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Magazine articles
What is the future for key pulp grades?, Solutions!, December 2003, Vol. 86(12) (65KB)
What is the future for key pulp grades?, Solutions!, December 2003, Vol. 86(12) (65KB)
Magazine articles
Wait till this year?, Solutions!, February 2003, Vol. 86(2) (78KB)
Wait till this year?, Solutions!, February 2003, Vol. 86(2) (78KB)
Magazine articles
The sun shines on Sonoco, Solutions!, February 2003, Vol. 86(2) (71KB)
The sun shines on Sonoco, Solutions!, February 2003, Vol. 86(2) (71KB)
Magazine articles
Forest products industry builds a sustainable record, Solutions!, February 2003, Vol. 86(2) (68KB)
Forest products industry builds a sustainable record, Solutions!, February 2003, Vol. 86(2) (68KB)
Magazine articles
People on the move, Solutions!, February 2003, Vol. 86(2) (119KB)
People on the move, Solutions!, February 2003, Vol. 86(2) (119KB)
Magazine articles
Jefferson smurfit sets its sights on a new future, Solutions!, February 2003, Vol. 86(2) (210KB)
Jefferson smurfit sets its sights on a new future, Solutions!, February 2003, Vol. 86(2) (210KB)
Magazine articles
2001 TAPPI salary survey, Solutions!, February 2003, Vol. 86(2) (347KB)
2001 TAPPI salary survey, Solutions!, February 2003, Vol. 86(2) (347KB)
Magazine articles
Things are warming up, Solutions!, February 2003, Vol. 86(2) (105KB)
Things are warming up, Solutions!, February 2003, Vol. 86(2) (105KB)
Journal articles
Magazine articles
Flow rheology of light foams generated from aqueous solutions of polyvinyl alcohol, TAPPI Journal January 2023
ABSTRACT: Recent studies have shown that foam-assisted application of additives into a wet web has advantages over the conventional way of adding the chemicals into the pulp suspension before forming, e.g., increased mechanical retention as well as high dosage giving increased wet strength without impairing the sheet uniformity. To engineer processes utilizing this new technology, the complex flow behavior of applied foams must be quantified. At the minimum, the foam viscosity and the slip velocity at the solid surfaces need to be known to build practical models that can be used in analyzing and upscaling unit processes of the foam-assisted application.In this study, the rheological behavior was quantified for foams having polyvinyl alcohol (PVOH), a widely used strength additive chemical, as the surfactant. The foam density was varied between 100 g/L and 300 g/L, and the concentration of the PVOH solution was varied between 0.5% and 6.0% (w/w). The foams were generated with a commercial foam generator, and the rheological properties of the foams were measured by using a horizontal pipe bank. At the outlet from the generator, the volumetric flow rate, the absolute pressure, and the bubble size distribution of the foam were measured. In the measurement pipe section, the viscous pressure gradient and the slip velocity were measured, after which the foam was discharged to ambient air pressure. The viscosity and the dynamic surface tension of the PVOH solutions were quantified with commercial laboratory devices. In the viscosity analysis, the apparent shear rate was calculated from the volumetric flow rate, and the resulting apparent viscosity was translated to real material viscosity data by applying the Weissenberg-Rabinowitsch correction. The results indicated that PVOH foams can be described with high accuracy as shear-thinning power-law fluids where the detailed behavior depends on the foam density and the PVOH concentration. Slip flow, as usual, increased with increasing wall shear stress, but it was also dependent on the PVOH concentration, the air content, and the bubble size. For both the foam viscosity and the slip flow, a correlation was found that described the quantitative behavior of all the studied foams with good accuracy.
Magazine articles
SPOTLIGHT: Why Are You Holding Those Fibers?, Solutions!, September 2005, Vol. 88(9)
SPOTLIGHT: Why Are You Holding Those Fibers?, Solutions!, September 2005, Vol. 88(9)