Do Leather Anisotropic Properties have an Effect on Shrinkage Temperature?

Abstract

Herein are the results of studies of mechanical properties andshrinkage temperature of cowhide leather tanned with modifiedglutaraldehyde and chrome. The tests were carried out onsamples cut from both kinds of leather parallel and perpendicularto the backbone. The aim of these studies was determiningwhether the sample orientation to the backbone, thus leatheranisotropic properties defined by its tensile strength andultimate extension, has an effect on shrinkage temperature andkinetics of this process.echanical properties were tested according to PN-EN ISO3376:2012 Leather – Physical and mechanical tests –Determination of tensile strength and percentage extension. Theconditions for shrinkage temperature measurements were setaccording to guidelines specified in PN-EN ISO 3380:2015-11Leather – Physical and mechanical tests – Determination ofshrinkage temperature up to 100°C. The experiment was carriedout by using an instrument of our own design enabling automaticrecording of leather specimen length changes duringmeasurement.The results of mechanical tests allowed the determination of thedegree of differentiation of obtained tensile strength andultimate extension values depending on test sample orientationto the backbone. For leather tanned with modified glutaraldehydethe coefficient of variation with respect to tensile strength inboth directions was 0.31, while for chrome tanned leather was0.44. The coefficient of variation for ultimate extensioncalculated for both directions was 0.55 and 0.42 forglutaraldehyde and chrome tanned leathers, respectively.The slope of obtained regression lines was compared to find anystatistically significant differences in leather shrinkage ratedepending on orientation to the backbone. The results ofanalyses performed for two differently tanned leathers show nostatistically significant differences in shrinkage rate depending on cut orientation. Thus, anisotropy of mechanical properties ofleather samples under investigation does not affect bothshrinkage temperature and the rate of this process.