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Tannin analysis - A 130 year problem / T. Waite in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 76, N° 6 (11-12/1992)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 76, N° 6 (11-12/1992) . - p. 187-194 Titre : Tannin analysis - A 130 year problem Type de document : texte imprimé Auteurs : T. Waite, Auteur Année de publication : 1992 Article en page(s) : p. 187-194 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Attempts to establish a workable method of evaluating the strength of vegetable tanning materials go back to the early part of the 19th century but the first method to achieve any real credence was that of Löwenthal developed in the 1860s. The problem was first addressed on an international scale at the London meeting of 1897 at which the first leather chemist’s society was founded. Many subsequent meetings have failed to produce agreement on an international method of analysis, making this subject the longest standing source of dispute on the international leather scene. This paper discusses the three Official Methods which currently co-exist, highlights some of the problem areas and makes some suggestions about their resolution. A more recent problem has been the use of these methods for estimating the tannin content of syntans, a purpose for which they were not originally envisaged and are unreliable, but for which no serious alternative have yet been promulgated. Note de contenu : - Origins of the problem - Löwenthal’s method - Detannisation - Development of the method - Discussion of methods - Experimental - Analysis of syntans En ligne : https://drive.google.com/file/d/1zaQn5K0BQNYS3ggVuRqQKX0BvKt3Y3oM/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12790 [article]

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Application of Cr(III) hydrolytic oligomers in leather tanning / T. Gotsis in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 76, N° 6 (11-12/1992)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 76, N° 6 (11-12/1992) . - p. 195-200 Titre : Application of Cr(III) hydrolytic oligomers in leather tanning Titre original : Part 1. Effect of sulphate on the tanning properties of dimer and trimer Type de document : texte imprimé Auteurs : T. Gotsis, Auteur ; L. Spiccia, Auteur ; K. C. Montgomery, Auteur Année de publication : 1992 Article en page(s) : p. 195-200 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The tanning efficiency of two hydrolytic oligomers of Cr(III), dimer, [(H2O)4Cr((µ-OH)2Cr(H2O)4]4+ and trimer, [Cr3(µ-OH)4(OH2)9]5+ has been examined in the presence and absence of sulphate. Althgough the oligomers alone produced tanned intestines with reasonable shrinkage temperature (Ts = 90-95°C), higher Ts values (99-110°C) were achieved when lamb intestine was tanned with oligomer solutions which contained sulphate. It is concluded that the reaction of sulphate with these oligomers produces Cr(III) sulphato complexes which are more effective at cross-linking collagen than the pure oligomers. Ts was found to vary systematically with chromium content for all intestines tanned in the presence of sulphate. Sulphato complexes produced from the reaction of trimer with sulphate appear to be more effective at cross-linking collagen than those produced from dimer. Higher Ts values were observed for trimer samples than for dimer samples containing the same number of molecules of each oligomer per unit weight. Ion-exchange chromatography has been used to separate the predominant sulphate complex formed by the reaction between the hydrolytic dimer and sulphate. Solution characterization studies have shown that the complex is a dimer with the likely formula [(H2O)4Cr((µ-SO4)(µ-OH)2Cr(H2O)3]2+ . Since this is essentially the sole product of the reaction of the sulphate with dimer, this complex must be responsible for the improved tanning qualities of dimer solutions on addition of sulphate. It is predicted to be of similar dimensions to the hydrolytic dimer (length ca. 8 A) and thus, is capable of cross-linking the collagen strands. The low overall charge (2+, cf 4+ for the hydrolytic dimer) is anticipated to facilitate migration of the complex to the binding sites. En ligne : https://drive.google.com/file/d/1Ige75TOF739cAavlOYUzg8fXSHLNHeMN/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12791 [article]

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Affinity for collagen of chromium complexes separated from masked chrome solutions / K. Takenouchi in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 76, N° 6 (11-12/1992)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 76, N° 6 (11-12/1992) . - p. 201-204 Titre : Affinity for collagen of chromium complexes separated from masked chrome solutions Type de document : texte imprimé Auteurs : K. Takenouchi, Auteur ; K. Kondo, Auteur ; F. Nakamura, Auteur Année de publication : 1992 Article en page(s) : p. 201-204 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : A hexaaquochromium solution was masked with formate, acetate, and oxalate. The masked chromium complexes were separated by ion exchange chromatography. Hide powder was tanned with the masked chromium complexes. The affinity of the masked chromium complexes for collagen varied with each individual complex. Among various kinds of masked chromium complexes, formatochromium complexes with a charge corresponding to +3 had the highest affinity for collagen at high pH and formatochromium complexes with a charge corresponding to +2 were second in affinity. Acetochromium complexes with a charge corresponding to +3 followed these complexes. Noncationic acetate-and oxalato- chromium complexes had low affinity. En ligne : https://drive.google.com/file/d/1tG1-oU5lQ4B82Er9DdBVt1rPdjCWM0MS/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12807 [article]

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Chitosan in leather production / Stephen M. Burkinshaw in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 76, N° 6 (11-12/1992)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 76, N° 6 (11-12/1992) . - p. 205-209 Titre : Chitosan in leather production Titre original : Part 5 : The enhancement of uptake of direct dyes and sulphur dyes on heavily retanned leather Type de document : texte imprimé Auteurs : Stephen M. Burkinshaw, Auteur ; M. F. Karim, Auteur Année de publication : 1992 Article en page(s) : p. 205-209 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The extent of uptake of C.I Solubilised Sulphur Black 1, C.I Direct Blue 106 and C.I Direct Black 155 onto heavily retanned chrome grain leather was enhanced by pretreatment with chitosan formate. The dyed pretreated samples were of a similar, but deeper colour and possessed superior fullness and handle to their dyed, untreated counterparts. Optical microscopy suggests that the extent to which the intensified shade extents within the pretreated leather is determined by substantivity and diffusional behavior of the dye within a layer of chitosan located at the surface of the substrate. En ligne : https://drive.google.com/file/d/1biB9OdB723qrOp4nPJGcG6LdmKWJlqVn/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12808 [article]

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SLTC draft fastness test method in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 76, N° 6 (11-12/1992)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 76, N° 6 (11-12/1992) . - p. 215-219 Titre : SLTC draft fastness test method : Test for adhesion of a finish to leather Type de document : texte imprimé Année de publication : 1992 Article en page(s) : p. 215-219 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Poor adhesion of the finish on a leather can give rise to flaking or peeling during manufacture or end use of an article. The adhesion test procedure described in this method is asimple one, designed for use in the tannery or factory was well as the laboratory. It is essentially a modified version of the one described. Note de contenu : - Scope and field application - Principle - Apparatus and reagents - Test specimens - Procedure - Validity of mode of separation - Test report - Suitable adhesives En ligne : https://drive.google.com/file/d/1jNYwIk5Dyo1U6dRVofl7Y4vGRLKEUo-I/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12810 [article]

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