Investigating Effects of Sulphonated Synthetic Fatliquor Concentration on the Mechanical Properties of Cowhide Leather

Diverse applications of collagen-based materials such as leather have sparked research interest that seek to examine the effect of fatliqours on their mechanical properties. As the applications of these collagen materials increases such as in the field of medicine, footwear and upholstery, more studies are required to gain more insight on how their quality and durability can be improved. Leather being one of the collagen-based material is a by-product of the meat industry, made from animal hides and skins after undergoing processes such as pre-tanning, tanning, post-tanning, and finishing operations. These processes play a vital role in giving and preserving important leather properties. Although fatliqours have been noted to greatly affect the mechanical properties of leather, the effect of varying sulphonated synthetic fatliquor concentration on the mechanical properties of cowhide has not been investigated. Hence, this study examined the effect of varying concentrations of sulphonated synthetic fatliquor on the mechanical properties of cowhide leather. Lisuline Cufb, a sulphonated synthetic fatliquor was procured from ChemKleen Products Limited. The two wet blue pieces of leather procured from the Kenya Industrial Research and Development Institute (KIRD), were neutralized to the right PH. Then they were divided into five sheets, where four of the sheets were re-tanned using mimosa, while the remaining sheet not re-tanned acted as control for the experiment. The weight of five sheets was then measured using weighing balance one at a time. Four sheets that were retanned using mimosa were fatliquored with 5%, 10%, 20% and 25% with sulphonated synthetic fatliquor in a drum at 10 rpm for 3 hours while the remaining sheet was not retanned. For tensile strength and elongation, eight samples were cut in a dumb-shell shape, four along the backbone direction and the remaining four, were cut perpendicular to the backbone from each sheet while for tear strength, eight rectangular samples with a template hole were obtained from each sheet, four along the backbone direction and the remaining four were cut perpendicular to the backbone. For Dynamic Mechanical Analysis, rectangular samples of dimensions 30mm×9.33mm×0.93mm were obtained from each sheet and then subjected to dynamic mechanical analysis. The samples were then conditioned in a standard atmosphere of 23/50, temperature of 23±2 ⁰C, and humidity of 50±5% R.H. for 48 hours before testing. Results showed that tensile strength increased consistently where the value of control sample was 22.42 N/mm².The value increased from 26.06 N/mm² to 29.70 N/mm² and then 34.47 N/mm² as the concentration of fatliquor increased from 5% to 10% and then to 20% but at 25% the value dropped drastically to 26.33 N/mm². For percentage elongation the value for control sample was 19.2%, the value increased from 23.80% to 27.22% and then 31.40% as the concentration increased from 5% to 10%and then to 20% but dropped to 25.38% at 25% concentration. For tear strength, the value for control sample was 176.71N/mm, the value increased to 208.28N/mm then to 227.04N/mm and further to 237.89N/mm when fatliquored with 5%, 10% and 20% respectively. The value dropped drastically to 187.17N/mm at 25% concentration. Samples cut parallel to the backbone recorded higher tensile strength than those sampled perpendicular to the backbone. The values for percentage elongation and tear strength were higher in samples cut perpendicular to the backbone than those sampled parallel to the backbone. The values for storage compliance increased with an increase in concentration of sulphonated synthetic fatliquor and temperature each attaining different peak value at different temperatures, a drastic drop was noted for all samples after peak value. For loss compliance, the values decreased to about 180 ⁰C, before an increase at a temperature above 180 ⁰C. The results for tan delta increased with an increase in fatliqour concentration until they attained peak values at different temperatures, before a drastic drop as the value of temperature increased. In conclusion, Lisuline Cufb concentration affected the mechanical properties of cowhide leather.