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Lime-free unhairing : Part 2 / Virgilijus Valeika in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 82, N° 3 (05-06/1998)
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Titre : Lime-free unhairing : Part 2 : Influence of added salts on NaOH unhairing and on hide properties Type de document : texte imprimé Auteurs : Virgilijus Valeika, Auteur ; J. Balciuniene, Auteur ; Kestutis Beleska, Auteur ; A. Skrodenis, Auteur ; V. Valeikienè, Auteur Année de publication : 1998 Article en page(s) : p. 95-98 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The influence of the system containing NaOH, Na2S and a salt such as NaCl, Na2SO4, HCOONa or Na2HPO4 on the properties of pelt in the unhairing process was investigated.
The process of unhairing was separated into two stages : (i) degradation of the hair and (ii) opening up the dermal structure. The opening up stage was carried out in the liquor from the hair degradation after dilution with water.
It was established that the above salts added to the solution for opening up the dermal structure influence the kinetics of the removed collagen and non-collagen proteins and also swelling of the hide. The supplementary use of salts is not convenient because it is more convenient to regulate the properties of the pelt by using a suitable quantity of water in the opening up the stage.
The technology of lime-free production of pelt was developed based on the results of these investigations. Application of this technology of lime-free production of pelt was developed based on the results of these investigations. Application of this technology showed that the quality indexes of the garment leather produced using this method meet the manufacturer's requirements.Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7901
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 82, N° 3 (05-06/1998) . - p. 95-98[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 007022 - Périodique Bibliothèque principale Documentaires Disponible Lime-free unhairing : part 4 : Influence of unhairing method on dermatan sulphate and microscopical investigation of pelt and leather / E. Kazlauskaite in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 86, N° 2 (03-04/2002)
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Titre : Lime-free unhairing : part 4 : Influence of unhairing method on dermatan sulphate and microscopical investigation of pelt and leather Type de document : texte imprimé Auteurs : E. Kazlauskaite, Auteur ; J. Balciuniene, Auteur ; A. Zaliauskiene, Auteur ; Kestutis Beleska, Auteur ; Virgilijus Valeika, Auteur ; V. Valeikienè, Auteur Année de publication : 2002 Article en page(s) : p. 59-64 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cuirs et peaux -- Analyse
Epilage
Microscopie
Sulfate de dermataneIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : The article presents the final research into the system containing NaOH, Na2S, and a salt such as NaCl, Na2SO4 or Na2HPO4 and their influence on the properties of pelt and leather. Here are two main pointsof the investigations : the establishment of dermatan sulphate changes during unhairing and the microscopy investigation.
It was established that the unhairing method influences the amount of dermatan sulphate in pelt. The method for dermatan sulphate determination was developed and used in this research. The results show that a strongly alkaline action does not increase the removal of dermatan sulphate.
As collagen’s chemical and physical changes could be reflected in its structure, optical and scanning electron microscopy analyses of pelt and leather grain and corium were carried out. The micrographs show that the structure of pelt and leather depends on the unhairing method and it differs-differences in opening-up level are observed. These differences are clearly visible and depend on the method of unhairing. The microscopy images confirm the importance of the role of salts, which are added to the unhairing system NaOH+Na2S.Note de contenu : - Improvement of dermatan sulphate determination
- Investigation of dermatan sulphate in lime-free unhaired pelt
- Grain microscopy
- Microscopy of corium
- Table 1 : Influence of unhairing method on degradation of collagen and dermatan sulphateEn ligne : https://drive.google.com/file/d/14f4WrHFHAsQIcAbi4fhaayMRoSR3Nr8c/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=40029
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 86, N° 2 (03-04/2002) . - p. 59-64[article]Lime-free unhairing : Part 5. Some peculiarities of dyeing lime-free leather / A. Zaliauskiene in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 90, N° 2 (03-04/2006)
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Titre : Lime-free unhairing : Part 5. Some peculiarities of dyeing lime-free leather Type de document : texte imprimé Auteurs : A. Zaliauskiene, Auteur ; Kestutis Beleska, Auteur ; Virgilijus Valeika, Auteur ; J. Balciuniene, Auteur ; V. Valeikene, Auteur ; V. Tricys, Auteur Année de publication : 2006 Article en page(s) : p. 73-79 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Coefficient de diffusion Un coefficient de diffusion est une grandeur caractéristique du phénomène de diffusion de la matière. Le coefficient de diffusion mesure le rapport entre le flux molaire dû à la diffusion moléculaire, et le gradient de concentration de l'espèce chimique considérée (ou, plus généralement, de la variable d'effort entraînant cette diffusion), comme formulé par la loi de Fick.
