Current trends in leather science / Anthony D. Covington in JOURNAL OF LEATHER SCIENCE AND ENGINEERING, Vol. 2 (Année 2020)  

[article]  inJOURNAL OF LEATHER SCIENCE AND ENGINEERING > Vol. 2 (Année 2020) . - 9 p. Titre : Current trends in leather science Type de document : texte imprimé Auteurs : Anthony D. Covington, Auteur ; William R. Wise, Auteur Année de publication : 2020 Article en page(s) : 9 p. Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Chaulage Chimie -- Essais et réactifs Cuir -- Séchage Cuir végétal Cuirs et peaux -- Finition Cuirs et peaux -- Séchage Cuirs et peaux -- Teinture Epilage Produits de nourriture du cuir Tannage Tannage au chrome Tannage minéral Tannage dans lequel interviennent différents minéraux. Le plus répandu est le tannage aux sels de chrome, mais aussi à l’aluminium Tannage végétal Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : In preparing the second edition of ‘Tanning Chemistry. The Science of Leather.’, the literature was updated and the content was revised and reviewed. Here, the new findings are presented and discussed. Notable developments include the necessary rethinking of the mechanism of sulfide unhairing because of new understanding of the aqueous chemistry of sulfide species. Revision upwards of the value of the second pKa for sulfide species ionisation means that S2− cannot exist in an aqueous medium, so the unhairing species in hair burn reactions is HS−. Although the technology remains the same, this means the mechanisms of associated reactions such as immunisation must be revised. Rawstock preservation has benefitted from studies of the potential role of materials from plants which accumulate salt, but which also contribute terpene compounds. There is also further discussion on the continuing issue of chromium (VI) in the leather industry. The application to processing of new solvents, ionic liquids and deep eutectics, is the coming technology, which offers transforming options for new chemistries and products. Renewed interest in vegetable tanning and methods of wet white processing are current trends. Also, within the topic of reagent delivery is processing in a solid medium of plastic beads. Note de contenu : - Preservation - Unhairing - Liming - Chrome tanning - Mineral tanning - Vegetable tanning - Other tannages - Post tanning - Dyeing - Fatliquoring - Reagent delivery - Drying - Finishing Table 1 : Melting points of some ionic compounds DOI : https://doi.org/10.1186/s42825-020-00041-0 En ligne : https://link.springer.com/content/pdf/10.1186/s42825-020-00041-0.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37461 [article]

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Investigating the cell rotary conditioning mechanism using dynamic mechanical thermal analysis / Karl Flowers in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CX, N° 10 (10/2015)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CX, N° 10 (10/2015) . - p. 317-325 Titre : Investigating the cell rotary conditioning mechanism using dynamic mechanical thermal analysis Type de document : texte imprimé Auteurs : Karl Flowers, Auteur ; Adriano Peruzzi, Auteur ; William R. Wise, Auteur ; Anthony D. Covington, Auteur Année de publication : 2015 Article en page(s) : p. 317-325 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Absorption Adsorption Analyse thermomécanique dynamique Calorimétrie Cuirs et peaux -- Séchage Désorption Gravimétrie (chimie analytique) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Jeyapalina et al. established that dynamic mechanical thermal analysis (DMTA) can be used to gauge the progression of leather drying. This work has now been advanced in order to understand the mechanism surrounding sorption/desorption of moisture during cell conditioning, e.g., cell rotary conditioning (CRC). This paper will demonstrate how the use of DMTA could be used to monitor changes in leather stiffness. A gravimetric moisture analysis was performed on identical leather samples to gauge the progression of desorption. The change in storage modulus (E’) was coupled to the moisture content (leather moisture and atmospheric relative humidity) to obtain a better understanding of the physical properties (specifically stiffness) of leather during a drying process. The research presented illustrates how DMTA can indicate leather fiber response to changes in atmospheric humidity and facilitate real-time adaptation of drying conditions during leather dehydration. The use of a cell conditioning system allows a tanner to control the flexibility of the material through the tension applied and the drying conditions. DMTA shows that the favorable conditions inside a CRC unit result in detectable changes to the leather fiber, similar to findings by Abrahamson and Williams-Wynn. Using this technique a researcher can dry chromium-containing and chromium-free leathers in a manner that is highly customizable to produce desired physical properties. Difficulties experienced in chromium-free leathers can also be investigated in detail using this technique. Note de contenu : - INTRODUCTION : Drying literature - Drying methods - Sorption/desorption of water - Effects of heat and moisture on leather - Dynamic mechanical thermal analysis - EXPERIMENTAL : Leather raw materials - Conditioning - Dynamic mechanical thermal analysis - Differential scanning calorimetry - RESULTS AND DISCUSSION : Leather raw materials (gravimetric analysis) - Static thermal studies - Dynamic thermal studies En ligne : https://drive.google.com/file/d/1gSTYiwGRroeFzPGRHmK24blXV07LBXW7/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=24742 [article]

