Investigation into the controlled drying of sheepskins / J. R. Yates in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXI (Année 1966)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXI (Année 1966) . - p. 235-256 Titre : Investigation into the controlled drying of sheepskins : II. Effect of drying conditions on various properties of the skins Type de document : texte imprimé Auteurs : J. R. Yates, Auteur Année de publication : 1966 Article en page(s) : p. 235-256 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Analyse de variance En statistique, l'analyse de la variance (terme souvent abrégé par le terme anglais ANOVA : ANalysis Of VAriance) est un ensemble de modèles statistiques utilisés pour vérifier si les moyennes des groupes proviennent d'une même population. Les groupes correspondent aux modalités d'une variable qualitative (p. ex. variable : traitement; modalités : programme d'entrainement sportif, suppléments alimentaires ; placebo) et les moyennes sont calculés à partir d'une variable continue (p. ex. gain musculaire). Ce test s'applique lorsque l'on mesure une ou plusieurs variables explicatives catégorielles (appelées alors facteurs de variabilité, leurs différentes modalités étant parfois appelées "niveaux") qui ont de l'influence sur la loi d'une variable continue à expliquer. On parle d'analyse à un facteur lorsque l'analyse porte sur un modèle décrit par un seul facteur de variabilité, d'analyse à deux facteurs ou d'analyse multifactorielle sinon. (Wikipedia) Centrifugation Cuirs et peaux -- Séchage Cuirs et peaux de moutons Peau -- Histologie Peaux brutes -- Teneur en eau Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The equilibrium water content (e.w.c.) of sheepskins has been estab-lished over a humidity range of 20-90 percent at 20°C., 35°C. and 50°C. Increase of temperature gives a slight decrease in e.w.c. for a given relative humidity. There is a well defined hysteresis effect as indicated by the e.w.c. values obtained in absorption and desorption. There are differences in the e.w.c. values obtained with samples from similar positions on different skins, and even between different sampling positions within a skin, for equilibration under a given set of conditions. Up to 70 percent of the water held in a sheepskin can be removed by centrifugation, indicating that this water is not very tightly bound. Sheepskins were dried in air currents at room temperature at 30°C., 40°C. and 50°C., by freeze drying, vacuum drying at 1°C., and by acetone dehydration. The skins dried by the latter three methods give, after re-soaking, a skin which most closely resembles a green skin, as judged by water uptake and histological appearance. None of the drying methods tested affects the time taken for wool loosening to occur in the "Sweating" process. Note de contenu : - MATERIALS - METHODS : Effect of controlled humidity on the equilibrium water content (E.W.C.) of the skin - Determination of the water expressible from sheepskins by centrifugation - Drying - Histological examination of sheepskins dried in different ways - Effect of method of drying on the rate of "sweating" (wool loosening) - RESULTS AND DISCUSSION : Effect of drying and equilibrating at conditions of controlled relative humidity - Determination of the expressible water from sheepskins - Histological investigation of skins dried in the various ways - Effect of method of drying on water uptake properties - Effect of method of drying on water uptake - Table 1 : Equilibrium water contents (% D.W.B.) of sheepskin - Table 2 : E.W.C. values (% D.W.B.) for P2 and P5 for saturation humidities - Table 3 : E.W.C. values for P1-P5 on a particular skin - Table 4 : Range and mean of E.W.C. values for skin samples - Table 5 : E.W.C. values after repeated re-equilibrium in the conditioning chamber at 100°F - Table 6 : Analysis of variance and treatment means for the thickness treatment means for the thickness measurements on the skin after soaking - Table 7 : Drying X temperature interaction means for water uptake (MG) per standard sample - Table 8 : Drying X treatment interaction means for water uptake (MG) per standard sample over the complete uptake period 0-3 days - Table 9 : Drying X solutioninteractionmeans for water uptake (MG) per standard sample - Table 10 : Swelling means for the drying W soaking treatment - Table 11 : Means for dry thickness for the skin sample (in. X 10-4) - Table 12 : Analyis of variance and drying X soaking interaction means En ligne : https://drive.google.com/file/d/1kxxnpWKQs1P19-ve5-zvMKmbFeHXLrrc/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37942 [article]

