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Collagen and polyphenols : new relationship and new outcomes. Part 1. Flavonoid reactions for new tanning processes / Anthony D. Covington in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. C, N° 9 (09/2005)
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Titre : Collagen and polyphenols : new relationship and new outcomes. Part 1. Flavonoid reactions for new tanning processes Type de document : texte imprimé Auteurs : Anthony D. Covington, Auteur ; L. Song, Auteur ; T. H. Lilley, Auteur Année de publication : 2005 Article en page(s) : p. 325-335 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The process of vegetable tanning is hindered by the astringency of the tannins, which affects the development of their use as organic tanning agents for modern purposes. The use of non tans, either from natural sources such as green tea or by degrading tannins into non tannins, avoids the problem of hindered penetration through pelt due to the high reactivity of the polyphenols. Both tannins and non tannins are capable of engaging in combination tannage with aldehydic agents, to confer high hydrothermal stability to collagen. The use of prodelphinidin or prorobinetinidin polyphenols, characterized by the presence of a pyrogallol B-ring, is preferred in this context. Also, the use of non tannins provides a practical route to modem organic tanning. En ligne : https://drive.google.com/file/d/15iPRhEGaqXGcbGEUN68FWrIxyzBvussz/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4054
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. C, N° 9 (09/2005) . - p. 325-335[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 003081 - Périodique Bibliothèque principale Documentaires Disponible Link lock : an explanation of the chemical stabilisation of collagen / Anthony D. Covington in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 92, N° 1 (01-02/2008)
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Titre : Link lock : an explanation of the chemical stabilisation of collagen Type de document : texte imprimé Auteurs : Anthony D. Covington, Auteur ; L. Song, Auteur ; Ono Suparno, Auteur ; H. E. C. Koon, Auteur ; M. J. Collins, Auteur Année de publication : 2008 Article en page(s) : p. 1-7 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Collagène -- Analyse
Cuirs et peaux
Dénaturation (chimie)
Oxazolidine
Polyphénols
Réticulation (polymérisation)
Stabilité chimiqueIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : Chemical modifications of collagen, of the type known in the leather tanning industry, can raise the denaturation temperature, from 60°C in its natural state, up to 130°C. There are only a few chemical reactions known to be capable of achieving the highest values and these have long been assumed to be unrelated. Here, we show for the first time that all the stabilising mechanisms are fundamentally the same, regardless of chemical type. Any single component of a stabilising reaction has the effect of linking part of the collagen structure into the surrounding matrix of water: the outcome is always to confer moderate hydrothermal stability, up to 85°C. The effect is merely to hinder the shrinking/denaturation transition, so no single component reaction can exceed this moderate result. However, in addition, a second reaction component can be applied in the process, which may have the ability to lock the linked structure together, creating a macromolecular structure around the triple helices. The effect of the concerted interaction with collagen is to prevent more effectively the unravelling of the triple helices and thereby to raise the hydrothermal stability to much higher values of denaturation temperature. This new proposed 'linklock' mechanism opens up the possibility of achieving high collagen stability in new ways, which will contribute to the development of new collagenic biomaterials. Note de contenu : - Table 1 : Typically observed effects on collagen denaturation temperature ranges of some chemical modifications
- Table 2 : The effects of crosslinking polyphenol with oxazolidine on the denaturation temperature, the synergy of the reaction and the effect on the hydrothermal stability of acetone washing to break hydrogen bonding (ΔTs)(°C)
- Table 3 : Relative rates of increase in tension after shrinking transition is initiated and relative rates of decrease in tension after the shrinking transition
- Table 4 : The stabilisation of collagen (as hide powder) by the combination of dihydroxy naphthalene and oxazolidineEn ligne : https://drive.google.com/file/d/1tiLCy85-VTxKSKpatCI-dBw-eoztRNiV/view?usp=share [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38914
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 92, N° 1 (01-02/2008) . - p. 1-7[article]Modification of larch extract by intensive sulfitation and applications of the product in combination tannages / Bi Shi in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. XCVII, N° 1 (01/2002)
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Titre : Modification of larch extract by intensive sulfitation and applications of the product in combination tannages Type de document : texte imprimé Auteurs : Bi Shi, Auteur ; Guangwei Du, Auteur ; L. Song, Auteur ; Ying Di, Auteur Année de publication : 2002 Article en page(s) : p. 1-7 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Larch bark extract, the condensed tannin with procyanidin structure, was modified by intensive sulfitation using 20% Na2SO3. This unusual treatment brought about degradation of tannin molecules and increased hydrophilicity of the product, whilst the synergistic effect of the modified product with Cr(III) was enhanced. As a result, 5-10% tannin compound was able to penetrate through pickled pelt in 1-2h without pre-treatment, and in conjunction with 1.0% Cr2O3, could produced leathers with shrinkage temperature above 110°C. Physical properties of the leathers were more comparable to common chrome leathers. The so-called vegetable tanned character was largely eliminated by such a small offer of vegetable compounds. The conditions of the chemical modification and the applications of the product are described in detail. En ligne : https://drive.google.com/file/d/1lciFN1_5mAkS22H_4dklRMYCtlnDsW0q/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4341
in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. XCVII, N° 1 (01/2002) . - p. 1-7[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 001570 - Périodique Bibliothèque principale Documentaires Disponible