Flame-retarded polystyrene with phosphorus- and nitrogen-containing oligomer : Preparation and thermal properties

A phosphorus- and nitrogen-containing compound (2-dimethylamino ethyl phenyl hydroxyethyl acrylate phosphate) and its oligomer (poly(2-dimethylamino ethyl phenyl hydroxyethyl acrylate phosphate), PDPHP) were synthesized and characterized. The polystyrene (PS) composites with various amounts of PDPHP were prepared by melt blending. The thermal stability of the PDPHP and PS composites was investigated by thermogravimetric analysis. The flame retardancy of the composites was evaluated using microscale combustion calorimeter and limiting oxygen index test. A Fourier transform infrared (FTIR) spectroscopy coupled with a thermogravimetric analyzer was also used to study the gas phase from the degradation of PS composites. The char residues of the PS composites containing 30 wt % PDPHP were analyzed by FTIR and scanning electron microscopy. The results suggest that the incorporation of PDPHP into PS can evidently enhance the char formation and improve the flame retardancy of virgin PS. The compact and coherent char formed during degradation was attributed to the enhancement of char quality and flame retardance. © 2011 Wiley Periodicals, Inc.