Combustion and thermal properties of OctaTMA-POSS/PS composites

Inorganic–organic composites of octa(tetramethylammonium) polyhedral oligomeric silsesquioxanes (OctaTMA-POSS) and polystyrene (PS) were prepared by melt-mixing method. The composites were characterized by Fourier-transform infrared spectrometry (FT-IR), Transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), and thermal gravimetric analysis (TGA). Their flammability was evaluated by cone calorimeter test. The experimental results indicate that OctaTMA-POSS, when present in low ratios (1%–5%, weight ratio) in the composites, can decrease the peak heat release rate (HRR) by 15%, while high ratios of OctaTMA-POSS (20% and 30%) can decrease the peak HRR and the average HRR approximately linearly. Concentration and release rate of carbon monoxide (CO) in the composites combustion are also decreased evidently. Thermal gravimetric analysis under nitrogen and air atmosphere both show that the char yield increases obviously. These advances are attributed to the special properties of OctaTMA-POSS and its dispersion in PS.