Influence of retanning on the adsortion capacity on water on cattlehide collagen fibers

There are plenty of hydrophilic groups in the collagen fibers in leathers. Because the affinity between these hydrophilic groups and water molecules varies with environmental changes in temperature and relative humidity, leathers will adsorb or de-adsorb water in the environment if the environmental factors change. The strength, permeability, and thermal stability of leathers may be greatly affected by the water within them. Retanning is a key operation in leather making. The main purpose of retanning is to get leathers with some special performances. The water content in leathers is around 20wt%, an amount that cannot be neglected. However, no reports are found on the interactions between collagen and water, particularly the influence of retanning on the interaction between water and collagen fibers. The state that water molecules exist in collagen fibers, the mechanism for collagen fibers to adsorb water, the de-adsorption kinetics for water molecules to escape from collagen fibers, and the influence of retanning on the adsorption of water on collagen fibers should be made clear to improve the leathermaking technology by controlling the structure and behaviors of leathers.