EFFECT OF SKIN TYPE AND DIRECTION OF APPLIED FORCE ON PEEL STRENGTH OF SKIN LAYERS

Cohesive peel strengths of goat, ovine and bovine leathers have been d etermined by measuring the peel strength at 90-degrees of leather-rigi d polyvinylchloride joints which were bonded with a polyurethane adhes ive. Differences in cohesion between different zones of each leather, as well as between the different directions and senses in which peel t ests were carried out, showed up in all the leathers except ovine leat her. The quantitative differences in peel strength can be attributed t o the structural characteristics of each leather, and especially to th e arrangement of the collagen fibres in the grain layer. Thus the bell y and shoulder zones had the best cohesive properties. On the other ha nd, the consistency of the grain layer was smaller than that of the co rium layer, which had the strongest cohesion. Therefore in order to ac hieve sufficient adhesion in shoe making for example it is necessary t o eliminate, by roughing, successive layers until the grain-corium int erface is reached.