Cross-linking of a novel reactive polymeric intumescent flame retardant to ABS copolymer and its flame retardancy properties

In this work, a reactive polymeric intumescent flame retardant (PDSPB) was synthesized and applied to ABS resin. The flame retarded materials were prepared by direct melt blending of ABS and PDSPB (ABS/PDSPB), as well as melt cross-linking of PDSPB to ABS (ABS-c-PDSPB). The cross-linking reaction was characterized by fourier transform infrared spectrometry (FTIR) and gel content measurement. The thermal stability, flame retardancy, carbonization chemistry and dynamic mechanical properties were investigated by TGA, dynamic FTIR, SEM, CONE calorimetry and dynamic mechanical analysis (DMA). The results showed that the addition of PDSPB can effectively reduce the flammability properties including peak heat release rate (PHRR), total heat release (THR) and average mass loss rate (AMLR). An improvement of the limited oxygen index value was also observed. Especially, the cross-linking of PDSPB can improve the ignition time and reduce THR during combustion. Moreover, ABS-c-PDSPB displayed a more obvious intumescent char layer and char weight than that of ABS/PDSPB blends. Furthermore, cross-linking of PDSPB enhanced the thermal stability and considerably delayed the thermal oxidation degradation of ABS. The dynamic mechanical properties were improved and the plasticization effect was reduced by cross-linking of PDSPB.