Cover Image, Volume 131, Issue 11



Rigid polyurethane foam (RPUF) is widely used for industrial purposes, but its applications are limited because it is very flammable and releases toxic gases while burning. Traditional flame retardants for RPUF release toxic and corrosive gases, while other flame retardants are water-soluble, which can reduce the flame retardancy. To overcome water solubility and the deterioration of the foam's mechanical properties when flame-retardant additives are incorporated, Deng-Hui Wu et al. synthesize a novel phosphoruse-nitrogen containing the single intumescent flame retardant, toluidine spirocyclic pentaerythritol bisphosphonate (TSPB). The results show that TSPB exhibits better compatibility with RPUF, and that TSPB-RPUF possesses outstanding water resistance. The cover shows an SEM image of RPUF. DOI: 10.1002/app.39581