Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2008
Publication Date: 4/1/2009
Citation: Liu, C., Liu, L.S., Latona, N.P., Goldberg, N.M., Cooke, P.H. 2009. Composite Drying with Simultaneous Vacuum and Toggling. Journal of American Leather Chemists Association. 104(4):131-138.
Interpretive Summary: Because of environmental and health concerns over the use and disposal of chrome-tanned leather, chrome-free leather has gradually gained commercial importance, particularly for automobile upholstery applications. The quality of chrome-free leather, however, is known to be inferior to that of chrome-tanned leather. ARS scientists developed a drying method using a combination of toggling and vacuum drying to improve the quality of chrome-fee leather. Vacuum drying offers fast speed and low temperature drying, which is particularly advantageous to heat-vulnerable chrome-free leathers. On the other hand, adding a toggle action during vacuum drying can significantly increase the area yield. ARS scientists have established optimal drying condition to achieve a 16% increase in area yield with good leather quality. Tanneries may use this research result to improve the quality of chrome-free leather, increase area yield and therefore better profits.
Technical Abstract: Drying is one of key steps to govern the physical properties of leather and it is where leather acquires its final texture, consistency and flexibility. Recently we have been working diligently to improve chrome-free leather by optimizing its drying process. We developed a drying method using a combination of toggle and vacuum drying together. This is because vacuum drying offers fast speed at a low temperature, which is particularly advantageous to heat-vulnerable chrome-free leathers. On the other hand, adding a toggle action during vacuum drying can significantly increase the area yield. We explored this composite drying method and investigated how drying variables affect mechanical properties and area yield of chrome-free leather. This study showed that the stretch applied in a drying operation significantly affects stiffness and area yield. We also observed that biaxial stretch increases tensile strength but has less effect on fracture energy. Our study also showed that tensile strength increases with apparent density and decreases with drying rate. Under an optimal drying condition, a 16% increase in area yield with good properties can be achieved.