| Titre : |
The swelling of pelt at neutral pH as a result of the conditions of the previous pickle |
| Type de document : |
texte imprimé |
| Auteurs : |
M. Portavella, Auteur ; M. Soldevila, Auteur |
| Année de publication : |
1976 |
| Article en page(s) : |
p. 37-45 |
| Langues : |
Anglais (eng) |
| Catégories : |
Cuirs et peaux de moutons
Gonflement (physique)
Matériaux -- Epaisseur
pH
PicklageLe picklage consiste à faire absorber à la peau en tripe une quantité importante d'acide, en présence de sel neutre (NaCl) pour réprimer le gonflement que provoquerait l'acidité du milieu.
Température de retrait
Volumétrie (chimie analytique)
|
| Index. décimale : |
675 Technologie du cuir et de la fourrure |
| Résumé : |
Tanners who process pickled sheepskins which have benn stored for a long time have probaly noticed taht sometimes the pelts are liable to swell a great deal after having been returned to the pelts state (for example, after being depickled to pH 7, and thoroughly washed).
The published literature covering the deterioration produced on the skin by the preserving pickle does not refer to this swelling. There are many papers which deal with the attacks of acids (without salt) on collagen, and others which treat the acid pretreatment of collagen in order to obtain gelatin. Some of them mention that this king of acidic attack has also been observed in the presence of common salt, with the consequent swelling at neutral pH. The conditions which produce this swelling have not been studied systematically as yet.
In this paper, variations of both swelling at neutral pH and the shrinkage temperature of the pelts (Spanish sheepskins after a conventional beamhouse process) are investigated as a result of the conditions of the previous pickle (NaCl in the bath: 6 and 12°/Bé; H2SO4: 1.3 and 9% on pelt weight; temp.: 20 and 40°C and time 0, 1, 6, 8 and 34 days).
It has been found that both the degree of swelling and the decrease of shrinkage temperature depend on the conditions of the previous pickle. Both increase when the pickle action has been more intense.
Furthermore, the effects of the acidic attack produced by a strong pickle are studied specifically on: (a) variations in the percentage of swelling and shrinkage temperature at different pH values; (b) titration curves; (c) the amount of chrome taken up by the skin in a conventional tanning; and (d) physical tests of the leather obtained, measured in the Lastrometer.
Accordind to the results, and relating them to the fidings of other authors, some theoretical aspects of the possible causes of this swelling are discussed.
In conclusion, a simple method to assist the sheepskin tanner is presented. This method aids in establishing the degree of deterioration of the skins caused by the combined action of the beamhouse process and the preserving pickle. The method does not require specialised personnel or instrumments. |
| Note de contenu : |
- Fig. 1 : Precentage of swelling at neutral pH as a function of pickle and storage conditions
- Fig. 2 : Shrinkage temperature of pelts as a function of pickle and storage conditions
- Fig. 3 : Precentage of swelling at different pH values
- Fig. 4 : Shrinkage temperature as a function of pH. Measurements in Na2SO4 (13° Bé°) solution
- Fig. 5 : Titrage curves
- Table 1 : Swelling precentage and shrinkage temperature of pelts as a function of pickle and storage conditions
- Table 2 : Swelling precentage as a function of pH
- Table 3 : Shrinkage temperature as a function of pH
- Table 4 : Titrage curves data
- Table 5 : Shrinkage temperature and ash precentage oh the chrome tanned leathers
- Table 6 : Thickness and physical strenght (Lastometer) |
| En ligne : |
https://drive.google.com/file/d/1kVXgbu949t9Aq3hCSuO5dLUzBroZN8OU/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=31866 |
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 60, N° 2 (03-04/1976) . - p. 37-45
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