Characteristics of leather tanned with nano-sio2

A nano-precusor which can, in-situ, produce nano-SiO2 under particular triggering condition was introduced into leather to improve the hydrothermal stability. In order to elucidate the reaction of nano-SiO 2 with protein and how it influences the properties of the protein, collagen was used as a model in a detailed investigation. The results from FTIR (Infrared) indicated that two new chemical bonds arose during the formation of the organic-inorganic nano-hybrid. One appears to be the reaction between nano-SiO2 formed in-situ by the hydrolysis of tetraethoxy silane and the -C=N-groups of arginine, histidine, and tryptophane in the backbone of collagen. In a second bond, occurring at the same time as the condensation of silanol proceeds, the pendent hydroxyl groups of collagen may partly react with Si-OH and form a strong interaction between the organic and inorganic phases. These two chemical bonds seem to contribute to the leather's high hydrothermal stability. The size distribution of nano-SiO2 as determined by Atomic Force Microscopy is approximately 50-80 nm and there appeared to be no agglomeration. Organic-inorganic nano-hybrid can improve the hydrolysis stability of collagen efficiently in the presence of enzyme, acid, and alkali. When the bated pelt is treated with 0.3 wt % nano-SiO2 (based on bated pelt weight), the shrinkage temperature reached above 95°C. Although the mechanical properties of nano-SiO2 tanned leather are inferior to chromium tanned leather, other properties of nano-SiO2 tanned leather, such as yield, grain, fullness and softness together with washability are all superior to chromium tanned leather.