Study On The Aggregation Structure And Thermal Stability Of Collagen Fibers

In this paper, systematic studies were done on the influence of tanning, retanning, fatliquoring and humidity content on the mechanical performance, dry heat resistance and permeability of leathers. Such methods as X-ray diffraction, differential scanning calorimetry (DSC) were employed in the analysis of the aggregation structure of leather collagen fibers and its influencing factors. The results indicate that there are two phases in the leather collagen fibers, which are ordered structure (crystalline region) and disordered structure (amorphous region). The dimension of the ordered structure is about 2 nm, which proved that the "nuclear-shell structure" of the leather collagen fibers is reasonable. When leathers are tanned, their dry heat resistance, aperture ratio and water vapor permeability increase, while the tensile modulus, water absorption and crystallinity of leathers decrease. The dry heat resistance of leather collagen fibers increases, and the crystallinity decreases after being retanned. The homogeneity of leathers is increased after being retanned. After being fatliquored, the leathers show decreased dry heat resistance, aperture ratio, water vapor permeability and crystallinity, but the water absorption and elongation at break increase. The triple helix structure showed no change after such processes as tanning, retanning and fatliqoring. The dry heat resistance decreases and the crystalline region increases with the increase of the humidity content of the leathers.In this paper, the thermal degradation behavior of retanned and fatliquored samples are studied by thermogravimetry. The thermal degradation activation energies of these samples are obtained. The results indicate that, for both processes of retanning and fatliquoring, the thermal degradation activation energies are decreased. The reason may be that the hydrogen bonds between collagen fibers are broken in the two processes. The influence of atmosphere on the thermal degradation behavior and thermal degradation activation energy of untanned collagen fibers are discussed. The results indicate that, the thermal degradation is easier to happen in air atmosphere,...