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Investigations into the controlled drying of sheepskins / J. R. Yates in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXI (Année 1966)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXI (Année 1966) . - p. 171-188 Titre : Investigations into the controlled drying of sheepskins : I. Establishment of the drying characteristics of the system Type de document : texte imprimé Auteurs : J. R. Yates, Auteur Année de publication : 1966 Article en page(s) : p. 171-188 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuirs et peaux -- Séchage Cuirs et peaux de moutons Peaux brutes -- Teneur en eau Température Température de retrait Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The drying of sheepskins is followed in a commercial drying estab-lishment in order to ascertain what is the acceptable level of water content in a "dry" skin. A water content (dry weight basis) in the range 14-24 percent is acceptable. The time required to reach this level is found to vary tremendously with the prevailing climatic conditions. On a laboratory scale, the influence of temperature on drying rate is investigated, and from the drying rate curves at the different tempera-tures, the "apparent activation energy" of drying is calculated over the range of water contents investigated. The value of this activation energy is of the order of 5-8 Kcals/mole, and does not vary with the water content of the skin down to about ten percent but thereafter shows a marked rise. It is also dependent on the skin thickness. Drying results in a decreased amount of water uptake and an increase in the amount of extractable nitrogen on subsequent soaking, and an increase in the shrinkage temperature of the skin. Note de contenu : - MATERIALS - METHODS : Effect of climatic conditions on the drying process - Effect of temperature on draying rate - Effect of degree of drying on extractable nitrogen - Effect of degree of drying on subsequent water uptake - Measurement of shrinkage temperature at different water contents - RESULTS AND DISCUSSION : Effect of changing climatic conditions on rate of drying - Effect of temperature on rate of drying - Calculation of "apparent activation energy of drying - Effect of degree of drying on subsequent water uptake - Effect of degree of drying on shrinkage temperature - Table 1 : Actual water loss in Mg./Min. for series 2 skin - Table 2 : "Apparent activation energies" of drying at different regain levels - Table 3 : "Apparent activation energies" for low water content - Table 4 : Analysis of variance of skin thickness and water cotent on "apparent activation energy" - Table 5 : Extractable nitrogen in Mg/Gm dry WT. of skin, with the water content (d.w.b.) - Table 6 : Analysis of variance and the industrial regression coefficients for the 15 sets of extractable nitrogen-water content data - Table 7 : Variation of final water content after soaking for 72 hours at 1°C. With the initial water content - Table 8 : Analysis of co-variance for the initial and final water contents of the skin samples, and the Bo coefficients for the six positions En ligne : https://drive.google.com/file/d/1F6jLD8P9e_xXLbLTNjE2NbLGjGdH-d8J/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37941 [article]

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Self-driven directional dehydration enabled eco-friendly manufacture of chrome-free leather / Yawen Huang in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 4 (Année 2022)  

[article]  inJOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 4 (Année 2022) . - 12 p. Titre : Self-driven directional dehydration enabled eco-friendly manufacture of chrome-free leather Type de document : texte imprimé Auteurs : Yawen Huang, Auteur ; Hanzhong Xiao, Auteur ; Haoliang Pu, Auteur ; Ni Xue, Auteur ; Baicun Hao, Auteur ; Xin Huang, Auteur ; Bi Shi, Auteur Année de publication : 2022 Article en page(s) : 12 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Alcool Caractérisation Déshydratation Peaux brutes -- Teneur en eau Tannage chrome free Zéolites Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Manufacture of eco-friendly chrome-free leather is of great significance for realizing sustainable development of leather industry. Conventional tanning theory believes that it is impossible to convert raw hide to leather without the utilization of cross-linking agent (e.g., chrome salts) among collagen fibers in raw hide. Here, we developed a brand-new leather manufacture strategy that relied on the composite dehydration media enabled self-driven directional dehydration mechanism to accomplish chrome-free leather manufacture for the first time, rather than followed the classic cross-linking mechanism that has been obeyed for more than one century in leather industry. We demonstrated that the essence of leather making is to regulate the water content in raw hide rather than to form cross-linkage among collagen fibers. The composite dehydration media comprised of anhydrous ethanol and molecular sieves (3A activated zeolite powder) successfully guaranteed continuous self-driven directional dehydration of raw hide by establishing stable water concentration gradient between raw hide and ethanol, which significantly increased the dispersity of collagen fibers in raw hide (with the water content reduced from 56.07% to 5.20%), thus obtaining chrome-free leather that is more ecological than chrome-tanned leather due to the elimination of any tanning agent. The as-prepared chrome-free leather exhibited outstanding tear force (174.86 N), tensile strength (24.56 N mm−2), elongation at break (53.28%) and dry-thermal stability, superior to chrome-tanned leather. Notably, the used composite dehydration media was recyclable for chrome-free leather manufacture, therefore facilitating an environmentally benign leather manufacture process. Our investigations are expected to open up a new conceptual leather making strategy that is applicable for realizing substantial manufacture of eco-friendly leather. Note de contenu : - Materials - Preparation of eco-friendly chrome-free leather - Dehydration of raw hide using anhydrous ethanol - Preparation of chrome-tanned leather - Selective adsorption of 3A activated zeolite powder to water from the water-ethanol mixture - Characterization DOI : https://doi.org/10.1186/s42825-022-00089-0 En ligne : https://link.springer.com/content/pdf/10.1186/s42825-022-00089-0.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37582 [article]

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