Solidification of non-halogen fire-retardant liquids by encapsulation within porous uniform PDVB microspheres for preparation of fire-retardant polymeric blends

Polystyrene/polydivinyl benzene (PS/PDVB) composite microspheres of narrow size distribution were prepared by a single-step swelling process of uniform PS microspheres with DVB and benzoyl peroxide, followed by polymerization of DVB within the microspheres. Dissolution of the PS template resulted in porous uniformly sized PDVB microspheres. New, solid, non-halogenated, fire-retardant composite microspheres of narrow size distribution were prepared by encapsulation of resorcinol bis (diphenyl phosphate) (RDP) within the pores of the PDVB microspheres. The encapsulation was performed by two different methods as follows: (1) vacuum and (2) heat/cool cycles. The loading capacity of the RDP into the PDVB particles was elucidated. PS/PDVB-RDP blends were prepared by mixing PS with the PDVB-RDP microspheres. Thermogravimetric analysis (TGA) illustrated that the thermal stability of the PS increases as the content (10–40 %) of the PDVB-RDP increased. Polycarbonate/poly(acrylonitrile-butadiene-styrene)/PDVB-RDP (PC/ABS/PDVB-RDP) blends were prepared by melting PC/ABS together with the PDVB-RDP microspheres at 250 °C and then pelleting it in an injection molding machine at 250 °C and 40 t. The improved thermal stability of the PC/ABS by blending it with PDVB-RDP was demonstrated by a vertical burn test on PC/ABS/PDVB-RDP bones.