Thermal Stability and Degradation Kinetics of Poly(Methyl Methacrylate)/Sepiolite Nanocomposites by Direct Melt Compounding

Abstract

Poly(methyl methacrylate) (PMMA) nanocomposites based on sepiolite modified with trimethyl hydrogenated tallow amine by an adsorption process were prepared by melt compounding using a corotating twin screw extruder. The morphology and dispersion of sepiolite in the PMMA were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal stability and the activation energies were investigated by thermogravimetric analysis/differential thermogravimetric (TGA/DTG). The XRD and TEM results show that the sepiolite was dispersed homogeneously in the PMMA matrix at a nanometer scale. The TGA analysis revealed that the addition of sepiolite improved the thermal stability of PMMA. The apparent activation energies were calculated by the method of Flynn–Wall–Ozawa in nitrogen at four different heating rates, showing that sepiolite increased the apparent activation energies by about 20 kJ/mol within the degree of conversion (α) of 0.35–0.9, as compared with the reference PMMA sample.