Effect of retanning agents on dry heat resistance of leathers / Chao Wu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CVIII, N° 8 (08/2013)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CVIII, N° 8 (08/2013) . - p. 294-299 Titre : Effect of retanning agents on dry heat resistance of leathers Type de document : texte imprimé Auteurs : Chao Wu, Auteur ; Yunhang Zeng, Auteur ; Xuepin Liao, Auteur ; Wenhua Zhang, Auteur ; Bi Shi, Auteur Année de publication : 2013 Article en page(s) : p. 294-299 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agents de tannage Chaleur sèche Cuirs et peaux Résistance thermique Retannage Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : To obtain acceptable dry heat resistance of leather by using proper retanning agents, the effect of typical retanning agents on dry heat resistance was investigated. The results indicated that the leathers retanned by different retanning agents have varying dry heat resistance, and the dry heat resistance is not always positively correlated with hydrothermal stability. Heating leather at 150oC for 30 min in the dry state led to minor damage to the crosslinking of collagen fibers, such as destruction of hydrogen bonds or other weak crosslinks. The increase of water content in leather exhibits negative effect on the dry heat resistance. Therefore, it was observed that the retanning agent that has lower hydrophility lead to higher dry heat resistance of leather. In addition, it seems that the retanning agents with good filling property and thermal stability are effective in achieving high dry heat resistance of leather. Note de contenu : - EXPERIMENTAL : Materials - Retanning bu using different retanning agents - Characterization of leathers (analysis of dry heat resistance - Analysis of hydrothermal stability - Analysis of water content in leather - Analyses of FTIR - Thermogravimetric (TG) analysis) - Characterization of retanning - RESULTS AND DISCUSSION : Thermal stability of different retanned leathers - Analysis of leathers by FTIR spectroscopy - Effect of water content on dry heat resistance of leather - TG analysis En ligne : https://drive.google.com/file/d/1Ib8rQhCVbFwOrrdREO48SclCNjVOTwnR/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=19178 [article]

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A novel oxazolidine tanning agent and its use in vegetable combination tanning / Jing Li in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 95, N° 4 (07-08/2011)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 95, N° 4 (07-08/2011) . - p. 165-170 Titre : A novel oxazolidine tanning agent and its use in vegetable combination tanning Type de document : texte imprimé Auteurs : Jing Li, Auteur ; Sun Qingyong, Auteur ; Chao Wu, Auteur ; Xuepin Liao, Auteur ; Bi Shi, Auteur Année de publication : 2011 Article en page(s) : p. 165-170 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Mimosa et constituants Oxazolidine 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 organique Tannage végétal Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Combination tanning using vegetable tannins and oxazolidine E has been proved to be preferred alternative to chrome tanning. But this kind of tannage has not been widely applied partly owing to the high price of oxazolidine E. In this study, a new oxazolidine tanning agent, Oxazolidine SCU, was synthesized by using cheap and readily obtained raw materials, and its tanning properties both alone and in combination with vegetable tannins, were investigated. Oxazolidine SCU possesses high reactivity with skin collagen. Tanned by 5 % oxazolidine SCU under room temperature at pH8.0, the shrinkage temperature of goatskin leather was around 83°C. In vegetable combination tanning, oxazolidine SCU exhibited a good synergistic tanning effect with condensed tannins. Among condensed tannins, mimosa is the preferred one in consideration of achieving high shrinkage temperature of leather. Tanning the depickled pelt with 10-15 % vegetable tannin at first, and then retanning with 4-6 % oxazolidine SCU for 4 hours at 60°C in the pH range 5.5-6.0, the shrinkage temperature of leather was 114-120°C. Note de contenu : - EXPERIMENTAL PROCEDURE : Materials and instruments - Effect of tanning conditions on vegetable tannin-oxazolidine SCU combination tanning - Shrinkage temperature determination - RESULTS AND DISCUSSION : Hydrolysis of oxazolidine SCU - Effect of tanning conditions on tanning property of oxazolidine SCU - Effect of tanning conditions on vegetable tannin-oxazolidine SCU combination tanning En ligne : https://drive.google.com/file/d/1MQ9SW_udQTqwBWd5mGhdxqHM1IVNomnb/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=11860 [article]

