jan 01 04:00:00 EST 1995 · Industrial and Engineering Chemistry Research; (United States)

DOI:https://doi.org/10.1021/ie00040a042· OSTI ID:6565255

Zaman, A A; Fricke, A L ^[1]

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1. Univ. of Florida, Gainesville, FL (United States). Dept. of Chemical Engineering

The linear viscoelastic functions of several softwood slash pine kraft black liquors from a two level, four variable factorially designed pulping experiment were determined for solids concentrations from 65% to 81% and temperatures from 40 to 85 C. At high solids and lower temperatures, black liquors behave like un-cross-linked polymers.The exact level of dynamic viscosity and storage modulus at any given condition is dependent upon the solids composition which will vary from liquor to liquor. The linear viscoelastic functions were described using Cross and Carreau-Yasuda models. Superposition principles developed for polymer melts and concentrated polymer solutions were applied to obtain reduced correlations for dynamic viscosity and storage modulus. The data for dynamic viscosity were shifted over the whole range of temperature, solids concentrations, and frequency, and a single curve for dynamic viscosity behavior of every liquor was obtained. The data for storage modulus did not superimpose into a single curve for the effects of solids concentration. The reduced correlations were used to estimate the viscoelasticity of the liquors near normal firing conditions and found that black liquors will not have any problem in droplet formation for concentrations up to 81% solids and temperatures above 120 C. The viscometric and linear viscoelastic functions of black liquors were compared (Cox-Merz rule), and it was shown that at sufficiently low shear rates and frequencies both shear viscosity and the magnitude of the complex viscosity approach zero shear rate viscosity.

• DOE Contract Number: FG02-85CE40740
• OSTI ID: 6565255
• Journal Information: Industrial and Engineering Chemistry Research; (United States), Journal Name: Industrial and Engineering Chemistry Research; (United States) Vol. 34:1; ISSN IECRED; ISSN 0888-5885
• Country of Publication: United States
• Language: English

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