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Water vapour absorption by full chrome leather / R. G. Mitton in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 54, N° 7 (07/1970)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 54, N° 7 (07/1970) . - p. 248-266 Titre : Water vapour absorption by full chrome leather Type de document : texte imprimé Auteurs : R. G. Mitton, Auteur Année de publication : 1970 Article en page(s) : p. 248-266 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Absorption Cuir Humidité -- Absorption Hystérésis L'hystérésis (ou hystérèse) et signifiant "après" ou "plus tard", est la propriété d'un système qui tend à demeurer dans un certain état quand la cause extérieure qui a produit le changement d'état a cessé. Vapeur d'eau Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Absorption and desorption isotherms for water vapour in full chrome leather at 5, 20 and 35°c are given. They agree satisfactorily with those previously found by the author and by Kanagy, but uptakes are higher than obtained by most other investigators, probably because they allowed insufficient time for complete equilibrium. The moisture content at 65% r.h. is far higher than usually assumed in leather analysis. At high humidities, regains exceed 70 %. Although the outline of the hysteresis cycle was measured by slow approach to equilibrium (years), this period was only necessary because of slow diffusion of moisture through air; the equilibrium values obtained by rapid equilibration in a vacuum are little different. At humidities up to about 60%, the shape of the ascending humidity isotherm is different if the specimens are heated to 100°c beforehand. The descending branch is little changed. The usual hysteresis cycle defines an area which is crossed by isotherms descending from points on the rising boundary curve, or ascending from points on the descending boundary curve. A number of these isotherms are shown. Data are given for absorption and desorption at 20°c, 65 % r.h. of leathers with different chrome contents. The width of the hysteresis cycle under these conditions increases with chrome content, probably because crosslinking by chromium reduces swelling during absorption, and reduces shrinking during desorption. Note de contenu : - Leathers used for the experiments - Measurements of dry weights - Method of conditioning - Times to reach equilibrium - The hysteresis loop - The hysteresis loop for chrome leather dried without heating - The hysteresis loop for chrome leather dired at 105°C - States within the boundary hysterisis loop - Absorption and desorption at other temperatures - Application of the brunauer, Emmett and Teller equation - TABLE 1 : Values estimated from the B.E.T. equation for ascending and descending isotherms En ligne : https://drive.google.com/file/d/1jvvQhHqMDmm-ON4XBuVrqOcWHHNNKhLO/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37017 [article]

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