Collagen D-spacing and the effect of fat liquor addition / Katie H. Sizeland in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CX, N° 3 (03/2015)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CX, N° 3 (03/2015) . - p. 66-71 Titre : Collagen D-spacing and the effect of fat liquor addition Type de document : texte imprimé Auteurs : Katie H. Sizeland, Auteur ; Hannah C. Wells, Auteur ; G. E. Norris, Auteur ; Richard L. Edmonds, Auteur ; Nigel Kirby, Auteur ; A. Hawley, Auteur ; S. T. Mudie, Auteur ; Richard G. Haverkamp, Auteur Année de publication : 2015 Article en page(s) : p. 66-71 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Collagène Lanoline Produits de nourriture du cuir Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The physical properties of leather are partly a result of the structure of the leather’s network of type I collagen fibrils. To achieve high strength and a soft, supple feel, penetrating oils (usually polyols) are added to leather during manufacture, and this process is known as fat liquoring. The modification of the collagen structure by fat liquoring (with a lanolin-based fat liquor) is investigated using synchrotron-based small angle X-ray scattering. The axial periodicity, or D-spacing, of the collagen changes as a result of fat liquoring. With no fat liquor, the D-spacing is 60.2 nm; spacing increases by 6% to 63.6 nm at 10% fat liquor. Pure lanolin results in a similar increase in D-spacing. We discuss mechanisms for fibril elongation brought about by fat liquoring. The observations of structural changes taking place within collagen fibrils as a result of fat liquoring provides new insight into the nature of fat liquoring and informs future processing developments. En ligne : https://drive.google.com/file/d/1OE6eYCsce54i3IpZmfe6cnLKLoymJuH-/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23451 [article]

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Effect of tanning agents on collagen structure and response to strain in leather / Katie H. Sizeland in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXI, N° 11 (11/2016)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXI, N° 11 (11/2016) . - p .391-397 Titre : Effect of tanning agents on collagen structure and response to strain in leather Type de document : texte imprimé Auteurs : Katie H. Sizeland, Auteur ; Hannah C. Wells, Auteur ; Richard L. Edmonds, Auteur ; Nigel Kirby, Auteur ; Richard G. Haverkamp, Auteur Année de publication : 2016 Article en page(s) : p .391-397 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Agents de tannage Chrome Collagène Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux de moutons Déchirure (mécanique) Déformations (mécanique) Essais dynamiques Mimosa et constituants Oxazolidine Résistance des matériaux Réticulation (polymérisation) Sulfate de tétrakis hydroxyméthyl phosphonium Le sulfate de tétrakis hydroxyméthyl phosphonium est un myxobactéricide qui offre une prévention efficace contre les biofilms microbiens dans les eaux de traitement, et ce, pour une vaste gamme de micro-organismes formant des biofilms. Le sulfate de tétrakis (hydroxyméthyl) phosphonium agit principalement en augmentant la perméabilité de la membrane externe de l'enveloppe de la cellule microbienne, ce qui entraîne la libération rapide de protéines et d'autres substances cellulaires par les cellules. En outre, le sulfate de tétrakis (hydroxyméthyl) phosphonium inhibe le processus de sulfatoréduction dans les bactéries réductrices de sulfate. Température de retrait Traction (mécanique) Zirconium Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : A variety of tanning agents are used to produce leather of different mechanical performances and properties. How different tanning agents affect the structure of leather, and consequently the mechanism underlying the performance of the differently tanned leathers, is not well understood. We used small-angle X-ray scattering to investigate the structure of ovine leather tanned with chromium, zirconium, mimosa, oxazolidine or tetrakis hydroxymethyl phosphonium sulfate (THPS), or selected pairs of these agents. Leather tanned using THPS and THPS in combination with mimosa retained the most oriented collagen fibril structure. Treatment with chromium, zirconium or zirconium and mimosa resulted in the least oriented fibril structures. The effect of oxazolidine with mimosa was intermediate between these. A high natural collagen fibril orientation in a skin is normally associated with high strength while a high degree of crosslinking normally results in a lower fibril orientation. We suggest that the extent of crosslinking in the samples is reflected in their fibril orientation, with more crosslinking producing stronger leathers. This interpretation is supported by the differences in shrinkage temperatures: those leathers for which orientation index (a measure of collagen fibril alignment) changed most had a lower shrinkage temperature (which is normally interpreted as more “tanning”). This provides a greater understanding of the mechanism of action of tanning agents in the development of the properties of leather. Note de contenu : - METHODS : Chromium (standard) - Zirconium - THPS - Oxazolidine + Mimosa - Zirconium + Mimosa - THPS + Mimosa - Mechanical testing - Shrinkage temperature - SAXS - RESULTS : Tear strength - Tensile strength - Stress-strain - SAXS - OI - OI and strain - d-spacing and stress - Shrinkage temperature En ligne : https://drive.google.com/file/d/18XKbg7Exz9EEkW0BlT9kl1eCqePq4zfO/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=27154 [article]

