Abstract

We have constructed a model of air permeability taking into account appropriate parameters. Two of the parameters which represent the capillary radius and the amount of capillaries in a definite area of leather, respectively r and n have been deduced.

Researches on the locational differences in air permeability based on the model, show that different locations of leather have different values for r and n. The capillary radius of samples near the head location ranges from 452.9nm to 479.1nm, while the quantity of capillaries in the same sample is the greatest, from 7.948 x 1011/m2 to 8.617 x 1011/m2. The capillary radius (r) of a sample from a near centre location is the largest at 581.0nm and the capillary amount (n) is the lowest at only 5.262 x 1011/m2. The capillary radii of samples near the tail and centre of the leather are about 530nm.

Neither the thickness nor aperture ratio can successfully represent the air permeability of leathers. The air permeability process is rather complex. Using only the capillary radius (r) or the quantity of capillaries in a definite area (n) does not allow us to express the air permeability adequately.