Effects of Stress State while Dried on Leather Mechanical Properties

After being chrome tanned, the wet blue was retanned, neutralized, and fatliquored with Coripol MK to get different leather samples. Under the condition of ambient drying and vacuum drying, different forces were applied on above leather samples to provide different stress states, i.e., uniaxial stress state and biaxial stress state. The effect of different stress while dried on leather mechanical properties was investigated. Combined with the SEM results of grain and cross section, the change patterns were discussed. They indicate that after drying with stretching, the tensile strength and the stiffness of the samples are increased while the elongation at break is decreased. Compared with the sample being biaxial stress processed, the sample with a uniaxial stress process is higher in tensile strength and lower in elongation at break. After being dried and stretched, the grain smoothness of the sample becomes better. Uniaxial stretching increases the orientation degree of the collagen fiber in the sample, while biaxial stretching may separate the collagen fiber bundles. On the basis of the work, a simplified fiber structure model during stretching was proposed.