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The further investigation of tanning mechanisms of typical tannages by ultraviolet-visible and near infrared diffused reflectance spectrophotometry / Junling Guo in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CVI, N° 7 (07/2011)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CVI, N° 7 (07/2011) . - p. 226-231 Titre : The further investigation of tanning mechanisms of typical tannages by ultraviolet-visible and near infrared diffused reflectance spectrophotometry Type de document : texte imprimé Auteurs : Junling Guo, Auteur ; Xin Huang, Auteur ; Chao Wu, Auteur ; Xuepin Liao, Auteur ; Bi Shi, Auteur Année de publication : 2011 Article en page(s) : p. 226-231 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Alun Glutaraldéhyde Groupement carboxyle Spectrométrie infrarouge Spectrophotométrie UV-Visible Spectroscopie de réflectance Sulfate d'aluminium Sulfate de chrome Sulfate de fer Sulfate de titane Sulfate de zirconium Tannage Tannage végétal Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The ultraviolet-visible and near-infrared diffuse reflection (UV-Vis-NIR DR) spectroscopy was employed for further understanding the mechanisms of three kinds of classical tannages, including aldehyde tanning, vegetable tanning and mineral tanning. The NIR DR spectra of glutaraldehyde tanned leather exhibited a decreased peak intensity of amino group at 1475 nm, suggesting that the main reaction groups of collagen in aldehyde tanning are amino groups. Comparing the NIR DR spectra of pickled pelt and vegetable tanned leather, it was proved that the vegetable tanning is based on the mechanism of multiple hydrogen bonding interaction, where the amino groups, carboxyl groups and peptide chains are involved. As for mineral tannages, the tanning mechanisms of chromium sulfate, zirconium sulfate, ferrum sulfate, titanium sulfate and aluminum sulfate were investigated. Based on UV-Vis-NIR DR analysis in the wavelength range of 200 to 2070 nm, it was confirmed that the main reactions involved in mineral tanning are the chelating interactions of metal ions with both the carboxyl groups and the amino groups of collagen, although the reactivity of metal salts toward carboxyl groups is higher than toward amino groups. The reactivity of metal salts toward carboxyl groups of collagen follows the sequence of chromium salt > zirconium salt > ferrum salt > titanium salt > aluminum salt. However, the reactivity of metal salts to amino groups of collagen is in the sequence of zirconium salt > chromium salt > ferrum salt > titanium salt > aluminum salt. Meanwhile, the peptide chain of collagen was also found to play an important role in fixation of metal ions during tanning process. Note de contenu : EXPERIMENTAL : Preparation of leather samples - UV-Vis-NIR DR determinations. RESULTS AND DISCUSSION : Comparison and analysis of DR spectra of CF, GA-CF and BT-CF - Comparison and analysis of DR spectra of metal salts tanned leathers. En ligne : https://drive.google.com/file/d/1XMCv5rwTd7b_YqA_uIwFpuqj1DFNGr8M/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12032 [article]

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Transposition of chrome tanning in leather making / Chao Wu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIX, N° 6 (06/2014)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIX, N° 6 (06/2014) . - p. 176-183 Titre : Transposition of chrome tanning in leather making Type de document : texte imprimé Auteurs : Chao Wu, Auteur ; Wenhua Zhang, Auteur ; Xuepin Liao, Auteur ; Yunhang Zeng, Auteur ; Bi Shi, Auteur Année de publication : 2014 Article en page(s) : p. 176-183 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Absorption Cuirs et peaux -- Propriétés mécaniques Eau -- Consommation -- Réduction Eaux usées -- Analyse Morphologie (matériaux) Oxydes de chrome Post-tannage Procédés de fabrication Récupération (Déchets, etc.) Stabilité hydrothermale Tannage au chrome Tannage organique Wet-white (tannage) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : To avoid the release of chrome from leather into post tanning effluents and the generation of chrome shavings, an inverse chrome tanning technology based on wet white was investigated. Conventional bated pelt was firstly tanned using an amphoteric organic tanning agent (Tingjiang white tanning agent, TWT) without pickling. Then, the TWT tanned wet white was directly processed with conventional post tanning processes. Chrome tanning was transposed to the end of the post tanning. The wet white had a shrinkage temperature (Ts) around 85°C that met the needs of shaving operation, and did not generate chrome shavings. The Ts and Cr2O3 content of the leather, by using this inverse chrome tanning technology, were higher than those of the conventional chrome tanned leather. With this inverse technology, the chrome output was reduced by 48%, mainly because no chrome was released from leather in post tanning processes. Meanwhile, the volume of chromium-containing wastewater discharged from the inverse processes was barely 31% of that from the conventional processes, which makes it much easier to collect and recover chromium from the effluents. Additionally, the tensile strength, tear strength and general appearances of the leather produced by the inverse technology were comparable to those of the conventional chrome tanned leather. Note de contenu : - EXPERIMENTAL : Materials - Leather making processes - Analyses of leather properties (Hydrothermal stability - Distribution of chrome in leather - Morphology of leather - Physical properties) - Analyses of effluents (Total organic carbon concentration (TOC) - Concentration of chrome in effluents - RESULTS AND DISCUSSION : pH change in leather making processes - Content and distribution of Cr2O3 in leather - Discharge of chrome from leather making processes - Absorption capacity of leathers of retanning and fatliquoring chemicals - Morphology in leathers -Physical properties of leathers En ligne : https://drive.google.com/file/d/1uviZiCwz4VgYvS-NNEWcomxG72XyP5nM/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21515 [article]

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