Al2O3/chitosan nanocomposite: Preparation, characterization and kinetic study of its thermal degradation

摘要

The 10%Al2O3/Chitosan nanocomposite (100%Al2O3/CS) was prepared and characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Brunauer, Emmett and Teller method (BET). These techniques showed the formation of 10%Al2O3/CS by the interaction between functional groups of CS such as -NH2,-OH and -CO- and Al2O3. The non-isothermal degradation process of 10%Al2O3/CS under an air atmosphere was investigated by Simultaneous ThermoGravimetric and Differential Thermal Analysis (TGA/DTA) and Differential Scanning Calorimetry (DSC) at different heating rates (beta = 5, 10, 15 and 20 K/min). The kinetic parameters of thermal degradation were calculated using KissingerAkahira-Sunose (KAS) and Kissinger (KIS) methods, and it was found that the average values of activation energies were E-a = (110 +/- 5) kJ/mol from Kissinger method, but the KIS method give three conversion domains in which E-a exhibits practically constant values, namely (0.15 - 0.30), (0.35 - 0.50) and (0.60 - 0.68) with average values of (131 +/- 3) kJ/mol, (190 +/- 10) kJ/mol and (71 +/- 7) kJ/mol, respectively. At last, the value of range (0.15 +/- 0.30) was used to match the experimental and simulated Y(alpha) and Z(alpha) master plots. Indeed, it was found that the modified Sestak-Berggren f (alpha) = c(1 - alpha)(n)alpha(m) does not correctly describe the kinetics of 10%Al2O3 gradation process, even if this model allowed reproducing qualitatively the Y(alpha) curves, giving the same maximums, alpha(m), for each value of beta in rang of alpha (0.15-0.3), which are consistent with the thermal degradation mechanisms of 100%Al2O3/CS. Finally, the estimated temperature of degradation is 565 K with a rate constant of 0.172 min(-1).