Influence of retanning of the adsorption capacity of water on cattlehide collagen fibers / Keyong Tang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIV, N° 11 (11/2009)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIV, N° 11 (11/2009) . - p. 367-374 Titre : Influence of retanning of the adsorption capacity of water on cattlehide collagen fibers Type de document : texte imprimé Auteurs : Keyong Tang, Auteur ; Dominick J. Casadonte, Auteur ; Dennis C. Shelly, Auteur ; Jie Liu, Auteur ; Ming Yang, Auteur ; Xuejing Zheng, Auteur Année de publication : 2009 Article en page(s) : p. 367-374 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Adsorption Collagène Cuirs et peaux Tannage Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : There are an abundance of hydrophilic groups in the collagen fibers in leathers. Because the affinity between these hydrophilic groups and water molecules varies with changes in temperature and relative humidity, leathers will adsorb or de-adsorb water as these factors change; affecting strength, permeability, and thermal stability. Retanning is a key operation in leather making with the purpose of retanning is to obtain leathers with some special characteristics. The water content in leathers, often 15-20 wt%, is an amount that cannot be neglected. However, few reports are found on the interactions between collagen and water, particularly the influence of retanning on the interaction between water and collagen fibers. The state that water molecules exist in collagen fibers, the mechanism for collagen fibers to adsorb water, the de-adsorption kinetics for water molecules to escape from collagen fibers, and the influence of retanning on the adsorption of water on collagen fibers need to be studied to improve the leathermaking technology for controlling the structure and behaviors of leathers. In this study, after being chrome tanned, collagen fibers were retanned with chrome, glutaraldehyde, TGR retanning agent (proprietary acrylic based), and wattle extract, respectively, to obtain different retanned samples. The water adsorption isotherms of the samples were determined by using a gravimetric method, by which the influence of retanning on the equilibrium water adsorption capacity and the influencing mechanism were evaluated. Different retanned samples varied in water adsorption characterization and equilibrium adsorption capacity. The TGR retanning increased the equilibrium adsorption capacity, while glutaraldehyde retanning decreased it; likely related to differences in retanning mechanisms. For different relative humidity environments, leathers should be retanned with different retanning agents to get an optimum property. Based on the adsorption characterization and the equilibrium adsorption capacity for the samples, different mathematics models were used to describe the adsorption process and the adsorption mechanism. Six models were chosen to fit the experimental data, and it was found that the Bradley model was the best to describe the adsorption. En ligne : https://drive.google.com/file/d/1Rv1WvrffcvoLu3ITj9Od-y-F5wT4O2l2/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=6385 [article]

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Modification of polyurethane finishing agent using collagen hydrolysate from chrome shavings / Keyong Tang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CV, N° 1 (01/2010)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CV, N° 1 (01/2010) . - p. 25-31 Titre : Modification of polyurethane finishing agent using collagen hydrolysate from chrome shavings Type de document : texte imprimé Auteurs : Keyong Tang, Auteur ; Dominick J. Casadonte, Auteur ; Dennis C. Shelly, Auteur ; Wei Li, Auteur ; Xuejing Zheng, Auteur Année de publication : 2010 Article en page(s) : p. 25-31 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuirs et peaux -- Finition Hydrolysats de protéines Perméabilité Polyuréthanes Propionique diméthylol, Acide Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Finishing with traditional polyurethane finishing agents often dramatically drecreases the permeability of finished leathers. Continuing attempts have been made in recent years to develop aqueous polyurethanes (PU) finishing agents with better overall balance of properties while retaining characteristic high durability. Research in our industry has also included many studies to optimize use of the collagen available from chrome shavings. Collagen hydrolysate may contain a number of hydrophilic groups such as carboxylic, hydroxylic, amino, imino, and amide. The reactions between these collagen hydrolysate active groups and the urethane reactive groups (-NCO) resulted in the synthesis of new polyurethane finishing agents which offered increased permeability. The optimum collagenhydrolysate modifying condition forthis polyurethane finishing agent was found to be : DMPA, 5 % of the monomers by weight, reaction temperature of 80°C and reaction time of 2.5 hours. When the collagen hydrolysate is in the range of 0.6-0.8 % of IPDI by weight, a range of good properties is achievable. For example, when collagen hydrolysate is 0.6 % of IPDI by weight, the modified polyurethane finishing agent has high strength appropriate for use in basecoat or topcoat finishes. When the collagen hydrolysate is 0.8 % of IPDI by weight, the modified polyurethane finishing agent has good elongation at break and extensibility, indicating a potential aplication in leather sealing finishes. Note de contenu : - EXPERIMENTAL : Materials and apparatus - Procedures - - RESULTS AND DISCUSSION : Factors affecting the modification - Properties of the product - Verification of the modification - Table 1 : Effect of temperature on reaction - Table 2 : Effects of DMPA concentration on the reaction - Table 3 : WVTR of leathers finished by different finishing agents - Table 4 : WVTR of leathers finished with PU finishing agents modified with different amounts of collagen hydrolysate En ligne : https://drive.google.com/file/d/1B2kjPTjBb-Flo2WtH6JzDg8SJHd4BK1K/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8085 [article]

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Thermal shrinkage effects on the mechanical behavior of leathers / Keyong Tang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CV, N° 3 (03/2010)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CV, N° 3 (03/2010) . - p. 94-99 Titre : Thermal shrinkage effects on the mechanical behavior of leathers Type de document : texte imprimé Auteurs : Keyong Tang, Auteur ; Dominick J. Casadonte, Auteur ; Xuejing Zheng, Auteur ; Pengxiang Jia, Auteur ; Dennis C. Shelly, Auteur Année de publication : 2010 Article en page(s) : p. 94-99 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Thermal shrinkage will take place when leathers are heated to a high temperature, usually resulting in a decrease in its value and utility. In this paper, changes in mechanical behavior by thermal shrinkage of leathers are studied systematically for the first time, and the influencing mechanism of thermal shrinkage on the mechanical behaviors of leathers are investigated and analyzed. The results indicate that, by thermal shrinkage, the aperture ratios of leathers are decreased and such mechanical properties of leathers as elastic modulus, tensile strength, and elongation at break are increased. The improvement in mechanical behaviors by hydrothermal shrinkage is at the cost of loss of utility and economic value of leathers. The results indicate that shrunken leather may have a host of new applications because of their excellent mechanical behavior. En ligne : https://drive.google.com/file/d/1sjBf-VkgfBN_tLGI1ODfnNk76RaLpUfg/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8734 [article]

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