| Titre : |
Assessment of the thermal resistance of leather |
| Type de document : |
texte imprimé |
| Auteurs : |
Anna Matz ; Czeslaw Krawiecki, Auteur ; Miroslaw Mrozowski, Auteur |
| Année de publication : |
1984 |
| Article en page(s) : |
p. 1-7 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Contraintes thermiques
Cuirs et peaux -- Propriétés thermiques
Evaluation
Résistance thermique
|
| Index. décimale : |
675 Technologie du cuir et de la fourrure |
| Résumé : |
A great deal of attention has been paid recently to leathers designed for production of protective clothing worn under "hot" conditions. Several tanning technologies and methods for assessing leather properties have been developed. Relatively few papers have appeared which discussed the phenomena occurring in leather under the influence of heat in an air-dry medium. The practical measure of the leather thermal resistance, which cannot be overlooked in its assessment, is the temperature at which the visible deformation of leather occurs. Depending on conditions in which the leather remains while heated, we may differentiate between
(a) the autonomous deformation occurring under the influence of leather-free shrinkage and
(b) the deformation under the influence of stresses in leather.
The first case of deformation occurs in leathers of small area used in a loose state. Macromolecules, under the influence of heating in such samples, are subjected only to small internal stresses. When affected by a given thermal energy they may increase their entropy and assume the most thermodynamically advantageous shape at a given degree of their crossilinkage. On a macroscale this appears as a certain shrinkage of material.
In the case of leathers of greater area or of those used for products with more rigid construction, e.g. footwear, the shrinkage proceeds under slightly different conditions. On a macroscale, the shrinkage does not occur freely as a result of immobilisation of leather edges. On a microscale, the macromolecules have a limited possibil¬ity of changing their shape for they are interconnected by cross-linking. Considering this fact, there tends to be a maximum entanglement of chains, under given conditions, the stresses within the leather being higher the greater the number of macromolecules orientated towards the tested direction which participate in this phenomenon. An outer stress applied to the specimen influences the shrinkage rate and the temperature at which intensive shrinkage begins. The effect of temperature on leathers, under isometric conditions, is a limiting example of the shrinkage to stress ratio.
The purpose of our work was to evaluate the thermal resistance of leathers heated in an air-dry medium. The behaviour of leathers heated under free and isometric conditions has been investigated. |
| Note de contenu : |
- Conditions of test
- Examination of thermal resistance of leathers deformed under free conditions
- examination of the thermal resistance of leathers undergoing deformation in a stressed state
- Cyclic heating cooling of specimens
- Changes in leather subjected to constant temperature |
| En ligne : |
https://drive.google.com/file/d/1xc3X6iSqmmDPSKw6kXXdfr6G8kuHGcbu/view?usp=drive [...] |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34141 |
in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 68 (Année 1984) . - p. 1-7
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Les contraintes d'origines thermique / Paris : Dunod (1967)
