Thermal degradation of hepta cyclopentyl, mono phenyl-polyhedral oligomeric silsesquioxane (hcp-POSS)/polystyrene (PS) nanocomposites

The thermal degradation of three Polyhedral Oligomeric Silsesquioxane/Polystyrene (POSS/PS) nanocomposites of formula R7 R′1 (SiO1.5)8/PS (where R = Cyclopentyl and R′ = Phenyl), at various (3%, 5% and 10%) POSS concentration, was studied in both inert (flowing nitrogen) and oxidative (static air) atmospheres. Compounds were prepared by the polymerization of styrene in the presence of POSS. Degradation was carried out in a thermobalance, in the scanning mode, at various heating rates, and the obtained thermogravimetric (TG) curves are discussed and interpreted. The temperature at 5% mass loss (T5%) and the activation energy (Ea) of degradation of various nanocomposites were determined and compared with each other and with those of unfilled polystyrene (PS). The T5% and degradation Ea values of nanocomposites were higher than those of neat PS, thus indicating a better heat resistance and lower degradation rate, and then a better overall thermal stability. On the basis of the obtained thermal parameters the nanocomposite at 5% of molecular filler appears the most thermally stable. The results are also compared with literature data on similar PS based nanocomposites.