Submitted to: Journal of Materials Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/17/2002
Publication Date: N/A
Interpretive Summary: Fatliquoring is one of the critical steps in the leather-making process, wherein lubricants (so-called fatliquor) are added to prevent the leather fibers from sticking together. This process reduces friction between the fibers and promotes the mobility of the fibers, thereby providing sufficient pliability to the leather. Acoustic emission (AE) technology employs "listening" to and analyzing the sounds emitted by a material as i is stretched. As part of our efforts to investigate the applications of AE technology to leather manufacture, we have examined the feasibility of using AE to measure the degree of lubrication of leather produced with various concentrations of fatliquor. We discovered an excellent correlation exists between the degree of lubrication of leather and the patterns of acoustic activities, measured by an AE analyzer, as leather samples are stretched. The results of this work may provide a route to monitor the degree of lubrication of leather, which until now has been essentially unmeasurable. By using the AE method developed from this work, the leather industry may easily adjust its fatliquoring conditions to produce high quality leather.
Technical Abstract: For thousands of years, collagen materials, such as leather, have been among the most dominant natural fibrous materials used by humans. Fatliquoring is one of the critical steps in the leather-making process, wherein oil or a lubricant is added to the leather to prevent the leather fibers from sticking together, thereby providing sufficient pliability to the leather. We have examined the feasibility of using the acoustic emission (AE) technique to characterize the degree of lubrication of leather produced with various fatliquor concentrations. In a tensile test, an acoustic transducer was contacted with the leather samples to collect their AE quantities and properties. The samples lubricated with a fatliquor concentration less than 10% showed twin peaks on the plot of hits rate versus time. This implied that a non-uniform fracture occurred in a poorly lubricated leather structure. In contrast, a sufficiently lubricated leather structure showed a steady increase in hits rate with time until it fractured. Traditional stress-strain tests did not reflect these behaviors. Observations also showed a direct correlation between the cumulative hits and fatliquor concentration. The results of this work may provide a route to identify an adequate degree of lubrication in the leather.