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 directly incorporated into the base polymer can be employed to protect polymeric materials against attack by fire. Nowadays, novel nanomaterials including polyhedral oligonneric silsesquioxane (POSS) are employed to impart potential flame retardation characteristics to polymers, which open up new ways to prepare flame retarded materials. In this work, octaphenyl polyhedral oligomeric silsesquioxane (ph-POSS) and its bromide derivative (Br.ph-POSS) were used as novel fillers for polystyrene and the differences in their enhanced combustion properties were investigated and discussed. The microstructures of composites were characterized by TEM, which indicated that POSS nanoparticles were dispersed in the base polymer homogeneously and the amount of fillers were gradually increased with higher amount of POSS. The combustion behaviour of the composites was tested by cone calorimetry, which showed that their flame retardant properties were also greatly improved by increased amounts of POSS fillers. Nevertheless, there are some differences in the combustion properties 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 in slower smoke production rate (SPR) and rather bigger drops in peak values of CO release rate (CORR) and CO concentration (COO) during the combustion test (the largest relative decline in peak values of CORR and COC were 81.8% and 84.3%, respectively). These improvements are attributed to the homogenously dispersed POSS nanoparticles and related Br-Sb synergistic effects, while the differences are due to the presence of different substituents and/or elements in dissimilar POSS cages.