Collagen structure and strength in leather

Strength is an important property of leather. However the structural basis of strength in leather is not well understood. We have used synchrotron based small angle X-ray scattering to investigate the structure and strength of collagen materials under a variety of conditions. This enables changes in the extent of orientation of the collagen fibrils to be quantified and the internal stress on the individual collagen fibrils to be measured. We have found that collagen alignment in the plane of the leather correlates strongly with strength in bovine and ovine leather and across a range of other mammals. Strong leather is better able to distribute applied stress across the full thickness of leather than weak leather. Collagen fibril diameter has a slight correlation with strength in bovine leather. Changes in thickness and dryness during processing affect fibril orientation. Fat liquor modifies the structure of the collagen in a systematic way but lubricates at a structural level above the fibril size. These factors provide a better understanding at the nanostructural level of strength in leather.