Kinetic study on solid state thermal degradation of epoxy nanocomposite containing Octasilane polyhedral oligomeric silsesquioxane

A nanocomposite based on epoxy and octasilane polyhedral oligomeric silsesquioxanes (Octasilane POSS) was synthesized and characterized. Thermal degradation kinetics of the epoxy system containing different concentrations of Octasilane POSS was studied by thermogravimetry analysis (TGA). The derivative thermogravimetry (DTG) curves showed a single stage decomposition process. Influence of both the Octasilane POSS concentration and heating rate on degradation characteristics was eliminated. The better thermal and morphological properties were obtained using a formulation containing 1 wt.% of Octasilane POSS. Using Kissinger's method, activation energy of the degradation process was determined to be 155.8 kJ/mol. This is in good agreement with that value determined by Flynn–Wall–Ozawa isoconversional approach. Based on 13 various model functions and the calculation procedures of Coats–Redfern, Van Krevelen, Horowits–Metzeger, and Criado et al. methods the degradation mechanism was found. It was concluded that the kinetics of thermal degradation obeys through a nucleation and growth mechanism described by Avrami–Erofeev equation (A2). The homogeneous dispersion of Octasilane POSS in the polymer matrix was evidenced by SEM and XRD observations.

► Presence of Octasilane POSS at low wt.% results in Tg improvement.
► The best degradation kinetic model was found to be A2 model.
► The nanocomposite showed a homogeneous amorphous morphology.