Sodium montmorillonite effect on the morphology, thermal, flame retardant and mechanical properties of semi-finished leather

In the present work, the effect of sodium montmorillonite (Na+Mt) on the resulting properties of semi-finished (crust) leather has been thoroughly studied. Na+Mt has been added during retanning process of tanned (wet-blue) leather in specific conditions. The morphological analysis by scanning electron microscopy has pointed out that Na+Mt particles are homogeneously distributed and finely dispersed within the leather structure. The presence of clay mineral has affected the thermal stability of leather in nitrogen and air (assessed by thermogravimetry), as well. According to the sixty second vertical flammability test results Na+Mt particles have significantly reduced the burning length of the semi-finished leather. A barrier mechanism of the Na+Mt during combustion process is proposed. Mechanical properties (namely, tensile and tear strength) have proven to be considerably improved by using 1 and 3 mass% of Na+Mt; these results have clearly indicated the reinforcing effect of clay mineral platelets that somehow physically interact with leather.