Preparation, Characterization and Properties of Polystyrene Composites Using Octaphenyl Polyhedral Oligomeric Silsesquioxane and Its Bromide Derivative

Many additives, e.g., flame retardants and/or appropriate nanoparticles directlyincorporated into the base polymer can be employed to protect polymericmaterials against attack by fire. Nowadays, novel nanomaterials including polyhedraloligomeric silsesquioxane (POSS) are employed to impart potential flameretardation characteristics to polymers, which open up new ways to prepare flameretarded materials. In this work, octaphenyl polyhedral oligomeric silsesquioxane(ph-POSS) and its bromide derivative (Br.ph-POSS) were used as novel fillers for polystyreneand the differences in their enhanced combustion properties were investigatedand discussed. The microstructures of composites were characterized by TEM, whichindicated that POSS nanoparticles were dispersed in the base polymer homogeneouslyand the amount of fillers were gradually increased with higher amount of POSS. Thecombustion behaviour of the composites was tested by cone calorimetry, whichshowed that their flame retardant properties were also greatly improved by increasedamounts of POSS fillers. Nevertheless, there are some differences in the combustionproperties of the composites which are due to different kinds of POSS nanoparticles,i.e., Br.ph-POSS system was more effective in reducing the peak heat release rate(pHRR) (the largest relative decline in pHRR was 84.2%), while ph-POSS resulted inslower smoke production rate (SPR) and rather bigger drops in peak values of COrelease rate (CORR) and CO concentration (COC) during the combustion test (thelargest relative decline in peak values of CORR and COC were 81.8% and 84.3%,respectively). These improvements are attributed to the homogenously dispersedPOSS nanoparticles and related Br-Sb synergistic effects, while the differences are dueto the presence of different substituents and/or elements in dissimilar POSS cages.