Kinetics of degradation and thermal behaviour of branched hepta phenyl POSS/PS nanocomposites

The thermal behaviour of Polystyrene (PS) based nanocomposites, loaded with different percentage of a novel Polyhedral Oligomeric Silsesquioxane (POSS) of general formula R7R′(SiO1.5)8, where R = phenyl and R′ = (CH2)9CH3, was studied in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Nanocomposites were prepared by in situ polymerization of styrene, in the presence of the appropriate POSS, and were characterized by Differential Scanning Calorimetry (DSC), to determine glass transition temperature (Tg), and by FTIR and 1H NMR spectroscopy, to verify and quantify the filler content into the polymeric matrix. Degradations were carried out into a thermobalance at various heating rates in the 25-700 °C temperature range. The characteristic parameters of thermal stability, namely temperature at 5% mass loss (T5%) and the activation energy (Ea) of degradation, were determined. The data obtained were then compared with each other and with those obtained in the past by our group on the mutual alkyl-POSSs/PS nanocomposites to verify the influence of the vertices of POSS cage on the compatibility with the polymeric matrix and on the thermal stability of the synthesized materials.