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Fatliquor effects on collagen fibril orientation and D-spacing in leather during tensile strain / Katie H. Sizeland in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CX, N° 11 (11/2015)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CX, N° 11 (11/2015) . - p. 355-362 Titre : Fatliquor effects on collagen fibril orientation and D-spacing in leather during tensile strain Type de document : texte imprimé Auteurs : Katie H. Sizeland, Auteur ; Geoff Holmes, Auteur ; Richard L. Edmonds, Auteur ; Nigel Kirby, Auteur ; A. Hawley, Auteur ; S. T. Mudie, Auteur ; Richard G. Haverkamp, Auteur Année de publication : 2015 Article en page(s) : p. 355-362 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Collagène Cuirs et peaux -- Propriétés mécaniques Déformations (mécanique) Distribution et orientation des fibres Essais dynamiques Produits de nourriture du cuir Test de déchirement Traction (mécanique) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Strength is a very important property of leather and is known to depend on the arrangement of the collagen fibrils within the material. The addition of fatliquor (penetrating oils) is an essential part of the manufacture of leather and enhances the strength and feel of leather. However, the mechanism by which fatliquor leads to increased strength is not understood. Here we use synchrotron based small angle X-ray scattering (SAXS) to monitor the collagen fibril rearrangement and internal strain of leather during tension. Differences in internal structural changes under strain with varying levels of fatliquor are investigated. It is found that when a strain of up to 40-70% was applied to leather, the orientation index (OI) of the collagen fibrils changed up to 21.8% and the d-spacing changed by up to 1.8% with no consistent differences at different levels of fatliquor. The extensibility of leather increases by 11.3% with as little as 2% fatliquor addition and the elastic modulus decreases with fatliquor addition but not in proportion to the amount of fatliquor. This change in extensibility is not reflected in differences in OI or d-spacing changes during strain. As reported previously, the fatliquor modifies the d-spacing of collagen. While fatliquor is traditionally considered to lubricate the fibers in leather, here the evidence suggests that this does not occur at the level of collagen fibrils. This provides an insight in the action of fatliquor in leather manufacture. Note de contenu : - Fatliquor addition - Scattering patterns - Tear test - Orientation index - Stress-strain - OI of cross sections En ligne : https://drive.google.com/file/d/1bwnG63Bg0OkZzrAzbZtmL75YrZ0abVXL/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=24864 [article]

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Mapping tear, strength and collagen fibril orientation in bovine, ovine and cervine hides and skins / S. J. Kelly in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. CXIII, N° 1 (01/2018)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. CXIII, N° 1 (01/2018) . - p. 1-11 Titre : Mapping tear, strength and collagen fibril orientation in bovine, ovine and cervine hides and skins Type de document : texte imprimé Auteurs : S. J. Kelly, Auteur ; Richard L. Edmonds, Auteur ; Sue M. Cooper, Auteur ; Katie H. Sizeland, Auteur ; Hannah C. Wells, Auteur ; T. Ryan, Auteur ; Nigel Kirby, Auteur ; A. Hawley, Auteur ; S. T. Mudie, Auteur ; Richard G. Haverkamp, Auteur Année de publication : 2018 Article en page(s) : p. 1-11 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuirs et peaux -- Analyse Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux de bovins Cuirs et peaux de cervidés Cuirs et peaux de moutons Diffusion aux petits angles Distribution et orientation des fibres Fibrilles de collagène La fibrille de collagène est une structure constituée d'un assemblage de fibres de tropocollagène (assemblage de 3 protéines de collagène alpha (alpha 1 - alpha 1 - alpha 2) en une hélice droite. Résistance à la déchirure Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Leather is a natural and variable material. The variation in strength has previously been shown to be due in part to the collagen fibril orientation. However, the extent of variation in strength and orientation over a skin/hide is not well established. Synchrotron small angle X-ray scattering is used to measure collagen fibril orientation (O) and orientation index (OI). Tear strength is measured in two orthogonal directions across ovine and cervine skins and bovine hides. Average normalized strengths varied between species with cervine leathers having the greatest overall strength followed by bovine then ovine leathers. Ovine had the greatest variability in strength across the skin. There were no obvious regions of generally stronger or weaker skin within individual skins or hides. The predominant collagen fibril direction was perpendicular to the backbone of all species, with the greatest perpendicular alignment in ovine followed by cervine. Collagen fibril orientation in leathers made from of ovine, bovine and cervine skins have been analyzed quantitatively and in detail. Findings suggest an unpredictable variability in collagen arrangements within each species but a notable difference in strength between species. Note de contenu : - METHODS : Leathers - Test samples - Tear strength - Small angle X-ray scattering (SAXS) - Orientation and orientation index - Samples - RESULTS : Tear strength - SAXS measurements - Variation of O in the OSP grid square sample - Orientation index - Orientation - Correlation between O and tear strength - Difference between belly and back En ligne : https://drive.google.com/file/d/18J4tLzzVaEGSbu3Mx6EnI4zz0Ct7Kl_y/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29744 [article]

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