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Investigation into deep eutectic solvents / Andrew Abbott in LEATHER INTERNATIONAL, Vol. 217, N° 4860 (05/2016)  

[article]  inLEATHER INTERNATIONAL > Vol. 217, N° 4860 (05/2016) . - p. 26-31 Titre : Investigation into deep eutectic solvents Type de document : texte imprimé Auteurs : Andrew Abbott, Auteur ; A. Paula M. Antunes, Auteur ; Anthony D. Covington, Auteur ; Bokamoso Mmapatsi, Auteur ; William R. Wise, Auteur ; James Thomas Guthrie, Auteur Année de publication : 2016 Article en page(s) : p. 26-31 Langues : Anglais (eng) Catégories : Cuirs et peaux de chèvres Eau -- Consommation -- Réduction Eutectiques Un eutectique est un mélange de deux corps purs qui fond et se solidifie à température constante, contrairement aux mélanges habituels. Il se comporte en fait comme un corps pur du point de vue de la fusion. C'est aussi le point du diagramme (mélange avec une proportion donnée) pour lequel le mélange est à sa température minimale en phase liquide. Cette température est propre à chaque mélange. pH Poudre de peaux solvants Stabilité hydrothermale Tannage au chrome Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Novel deep eutectic solvents for the purpose of the reduction of water usage in leather manufacturing. Water in the wet processes of leather manufacture acts as a solvents, transportation medium, support system and is an integral component of the collagen matrix stability at the macro and molecular levels. There have been proposals as to what extent water can be substituted with non-aqueous media, partly due to its role in collagen and processing. As the water content increases from bulk to float water, the system acts as a transport medium for chemicals as well as a support system in processing vessels. Here, deep eutectic solvents (DESs) are investigated as an alternative solvent system to conventional tanning systems. Note de contenu : - TABLE : The cabinet conditions of leather samples prior to testing - FIGURES : 1. Schematic representation of a eutectic point on a two component phase diagram - 2. The effect of substrate water content on the hydrothermal stability of chromium tanned goatskin powder processed with the type 2 DES system - 3. The effect of pH on the hydrothermal stability of goatskin powder processed with the type 2 DES system, pH was varied by 2, 4, 6 and 8 - 4. The effect of temperature on the hydrothermal stability of goatskin powder chromium tanned with the type 2 DES system - 5. The effect of chromium concentration on hydrothermal stability of goatskin powder processed with the type 2 DES system - 6. Effect of the sulphate counterion on the hydrothermal stabilty of the type 2 DES processed goatskin powder En ligne : https://drive.google.com/file/d/1dCIvT1t_zJ78VzwSamrLBy56i_NzYigF/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26468 [article]

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Tanning chemistry / Anthony D. Covington / Londres [Royaume-Uni] : The Royal Society of Chemistry (2020)

