[article]
| Titre : |
Capillary forces in wet paper |
| Type de document : |
texte imprimé |
| Auteurs : |
Theo G.M. Van de Ven, Auteur |
| Année de publication : |
2008 |
| Article en page(s) : |
p. 7250–7256 |
| Note générale : |
Chemical engineering |
| Langues : |
Anglais (eng) |
| Mots-clés : |
Wet paper Capillary forces Static friction |
| Résumé : |
An analysis of capillary forces in wet paper and between two wet sheets leads to a number of interesting conclusions. Experimentally, it is found that the (static) friction force between two rewetted sheets is a maximum (4.8 kN/m2) at a solids content of 38%, at which the air−water surface area is estimated to be a maximum. Assuming that, at this concentration, all of the water between fibers is in liquid bridges between fiber crossings, theory predicts a friction force of similar magnitude. Making the same assumptions in predicting the strength of wet sheets leads to a theoretical prediction that is an order of magnitude smaller than the observed tensile strength. Contrary to theoretical predictions for smooth spheres or cylinders, the Laplace forces decrease to zero when the water content between the fibers goes to zero, at the fiber saturation point. This is likely caused by the surface roughness of the fibers. It can be concluded that the Laplace pressure is unimportant in determining the strength of wet paper, contrary to the assumptions of previous studies. The observations that the wet web strength increases with decreasing capillary forces and that the wet strength is smaller than predicted by capillary theory confirm that the wet web strength is not determined by capillary forces alone, but must involve an additional mechanism, likely to be an entanglement friction. |
| En ligne : |
http://pubs.acs.org/doi/abs/10.1021/ie800423r |
in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7250–7256
[article] Capillary forces in wet paper [texte imprimé] / Theo G.M. Van de Ven, Auteur . - 2008 . - p. 7250–7256. Chemical engineering Langues : Anglais ( eng) in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7250–7256
| Mots-clés : |
Wet paper Capillary forces Static friction |
| Résumé : |
An analysis of capillary forces in wet paper and between two wet sheets leads to a number of interesting conclusions. Experimentally, it is found that the (static) friction force between two rewetted sheets is a maximum (4.8 kN/m2) at a solids content of 38%, at which the air−water surface area is estimated to be a maximum. Assuming that, at this concentration, all of the water between fibers is in liquid bridges between fiber crossings, theory predicts a friction force of similar magnitude. Making the same assumptions in predicting the strength of wet sheets leads to a theoretical prediction that is an order of magnitude smaller than the observed tensile strength. Contrary to theoretical predictions for smooth spheres or cylinders, the Laplace forces decrease to zero when the water content between the fibers goes to zero, at the fiber saturation point. This is likely caused by the surface roughness of the fibers. It can be concluded that the Laplace pressure is unimportant in determining the strength of wet paper, contrary to the assumptions of previous studies. The observations that the wet web strength increases with decreasing capillary forces and that the wet strength is smaller than predicted by capillary theory confirm that the wet web strength is not determined by capillary forces alone, but must involve an additional mechanism, likely to be an entanglement friction. |
| En ligne : |
http://pubs.acs.org/doi/abs/10.1021/ie800423r |
|
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