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Capillary forces in wet paper / Theo G.M. Van de Ven in Industrial & engineering chemistry research, Vol. 47 N°19 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°19 (Octobre 2008) . - p. 7250–7256 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 [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

Why does paper get stronger as it dries? / Alvaro Tejado in Materials today, Vol. 13 N° 9 (Septembre 2010) 

Public ISBD [article]  in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 42–49 Titre : Why does paper get stronger as it dries? Type de document : texte imprimé Auteurs : Alvaro Tejado, Auteur ; Theo G.M. Van de Ven, Auteur Année de publication : 2011 Article en page(s) : pp. 42–49 Note générale : Ingénierie Langues : Anglais (eng) Mots-clés : Paper  Wet  paper  Fiber  Friction  Capillary  forces Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : Surprisingly the strength of wet paper is still poorly understood. Here we show that the traditional explanation of the strength of wet paper is incorrect. Observations that the capillary force in fiber crossings in wet paper approaches zero as the water is evaporated show that they are not responsible for the strength of wet paper. Instead we present evidence that fiber entanglements and friction are the cause. Like paper, films made of nanotubes, nanorods, nanofibers or nanoribbons also consist of randomly oriented fibers, and this field may well benefit from an increased knowledge of paper properties. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701644 [article] Why does paper get stronger as it dries? [texte imprimé] / Alvaro Tejado, Auteur ; Theo G.M. Van de Ven, Auteur . - 2011 . - pp. 42–49. Ingénierie Langues : Anglais (eng) in Materials today > Vol. 13 N° 9 (Septembre 2010) . - pp. 42–49 Mots-clés : Paper  Wet  paper  Fiber  Friction  Capillary  forces Index. décimale : 620 Essais des matériaux. Matériaux commerciaux. Station génératrice d'énergie. Economie de l'énergie Résumé : Surprisingly the strength of wet paper is still poorly understood. Here we show that the traditional explanation of the strength of wet paper is incorrect. Observations that the capillary force in fiber crossings in wet paper approaches zero as the water is evaporated show that they are not responsible for the strength of wet paper. Instead we present evidence that fiber entanglements and friction are the cause. Like paper, films made of nanotubes, nanorods, nanofibers or nanoribbons also consist of randomly oriented fibers, and this field may well benefit from an increased knowledge of paper properties. DEWEY : 620 ISSN : 1369-7021 En ligne : http://www.sciencedirect.com/science/article/pii/S1369702110701644