Colorants
Cuirs et peaux -- Teinture
Hydrophobie
Pénétration (physique)
Rouge (couleur)
ThermodynamiqueIndex. décimale : 675 Technologie du cuir et de la fourrure Résumé : The interaction of leather, prepared by the lime-free method, and a series of 1:2 metal complex dyes has been investigated by determining the distribution of the dyes at equilibrium. Kinetic and thermodynamic aspects such as the rate of dyeing, heat of dyeing, entropy, affinity of dyes on the lime-free and conventional leather have been studied. The diffusion coefficient was calculated by means of the Weisz pore and Krenk models.
It has been established that the sorption isotherms for these dyes on both types of leather fibres show a Langmuir type of behaviour. The dyeing system hydrophobic C.I. Acid Red 247/lime-free leather has a positive heat of dyeing: dyeing is an endothermic process in this case.
The change of entropy of interaction of hydrophobic C.I. Acid Red 247 and leather fibres is 24 cal/mol•K. An increased degree of freedom should be associated with water molecules such as those hydrating the dye and the fibre, and possibly, due to randomness in the fibre itself. This decreased degree of the order of water molecules results in a positive change of entropy, which then is the thermodynamic cause of the hydrophobic bonding.
The influence of factors such as, initial amount of dye, pH of leather and temperature on the dyeing process was established. The results have shown that lime-free leather absorbs lesser amounts of dye during dyeing but that, the dye penetrates more deeply compared with conventional leather. The amount of dye, pH and temperature has no influence on such a tendency.
On the other hand, the investigation has shown that the factors mentioned have a more marked influence on the progress of dyeing of lime-free leather compared with dyeing conventional leather. This means that inconsiderable deviation from determined parameters of dyeing can markedly deteriorate the quality of the dyed leather.
The data obtained have confirmed that the change in the method of liming considerably influences subsequent processes in leather processing.Note de contenu : - EXPERIMENTAL PROCEDURE : Leather samples for dyeing - The preparation of leather fibres for dyeing - Dyes and dyeing - Determination of hydrophobicity of dyes - Determination of depth of dye penetration into leather - Investigation of dyeing kinetics - Thermodynamic investigation of dyeing
- RESULTS AND DISCUSSION : Kinetic and thermodynamic investigation - Investigation of dyeing parameters on the progress of dyeing
- Table 1 : Indexes of pelt and leather obtained by use of lime-free and conventional unhairing
- Table 2 : The dependence of diffusion coeffficient on unhairing method
- Table 3 : The thermodynamic characteristic of dyeing processEn ligne : https://drive.google.com/file/d/16mWq3L-c0sNpayWDNSSXPgzVTvU4htbU/view?usp=share [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39160
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 90, N° 2 (03-04/2006) . - p. 73-79[article]Use of NaOH for unhairing hides and the influence of the addition of salts on the process and on the hide properties / Virgilijus Valeika in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 81, N° 2 (03-04/1997)
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Titre : Use of NaOH for unhairing hides and the influence of the addition of salts on the process and on the hide properties Type de document : texte imprimé Auteurs : Virgilijus Valeika, Auteur ; J. Balciuniene, Auteur ; Kestutis Beleska ; A. Skrodenis ; V. Valeikienè Année de publication : 1997 Article en page(s) : p. 65-69 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The influence of the system containing NaOH, Na2S and a salt such as NaCl, Na2SO4, HCOONa or Na2HPO4 on the properties of hair in the process of unhairing was investigated. The influence of alkaline process conditions such as concentration of NaOH and salt, temperature and duration of the process on the degradation of collagen and non-collagen proteins, the swelling and the quality of unhairing was also studied.
It was established that addition of various salts influences the degree of opening up of the dermal structure. This is observed when the amounts of additional salts are not less than 4-5 % of NaCl, Na2SO4, HCOONa and 1-2 % of Na2HPO4. The unhairing efficiency decreased when these amounts of salts were used with the exception of NaCl. The temperature is of great importance. It must be no more than 30°C. The tendency towards swelling does not follow the tendency to destruction of the collagen. Under certain conditions of the alkaline treatment, the swelling decreases and degradation of collagen increases.
The addition of various salts during alkaline treatment widens the range of possibilities of using NaOH for unhairing hides.En ligne : https://drive.google.com/file/d/1BfVgJjT0zJ7Xeo0SuMWdQWAc6-xDDgzj/view?usp=share [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8054
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 81, N° 2 (03-04/1997) . - p. 65-69[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 007015 - Périodique Bibliothèque principale Documentaires Disponible