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Journal articles
Open Access
Water-based coatings: problems and solutions, TAPPI JOURNAL July 1988

Water-based coatings: problems and solutions, TAPPI JOURNAL July 1988

Journal articles
Magazine articles
Open Access
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.

Journal articles
Open Access
Investigations of the flocculation behavior of microparticle retention systems,TAPPI JOURNAL & Solutions! December 2004

Investigations of the flocculation behavior of microparticle retention systems,TAPPI JOURNAL & Solutions! December 2004

Journal articles
Open Access
Preparation of specialized paper, Solutions! & TAPPI JOURNAL, April 2004 (349KB)

Preparation of specialized paper, Solutions! & TAPPI JOURNAL, April 2004 (349KB)

Journal articles
Open Access
Metals buildup in TCF bleach plant closure: laboratory simulation, SOLUTIONS! & TAPPI JOURNAL, May 2002 (208KB)

Metals buildup in TCF bleach plant closure: laboratory simulation, SOLUTIONS! & TAPPI JOURNAL, May 2002 (208KB)

Magazine articles
Open Access
Forklift emissions - some solutions, TAPPI JOURNAL, December 1993, Vol. 76(12)

Forklift emissions - some solutions, TAPPI JOURNAL, December 1993, Vol. 76(12)

Journal articles
Open Access
Performance of cationic styrene maleimide copolymers in the wet end of papermaking, Solutions! & TAPPI JOURNAL, April 2004 (198KB)

Performance of cationic styrene maleimide copolymers in the wet end of papermaking, Solutions! & TAPPI JOURNAL, April 2004 (198KB)

Journal articles
Open Access
Fiber-to-fiberâ??a case study at Domtar, Cornwall, Solutions! & TAPPI JOURNAL, March 2004, Vol. 3(3) (171KB)

Fiber-to-fiber—a case study at Domtar, Cornwall, Solutions! & TAPPI JOURNAL, March 2004, Vol. 3(3) (171KB)

Journal articles
Open Access
Response of bagasse and wheat straw recycled pulps to refining, Solutions! & TAPPI JOURNAL, October 2004, Vol. 3(10) (349KB)

Response of bagasse and wheat straw recycled pulps to refining, Solutions! & TAPPI JOURNAL, October 2004, Vol. 3(10) (349KB)

Journal articles
Open Access
Paper structure and printability as controlled by the fibrous elements, Solutions! & TAPPI JOURNAL, June 2004, Vol. 3(6) (528KB)

Paper structure and printability as controlled by the fibrous elements, Solutions! & TAPPI JOURNAL, June 2004, Vol. 3(6) (528KB)

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