Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2006
Publication Date: 10/1/2006
Citation: Liu, C., Latona, N.P., Ashby, R.D., Ding, K. 2006. Environmental Effects on Chrome-free Leather. Journal of American Leather Chemists Association. 101(10):368-375. Interpretive Summary: Non-chrome-tanned leather, also known as chrome-free leather, has gradually gained commercial importance, particularly for automobile upholstery applications. However, the ability of leather to withstand degradation due to changes in environmental conditions is a very important automobile leather quality. The fast growth in the domestic production of automotive leather to meet the demands of automakers magnifies the significance of this quality. Our objective for this research is to understand how key environmental variables, such as temperature, UV radiation, and humidity affect leather properties. We derived a mathematical equation for predicting the relationship between the environmental variables and colorfastness, as well as the resultant physical properties. The mathematical model provided by this research could lead to a proper formulation of additives to apply to leather for improving the resistance of environmental changes. Moreover, the results obtained from this research may benefit the leather industry in better understanding the environmental effects on chrome-free leather, thereby tailoring their leather-making process to meet quality specifications.
Technical Abstract: Chrome-free leather has gradually gained commercial importance, particularly for automobile upholstery applications. However, in many respects, chrome-free leather is inferior to chrome-tanned leather. UV and heat are known to be more detrimental to chrome-free leather than chrome-tanned leather, especially when it concerns the colorfastness and mechanical properties. Temperature, UV radiation, and humidity are key environmental factors that affect leather properties. The role of humidity and its interaction with UV radiation and temperature on leather properties, however, are not clear to the leather industry, and this information is needed for formulate antioxidants that will protect chrome-free leather from UV and heat damage. Therefore, a systematic study was performed to formulate the relationship between these three environmental variables and resultant colorfastness and mechanical properties. A second order regression equation was derived to plot response surfaces that clearly illustrate the relationship between the environmental variables and colorfastness, as well as the resultant physical properties. Observations showed an intriguing interaction between humidity and radiation dose. Measurements revealed the colorfastness and tensile strength decreases as the humidity increases until UV radiation dose reaches over about 240 kJ/m2. Thereafter, the increase in humidity may actually lead to an improvement on both properties. Observation showed the stiffness will decrease steadily with an increased humidity, whereas the toughness index decreased. This study also used differential scanning calorimetry (DSC) to determine the denaturation temperature as a function of various environmental conditions. We observed a correlation between colorfastness and denaturation temperature.