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Comparison of leather produced from fresh and salted hides / Betty M. Haines in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 59, N° 6 (11-12/1975)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 59, N° 6 (11-12/1975) . - p. 161-171 Titre : Comparison of leather produced from fresh and salted hides Type de document : texte imprimé Auteurs : Betty M. Haines, Auteur Année de publication : 1975 Article en page(s) : p. 161-171 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuir Echantillonnage Etudes comparatives Mesure Peaux brutes Rendement en surface Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The introduction of stringent effluent regulations is encouraging a change from traditional curing methods to the processing of fresh hides. The question then arises as to the quality of the leather and the area yield obtainable from fresh hides compared with salted. This comparison was made in three separate trials using 100 fresh and 100 wet salted hides in each trial. Data such as weight, thickness and area of the raw hides was recorded. A proportion of the hides were examined at stages through the processing, and the final leathers were subjected to physical tests. Apart from a slightly coarser break in the leathers produced from the fresh hides, no consistent differences in handle or physical properties relating to the curing methods could be found in the leathers. When the yield of leather was estimated on a weight basis either tail or green fleshed weight, no statistically significant difference in yield was found between the two curing methods. As the raw hides of the same weight differed considerably in area and thickness, a more precise basis for calculation of yield is one based on area. This was calculated for 50 hides in each of the three packs. Overall no statistically significant difference in yield was found relating to the curing methods. From this work we have concluded that there is no consistent difference between fresh and salted hides with regard to the yield and quality of leather produced from them. Note de contenu : - EXPERIMENTAL PLAN : Processing - Measurements made - Sampling for laboratory investigation - RESULTS : Variation in the raw material - Area yield - Leather quality - DISCUSSION : Variations in raw material - Area yield - Processing - Leather quality - Microscopical observations En ligne : https://drive.google.com/file/d/1NvhT8uz8VDV5OLNZO5mF4cpG2UU4iGPL/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31862 [article]

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The viscoelastic properties of leather and poromerics / R. E. Whittaker in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 59, N° 6 (11-12/1975)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 59, N° 6 (11-12/1975) . - p. 172-180 Titre : The viscoelastic properties of leather and poromerics Type de document : texte imprimé Auteurs : R. E. Whittaker, Auteur Année de publication : 1975 Article en page(s) : p. 172-180 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuirs et peaux -- Propriétés mécaniques Viscoélasticité Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The viscoelastic properties obtained from tensile stress-strain curves on leather and a number of poromerics are compared. It is found that a unique correlation exists for all shoe upper materials between the energy input to a stress-strain cycle and the hysteresis in that cycle. The amount of tension-set at a particular strain for leather is larger than for the poromerics and this gives leather an enhanced comfort property. The paper shows how this initial set is related to the amount of stress softening (difference between first and subsequent extension curves) in the material. The change of tension set with time of recovery, after extension to a particular strain, is shown to be similar for leather and poromerics. Note de contenu : - Stress-strain properties - Energy measurements - Stress softening - Tension set En ligne : https://drive.google.com/file/d/1jPADSPTY5-SNU-6jR_5P9svMruDo7w2M/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31863 [article]

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The chemistry of zirconium tannage / A. L. Hock in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 59, N° 6 (11-12/1975)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 59, N° 6 (11-12/1975) . - p. 181-188 Titre : The chemistry of zirconium tannage Type de document : texte imprimé Auteurs : A. L. Hock, Auteur Année de publication : 1975 Article en page(s) : p. 181-188 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Tannage au zirconium Tannage minéral Tannage dans lequel interviennent différents minéraux. Le plus répandu est le tannage aux sels de chrome, mais aussi à l’aluminium Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Zirconium tannage, i.e. the mechanism by which zirconium-containing ions present in acid aqueous tanning solutions of varying compositions and complexity react at pH values ranging from about 1 to 3 to form the pattern of cross-linkages which imparts to skins the properties associated with leather, is still far from being elucidated. One underlying reason is undoubtedly the present imperfect knowledge of the structure of collagen fibres themselves. The fibrils appear to consist of twined triple units of polypeptide chains of differing lengths, the repeating pattern of amino acid residues, joined together by peptide links being based roughly one-third on glycine, one-third on alanine plus other amino acids, and one-third on imino acids comprising about equal parts of proline and hydroxy-proline. The links which join the polypeptide chains together to form the triple chain structures are mostly hydrogen bonds, but there may also be some covalent bonds of the aldol type which are derived from the basic amino acid lysine in adjacent chains. It has also been shown that collagen chains have primary structures containing more amorphous regions, rich in polar amino acid residues (with acidic and basis ionising properties) and more crystalline regions rich in imino acid and non-polar amino acid residues. However, the present lack of a generally accepted explanation of zirconium tannage chemistry seems to be due at least as much to want of knowledge concerning the structure of the dissolved zirconium with which collagen combines at the moment that the tanning reaction takes place. This applies to published laboratory investigation of tannage chemistry as well as to conclusions based on more practical tannage. The complexity of aqueous zirconium chemistry, particularly that of the sulphate salts which prevail in the leather industry, has long been recognised. Attempts to rationalise the often conflicting published information were made before 1960, notably by Blumenthall, but it is fair to say that true appreciation of the complex structure of zirconium ions-and therefore their likely bonding characteristics-only began to be possible within the last 15 years or so. Better understanding of aqueous zirconium chemistry has corresponded with higher consumption of zirconium compounds by various industries and increased interest in the mechanisms of the reactions involved. Much of the published work has been done in USA and USSR. It was, of course, not available to the Somerville school, Lassère, Reed and co-workers, and others who pioneered zirconium tannage and have sought to explain its chemistry. The hydrolytic and polymerisation reactions of zirconium cations which take place spontaneously, or can be promoted, in zirconium oxychloride solutions and their effects on the structure of these ions were discussed by Clearfiels about ten years ago. He also speculated on the structure of zirconium ions in sulphate solutions. Zirconium oxychloride solutions have been recently investigated more fully by Rijnten. The aqueous chemistry of zirconium and the bonding between hydrous zirconium oxide and other substances in industries other than leather tannage were reviewed in 1974. Note de contenu : - Structure of zirconium ions - Review of theories of zirconium tannage - General comment - Older comment - Recent comment - Ranganathan and reed - Williams-wynn - Babich and shapilskaya En ligne : https://drive.google.com/file/d/1-9PtSYX_dNeYvKlQ2YH8KP5DaIl2_uD6/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31864 [article]

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