Artificial deterioration of vegetable-tanned leather under synergistic effect of temperature and humidity

Abstract

• The synergistic effect of temperature and relative humidity on the deterioration of mimosa-tanned leather was investigated. • The changes in structure and thermal properties of artificially aged mimosa-tanned leather were systematically studied. • The TG-FTIR technique was employed to analyze the deterioration with the evolved gaseous products during thermal degradation. The deterioration of mimosa-tanned leather artificially aged at 80 °C and 60% relative humidity (RH) for up to 32 days was investigated. The changes in thermal properties, morphology, and structure were analyzed by thermogravimetric analyzer (TGA), polarized light microscopy (PLM), scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and X-ray diffraction (XRD). The results showed that the mimosa-tanned leather was deteriorated with a decrease in hydroxyproline content. After the artificial aging treatment, the thermal resistance of the mimosa-tanned leather was reduced. This result was further confirmed by PLM observations that the shrinkage temperature of the collagen fibers decreased with increasing aging time. The evolved gaseous products from the TGA were detected by TGA-FTIR to characterize the deterioration caused by aging. After aging, the evolution yield of nitrogen-containing products such as NH 3 , HNCO, and pyrrole decreased, while the evolution yield of CO 2 increased. According to the ATR-FTIR, XRD, and SEM results, the orientation and structural integrity of the collagen fibers were destroyed by artificial aging.