Fundamental study of cross-linking of collagen with chrome tanning agents in traditional and Cr.AB processes

Transformation of animal skins into leather is a complicated mechanical and chemical process during which a significant amount of waste may be generat ed. Over the past few years the chemical and leather industries have made a great effort to develop products and processes that enable leather manufac turers to minimize their environmental impact. This improvement is the resu lt of fundamental research on leather. Even though during the past fifty years there have been numerous investigat ions on the chrome-tanning process, the mechanisms involved are not complet ely understood. The observations and data to be presented in this paper sug gest a possibility for one mechanism involved in chrome tanning. This paper presents a comparative study of three different chrome tanning processes u sing analytical techniques such as Fourier transform infrared spectroscopy, X-ray analysis and transmission electron microscopy. Results show that chr ome tanning is both an inter and intrafibrillar reaction. We also defined a new interesting parameter related to the chrome-tanning efficiency, the re ticulation coefficient CR.