Grain crack and burst strength / Karl Flowers in INTERNATIONAL LEATHER MAKER (ILM), N° 37 (09-10/2019)  

[article]  inINTERNATIONAL LEATHER MAKER (ILM) > N° 37 (09-10/2019) . - p. 54-58 Titre : Grain crack and burst strength Type de document : texte imprimé Auteurs : Karl Flowers, Auteur Année de publication : 2019 Article en page(s) : p. 54-58 Langues : Anglais (eng) Catégories : Anisotropie Collagène Cuirs et peaux -- Propriétés mécaniques Essais de résilience Essais dynamiques Lubrification Matériaux -- Fissuration Résistance à l'éclatement Résistance à la fissuration Stratigraphie Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : Leather is a collagen skeleton that has chemical groups attached to it, which can either enhance its natural strength or annihilate it. Collagen is a rope-like network, three-dimensionally woven into a net-like mesh. The rope-like fibres can be dispersed so that they operate more independently, or they can be crowded together to move with restriction, causing them to feel dense and full. The spaces between the fibres and fibre bundles can be filled with interstitial materials that again restrict the freedom of fibre movement and, quite importantly, they can lower the porosity of the leather. Dense fibre structures begin to operate like reinforced concrete, the central fibre and surrounding packing material begin to co-operate as one unit and the collective strength they have is significantly higher than one fibre's individual strength. The lubrication (plasticisation) of the fibres is also critical to material strength. The individual fibres must be made to be flexible to ensure movement and strength. The opposite effect - adding a retan to the fibre that makes it more brittle the opposite of the lubricating effect mentioned above. Leather is anisotropic, topographically and stratigraphically. The focus of this article will be on the stratigraphic anisotropy - the phenomenon that considers fibre size and behaviour differences, as one transits from the grain to the flesh. Note de contenu : - Crack and burst testing - Brittle grain - The influence of tanning - Lubrication of the grain - Fig. 1 : A hand powered lastometer - the apparatus used for ball and grain burst - Fig. 2 : The clamp assembly of the lastometer showing a grain rupture (arrow) - Table 1 : Current industry methods that test the ability of a leather to resist the grain from cracking En ligne : https://drive.google.com/file/d/133e7dlqFVeWW24uJR5TwZAZgx7Cbi1vl/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33624 [article]

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A new concept of pretanning without chrome / Marcel Siegler in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXIV (Année 1979)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXIV (Année 1979) . - p. 288-300 Titre : A new concept of pretanning without chrome Type de document : texte imprimé Auteurs : Marcel Siegler, Auteur Année de publication : 1979 Article en page(s) : p. 288-300 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Chaux Croûte (cuir) On entend par "cuir en croûte" des cuirs ayant subi les opérations jusqu'au tannage, à l'exclusion de toute opération de corroyage ou de finissage, mais qui, par opposition aux wet-blue ont été séchés. Cuirs et peaux -- Propriétés physiques Fleur du cuir Prétannage sans chrome Refente sur chaux Stratigraphie Température de retrait Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : The manufacture of grain and split leather is simplified by pretanning cattle hides, either after bating or during pickling, with a chromium-free tanning agent until the shrinkage temperature reaches between 170° and 185°F. The pretanned hide is then split to provide a grain and a split intermediate, then these components are shaved and tanned. The entire hide treatment sequence can be effected in two stages : first, beaming, lime fleshing (if necessary), bating, and pretanning before or during pickling ; second, wringing, splitting, sorting, and shaving. The tanning is done after shaving in the the second stage and is followed by coloring and fatliquoring. The resulting chrome-tanned leather has very good physical properties, good fullness, and produces a higher area yield. The pretanned splits can be sorted and shaved for different types of leather, such as vegetable tan, chrome-vegetable tan, etc., and thus be increased in their value. The shavings contain no chromium and very littls salt. Hence they have many moreuses, or they can be disposed of by dumping without significant environmental impact. Much less chrome is needed to tan the leather because the tanning chemicals are used only on the shaved weight. Also, there is less spent chrome to be recycled and reused. The spent liquor can be used either as the float for a new batch of grains or for tanning the splits. Note de contenu : - Table 1 : Shrinkage temperatures at various stages of pretanning process - Table 2 : Take-up of the pretanning product with time of tanning - Table 3 : Chrome distribution by stratigraphic test regular tanning process - Split in blue versus seton special process (SSP) - Table 4 : Comparison of the physical properties of crust leathers derived from hides processed by lime splitting,blue splitting, and the SSP pretanning process - SSP pretanning procedure on regular delimed stock - SSP pretanning procedure on completely delimed stock - Tanning procedure for the grains - Physical properties of SSP leathers En ligne : https://drive.google.com/file/d/1ww_q_dWcvIGk6Usu7pBqWdiTGV_Undii/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37222 [article]

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Stratigraphic analysis of kangaroo leathers / L. J. Stephens in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXII (Année 1987)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXII (Année 1987) . - p. 41-44 Titre : Stratigraphic analysis of kangaroo leathers Type de document : texte imprimé Auteurs : L. J. Stephens, Auteur Année de publication : 1987 Article en page(s) : p. 41-44 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Cuirs et peaux -- Analyse Cuirs et peaux -- Propriétés mécaniques Cuirs et peaux de kangourous Stratigraphie Traction (mécanique) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The tensile strength and elongation at break of trata of kangaroo leather has been determined and compared with bovine leather splits. The kangaroo leather haad higher strength retention for all splits in comparison with calf leather figures from the literature. It was concluded that higher strength splits could be expected in lightweight kangaroo leathers of similar substance to calf leather. En ligne : https://drive.google.com/file/d/1w9400FOfCsBZCO0RubRAC4_JlJ7SqCVu/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8968 [article]

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