Abstract

Artificial acid rain was chosen to simulate the influences of gaseous pollutants on vegetable-tanned leather. The vegetable-tanned leather samples were soaked in the artificial acid rain for 0, 5, 10, 15, 20 and 25 days, at 50°C and 100% relative humidity conditions. Then, these samples were evaluated by various analytical methods. Micro hot table (MHT), differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to evaluate the influences of acid rain on thermal behaviours. Damage to mechanical properties were also analyzed by a standard method. Fourier transform infrared spectroscopy (FTIR) and optical microscopy were used to investigate the changes of structural and histological properties during ageing.With the extension of ageing time, thermal stability was gradually reduced to lower values, including shrinkage temperature, thermal denaturing temperature, associated enthalpy and temperature of maximum decomposition rate. In addition, mechanical properties such as tensile strength, tear strength and elongation at break also gradually decreased. The FTIR results showed that, during the ageing process, the amide I and amide II bands of collagen were gradually shifted to lower numbers, indicating increasingly serious damage to the structure of the peptide chain corresponding to obvious fibril breakages which were also detected through optical microscopy.