Closed circulator sole leather tannages at ambient temperatures / D. A. Williams-Wynn in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 54, N° 10 (10/1970)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 54, N° 10 (10/1970) . - p. 356-360 Titre : Closed circulator sole leather tannages at ambient temperatures Type de document : texte imprimé Auteurs : D. A. Williams-Wynn, Auteur Année de publication : 1970 Article en page(s) : p. 356-360 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuirs et peaux -- Propriétés physiques Semelles Tannage Température Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : A study has been made of the effect of tanning in the closed circulator system at room temperature, and the results compared with tannages effected at elevated temperature. Tannage is undoubtedly slower at ambient temperature than at 35°C, and it is established that at low temperature a period of at least 24 days, and in some cases more than 48 days is necessary to achieve what is attained in 12 days in a warm circulator system. The results of this experiment emphasise the considerable advantages of the tannage at elevated temperature. Note de contenu : - Table 1 : Analytical results (calculated to 14% moisture) - Table 2a : Physical properties En ligne : https://drive.google.com/file/d/1v8U-p2d-NVSCJPUyZbtaNXf6726_80xY/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37021 [article]

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Consideration of the vegetable tannin chromium-collagen system / D. A. Williams-Wynn in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 54, N° 1 (01/1970)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 54, N° 1 (01/1970) . - p. 27-35 Titre : Consideration of the vegetable tannin chromium-collagen system Type de document : texte imprimé Auteurs : D. A. Williams-Wynn, Auteur Année de publication : 1970 Article en page(s) : p. 27-35 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuirs et peaux pH Prétannage Retannage Tanins végétaux Tannage au chrome Tannage combiné Le tannage combiné se dit des tannages qui allient deux familles ou genre de tannage pour obtenir un résultat additionnant les qualités complémentaires des tannins mis en Å“uvre par exemple Chrome-Végétal ou Chrome-Synthétique Tannage végétal Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Conclusions drawn from the experimental evidence of a series of publications are discussed and co-ordinated. Chromium pretannage of the collagen increases its reactivity towards vegetable tannins by liberating charged amino groups and other sites not normally available, with the result that vegetable tannins are rapidly absorbed in the surface layers of the skin, and this in turn causes over-loading of the fibre and increased cross-Iinking, both of which tend to give weak leather. In addition, it has been shown that vegetable tannins and non-tannins form co-ordination compounds with the chromium in the leather, displacing sulphate with a consequent increase in acidity. The possibility exists, especially in retanning with hydrolysable tannins, that protein carboxyl groups may be displaced from the chromium-collagen complex with the result that a degree of detannage occurs. Moreover, on ageing, the reaction of the vegetable tannins with the chromium-collagen complex continues, with the displacernent of additional sulphate groups and a further increase in acidity which is thought to promote the hydrolytic degradation of the protein and results in the deterioration of this type of leather. The strength of the leather can be improved by reducing the avidity of the chromium tanned pelt so that a more uniform distribution of the vegetable tannin is obtained, and durability is increased by the inclusion of compounds which react preferentially with the chromium-collagen complex and inhibit the entry of vegetable tannins so that the acidity of tne leather is maintained at a satisfactorily low levet. Choice of the type of vegetable tanning extract is also of importance; members of the hydrolysable group of tannins should be avoided because of their greater reactivity with chromium compared with the condensed tannins. Note de contenu : - Quantity of chromium offered - Basicity of chromium salt - Masking of chromium salt - Type of retanning material - Non-tannins in vegetable tanning extracts - Quantity of tannins offered - Temperature of retannage - pH of retannage - Type of collagen substrate - Ageing En ligne : https://drive.google.com/file/d/1vKDGZrdPAEOGIwDCaUcAkdzFfcQWcs08/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40721 [article]

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The effect of different acids in the warm circulator system sole leather tannage / D. A. Williams-Wynn in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 54, N° 10 (10/1970)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 54, N° 10 (10/1970) . - p. 348-355 Titre : The effect of different acids in the warm circulator system sole leather tannage Type de document : texte imprimé Auteurs : D. A. Williams-Wynn, Auteur Année de publication : 1970 Article en page(s) : p. 348-355 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Chimie analytique Cuirs et peaux Formique, Acide Lactique, Acide L'acide lactique est un acide organique qui joue un rôle dans divers processus biochimiques. Un lactate est un sel de cet acide. Contrairement à ce que peut laisser penser son nom, l'acide lactique n'est pas présent uniquement dans le lait, mais également dans le vin, certains fruits et légumes, et dans les muscles. L'acide lactique est un acide alpha hydroxylé, sa formule chimique est C3H6O3 et sa structure se reflète dans son nom systématique, l'acide 2-hydroxypropanoïque. Liqueurs de tannage Semelles Sulfurique, Acide Tannage Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : An investigation has been made of the use of formic acid, or lactic acid, or binary blends of these with each other, or with sulphuric acid, in place of sulphuric acid used alone for acidifying the warm circulator vegetable tan liquors. In each case the pelt had been pretreated in a standing pickle consisting of Calgon and sulphuric acid. Small differences due to the organic acids were noted, in particular increased water absorption but improved resistance to water penetration, when formic acid was used. However, there seemed to be no advantages in the use of lactic acid. Blends of acid tended to give results intermediate in effect between the use of the individual acids. In any event the effects noted were generally very small, and this may be the result of the relatively small amount of acid used for acidifying the tan liquors, since the pickle is the major source of acid in this tanning system. Note de contenu : - PHYSICAL PROPERTIES : Density, g/cc - Compressibility - Grain crack index - Water absorption Q24, % - Water absorption Kubelka, % - Dynamic water penetration minutes - Water penetration after redrying, minutes - Thickness, mm - Abrasion rate, mm/1000 throws - Shrinkage temperature, °C - CHEMICAL ANALYSES : Petrol ether extract, % - Water soluble matter, % - Hide substance, % - Fixed tans, % - Degree of tannage En ligne : https://drive.google.com/file/d/1F5iYFpESaQKm4D9BYwBmzqhHVFY1vL8W/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37020 [article]

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