Thermal and dynamic mechanical analysis of bovine hide

Abstract

Dynamic mechanical and thermal analysis has been used to investigate the effects of chrome tanning on the viscoelastic properties of an indigenous Kenyan Boran bovine hide. It has been shown that this technique can be used to assess the effects of the leather-making processes on the final leather. From the results, each process of the leather making can be customized for certain application fields. For instance, tanning has shown to enhance the storage modulus (E′), shear stress (σ) and thermal stability at all frequencies and temperatures while decreases the loss modulus (E″), loss factor, viscosity (η) and shear strain (e). All the properties exhibited dispersion with two distinct frequency ranges: 0.1–30 and 30–100 Hz. The properties become less frequency dependent at frequencies higher than 30 Hz. Tanning enhances E″ at frequencies lower than 30 Hz but lowers E″ at higher frequency than 30 Hz. The dominant elastic nature of hides implies that the majority of the mechanical energy is dissipated by elastic deformation. The properties investigated showed an increase with temperature before drastic drops at specific temperatures. It can be noted that tanned hide stores more residue stress, and its molecular chains are easier to slide over each other when shearing forces are applied compared to pickled hide.