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Microscopic observations of leather looseness and its effects on mechanical properties / Cheng-Kung Liu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIV, N° 7 (07/2009)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIV, N° 7 (07/2009) . - p. 230-236 Titre : Microscopic observations of leather looseness and its effects on mechanical properties Type de document : texte imprimé Auteurs : Cheng-Kung Liu, Auteur ; Peter H. Cooke, Auteur ; Joseph Lee, Auteur ; Nicholas P. Latona, Auteur Année de publication : 2009 Article en page(s) : p. 230-236 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Looseness is a very troublesome issue regarding the structure of leather as well as the final leather product. It is a great concern to tanners who will go to great lengths to address it by adding different chemicals. However, its fine structure and effects on the mechanical properties are not fully understood. This investigation was devoted to gaining a better understanding of looseness based on microscopic studies showed visible gap between the interstitial layer and the corium layer in the loose leather. Moreover, the grain showed looseness leads to a decrease in toughness. However, measurements also showed there is little change in tensil strength and elongation. Moreover, viscoelasticity studies showed that loose leather has very similar stress relaxation curves as tight leather. Both leathers demonstrated a rapid decrease in stress for the first few seconds followed by a much slower decay thereafter. The loose leather, nevertheless, has a greater initial stress than the tight leather, indicating a higher stifness than tight leather. This study has provided a better understanding of loosenes, which will lead to the development of measures to correct this defect such as adding fillers to the leather. En ligne : https://drive.google.com/file/d/1rpVsSCRt8PaOTqzPuVa20pSVwplf5Wib/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5981 [article]

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Determination of metal load and extractable amounts in leathers dyed with metal-complex dyes / M. Mete Mutlu in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIV, N° 7 (07/2009)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIV, N° 7 (07/2009) . - p. 237-243 Titre : Determination of metal load and extractable amounts in leathers dyed with metal-complex dyes Type de document : texte imprimé Auteurs : M. Mete Mutlu, Auteur Année de publication : 2009 Article en page(s) : p. 237-243 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Heavy metals represent a major environmental problem in many industries and they may cause potential danger to human health when they are present in/on leather and textile and exposed long term contact with them in sweaty condition. The aim of this work was to determine the amount of metal ions in leathers dyed with 1:1 metal complex dyes and their extractable amounts by artificial sweat solution. Measurements were done by using inductively coupled plasma-optical emission spectrometry (ICP-OES). Total metal loads in leather samples were found between 115 and 1860 (min.-max. in mg/kg). Results in extraction solutions samples were found to be 0 to 6.55 (min.-max. in mg/L). The results obtained from the study were compared with the Oeko-Tex Standard limits and discussed. En ligne : https://drive.google.com/file/d/1NIOmzI2_AXv3OAtH5LF5EMx81AaKOeW7/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5982 [article]

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Molecular dynamic simulation study on the effect of water on the thermal stability of collagen polypeptide / Wenhua Zhang in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIV, N° 7 (07/2009)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIV, N° 7 (07/2009) . - p. 244-250 Titre : Molecular dynamic simulation study on the effect of water on the thermal stability of collagen polypeptide Type de document : texte imprimé Auteurs : Wenhua Zhang, Auteur ; Qiang He, Auteur ; Xuepin Liao, Auteur ; Bi Shi, Auteur Année de publication : 2009 Article en page(s) : p. 244-250 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Molecular dynamics simulations were carried out to investigate the effect of water on the thermal stability of a collagen polypeptide with 79 amino acid residues. All the simulations were performed using the Consistent Valence Force Field (CVFF) molecular mechanical force field and isothermal-isobaric ensemble (NPT). The theoretical parameters, root mean square deviation (RMSD) and root mean square fluctuation (RMSF) were used to evaluate the structura stability and flexibility of the collagen polypeptide, respectively. The initial geometries of the collagen polypeptide were from an x-ray crystallographic structure. The results obtained indicate that the presence of water is beneficial to keeping the crystal structure of collagen polypeptide. But water favors the flexibility of backbone atoms and amino acid residues owing to the formation of water-polypeptide hydrogen bonds. Therefore, the triple helix structure of polypeptide is easier to collapse in the presence of water with rising temperature compared with that without water. Dehydration leads to a remarkable increase of inter-chain and intra-chain hydrogen bonds, so that th collagen polypeptide chains are more tightly combined with each other. As a result, the configurations of dehydrated collagen polypeptide depart from the initial configuration, and collagen polypeptide possesses less flexibility and higher thermal stability. En ligne : https://drive.google.com/file/d/13RXX0nPDdI5g8wu51Rb32JE2fZyZgZzM/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5983 [article]

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Studies on the development of a multi-functional syntan / R. Nataraj in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CIV, N° 7 (07/2009)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CIV, N° 7 (07/2009) . - p. 251-260 Titre : Studies on the development of a multi-functional syntan Type de document : texte imprimé Auteurs : R. Nataraj, Auteur ; Rathinam Aravindhan, Auteur ; Kalarical Janardhanan Sreeram, Auteur ; Jonnalagadda Raghava Rao, Auteur ; Balachandran Unni Nair, Auteur Année de publication : 2009 Article en page(s) : p. 251-260 Note générale : Bibliogr. Langues : Américain (ame) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Innovations in recent years brought radical changes in leather processing. A trend has been set for bioprocessing in place of chemical processing. Enzymatic dehairing, lime free fiber opening, pH static and transposed processes have been developed to reduce pollution loads, essentially from pre-tanning operations. The demand for eco-labeled leather and leather products is gaining importance in the global leather industry. This ha forced the chemical manufactures to look for suitable alternative chemistry for preparation of syntans. Post-tanning operations, primarily the retanning process, employ mostly phenol and formaldehyde based agents to obtain fullness. Further, the post tanning operations use a combination of syntans to achieve the desired grain tightness, fullness and roundness. Many of these chemical are slow biodegradable and hence affect the environment significantly. A need has been sensed to develop products for retanning, which are devoid of phenols, formaldehyde and neutral salts. This work reports the development and use of a multifunctional syntan ; a product developed from solid wastes and biodegradable natural materials as an alternative to conventional phenol-formaldehyde based products in retanning for upper leathers. Physico-chemical analysis, morphological studies and emission loads have been compared. The product provides a synergistic effect on the leather as compared to the unifunctional properties offered by conventional phenol-formaldehyde syntans. En ligne : https://drive.google.com/file/d/1KxapuTN8cgIc8a6Y7G2ghmcwQSur3fBE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=5984 [article]

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