Titre : Tanning chemistry : the science of leather Type de document : texte imprimé Auteurs : Anthony D. Covington, Auteur ; William R. Wise, Auteur Mention d'édition : 2nd Edition Editeur : Londres [Royaume-Uni] : The Royal Society of Chemistry Année de publication : 2020 Importance : XXV-685 p. Présentation : ill. Format : 24 cm ISBN/ISSN/EAN : 978-1-78801-204-1 Note générale : Index - Bibliogr. Langues : Anglais (eng) Catégories : Cuirs et peaux Tannage Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : This book offers a state-of-the-art view of leather making, based on the scientific principles underpinning the technology. In particular, it contributes to the understanding of the modern leather industry, allowing practitioners to make judgements about day-to-day problems in the tannery and how change can be applied in a predictable way. Major themes running through the book are the economics and environmental impact of leather making and how these will ensure the sustainability of the industry. This second edition of Tony Covington’s Tanning Chemistry is a revision, update and extension in collaboration with a new co-author, Will Wise. The update reflects the advances made in the past decade, including a discussion of the impact of new information concerning the chemistry of sulfide. The original chapters have been re-organised and new chapters on novel modes of reagent delivery and the principles of finishing are now included. Enzymology is addressed as a separate topic, as are environmental impact and the future of leather. The book will be useful to all those involved in the supply chain, from farm, through students, chemical suppliers and tanners, to leather goods brands. Leather science is the key to understanding leather technology, to make it work, to make it work better and to keep it ahead of the competition. Note de contenu : - Glossary of terms - 1. Collagen and skin structure - 2. Skin and its components - 3. Curing and preservation of hides and skins - 4. Soaking - 5. Unhairing - 6. Liming - 7. Deliming - 8. Bating - 9. Pickling - 10. Tanning - 11. Mineral tanning : Chromium(III) - 12. Mineral tanning - 13. Vegetable tanning - 14. Other tannages - 15. Post-tanning - 16. Dyeing - 17. Fatliquoring - 18. Enzymology - 19. Reagent delivery - 20. Drying - 21. Finishing - 22. Environmental impact - 23. Theory of tanning : the concept of link-lock - 24. The future of tanning chemistry - 25. The future of leather Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36786

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• Tanning chemistry / Anthony D. Covington / Tony Covington (2009)

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The impact of lowering the Cr(VI) detection limit in leather : implications on quantitative analysis / S. J. Davis in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 106, N° 4 (07-08/2022)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 106, N° 4 (07-08/2022) . - p. 191-195 Titre : The impact of lowering the Cr(VI) detection limit in leather : implications on quantitative analysis Type de document : texte imprimé Auteurs : S. J. Davis, Auteur ; William R. Wise, Auteur Année de publication : 2022 Article en page(s) : p. 191-195 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse quantitative (chimie) Chimie analytique -- Normes Chromatographie Colorimétrie Cuir -- Teneur en chrome hexavalent Cuirs et peaux -- Analyse Produits chimiques -- Détection Risques pour la santé Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The topic of chromium (VI) in leather has been debated by the whole supply chain for years. Its significance has recently been raised due to release of a consultation document by the European Chemicals Agency on skin sensitising substances, in which it was proposed that the acceptable Cr(VI) concentrations in leather goods should be lowered from 3ppm to 1 ppm. The proposition of a stricter limit and analytical difficulties at the current 3ppm compliance limit advocate the need for a review of current standards. Recent research by the Institute for Creative Leather Technologies (ICLT) has investigated both the colorimetric (Part 1) and chromatographic (Part 2) methods under BS EN ISO 17075. The focus of the study was to identify possible sources of interference leading to false results, and calculate the limit of quantification with respect to the proposed new compliance limit. Studies into the colorimetric method have shown the presence of Cr(III), dyes and proteins can be significant interferences becoming critical at low Cr(VI) concentrations. Dilution factors lead to the detection of < 1 pM Cr(VI) in solution and BS EN ISO 17075-1 were concluded to be not capable of resolving to 3ppm or 1 ppm in leather. Possible improvements to test methods are discussed although these would still not allow a lppm detection. It is suggested the ion-chromatographic (IC) aspect of BS EN ISO 17075-2 should be coupled to an inductively coupled plasma (ICP) ionisation system with mass spectrometry (MS) detector to enhance detection limits. Note de contenu : - Methodology - Direct Cr(VI) detection (BS EN ISO 17075-2:2017 annex B) method conditions - Chromatographic conditions with post-column DPC reaction (BS EN ISO 1707562/2017 annex C) - Recommendations - Table 1 : Concentrations of Cr(VI) in solution equating to the current and proposed compliance limits in leather - Table 2 : Limits of quantification for the colorimetric and chromatographic methods of BS EN ISO 17075 - Table 3 : Interlaboratory reproducibility data of the colorimetric and chromatographic methods of BS EN ISO 17075 at a 3ppm compliance limit - Table 4 : Average accuracies of the BS EN ISO 17075 test methods at the solution concentrations relating to the current compliance limits En ligne : https://drive.google.com/file/d/1vWzvxQ7MI6hRFXV1Gu3glO7ACHO-U0Qj/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37884 [article]

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The use of profilometry to characterise the leather surface / Prosper Mhute in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 101, N° 1 (01-02/2017)  

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Use of viscoelastic changes to demonstrate the relationship between drying parameters - A prelaminary study / William R. Wise in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXI, N° 1 (01/2016)  

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