Achieving ultrahigh glass transition temperature, halogen-free and phosphorus-free intrinsic flame retardancy for bismaleimide resin through building network with diallyloxydiphenyldisulfide

A novel type of intrinsic flame retardant thermosetting resin without halogen and phosphorus elements (BDS) was developed based on building crosslinked network with a new disulfide-containing aryl allyl ether compound (DS) and bismaleimide. The molar ratio of DS to bismaleimide has a significant effect on performances of BDS resins, the resin (BDS-0.86) of which the molar ratio of DS to bismaleimide is 0.86 shows the best integrated performances including outstanding flame retardancy, high flexural strength (128.2 ± 8.6 MPa) and the highest glass transition temperature (336 °C) among halogen-free and phosphorus-free flame retarding bismaleimide resins reported so far. The origin of superior integrated performances of BDS-0.86 was intensively discussed from molecular structures and curing mechanism.