Effects of interfacial modification on the thermal, mechanical, and fire properties of high‐impact polystyrene/microencapsulated red phosphorous

In this study, polystyrene (PS)‐encapsulated magnesium hydroxide‐microencapsulated red phosphorus (MHRP) was prepared by in situ polymerization of styrene on the surface of MHRP in a high speed mixer. The encapsulated MHRP flame retardant was successfully applied in the fire resistance to HIPS by melt blending in a corotating twin‐screw extruder. The effects of PS‐encapsulated MHRP on the properties of HIPS composites were studied by mechanical, thermal, and combustion tests (HBR, LOI, UL‐94, and cone calorimetry). The experimental results showed that compared to the composites containing untreated MHRP, the thermal, mechanical, and flame‐ retardant properties of those containing PS‐encapsulated MHRP were found to be prominently improved. This improvement was mostly attributed to an effective dispersion of the encapsulated filler and a good interfacial compatibility between the filler and the matrix.