Structural Characterization, Thermal Stability and Non-Isothermal Kinetic Analysis of Decomposition of Poly(methylmethacrylate) and Titanium Dioxide Nanocomposites

Abstract

In this study poly(methylmethacrylate) (PMMA) and the corresponding nanocomposites loaded with titanium dioxide (TiO2) films were prepared by a solution casting method. All materials were characterized by Fourier transform infrared spectroscopy, UV-visible spectroscopy, X-ray diffraction and scanning electron microscopy. The thermal properties were investigated by differential scanning calorimetry and thermogravimetric analysis. The results showed that the incorporation of TiO2 nanoparticles in PMMA decreased the thermal stability of the polymer. Moreover, the kinetic study of the thermal degradation showed that the apparent activation energies of the nanocomposites PMMA/TiO2 were lower compared to the pure PMMA, confirming the catalytic effect of TiO2 nanoparticles on the PMMA thermal decomposition. Furthermore, g(α), which is the integral form of the reaction mechanism function, showed that the degradation mechanism of the PMMA nanocomposites was strongly dependent on the TiO2 amount introduced into their matrices. Finally, the degradation mechanism of the pure PMMA obeyed the R3 model corresponding to a phase boundary reaction (n = 3), whereas in the case of the PMMA/TiO2 nanocomposites, they obeyed the R2 model, corresponding to a phase boundary reaction (n = 2), for PMMA/TiO2 (3%) and an A1.5 model, corresponding to an Avrami-Erofeev correlation (m = 1.5), was obtained for the remaining nanocomposites PMMA/TiO2 (5, 7 and 10%).