Evaluation of intumescent fire retardants and synergistic agents for use in wood flour/recycled polypropylene composites

Abstract The effects of fire retardant synergistic agents zinc borate (ZB), montmorillonite (MMT), manganese dioxide (MnO 2 ) and stannic oxide (SnO 2 ) on the mechanical properties, thermal degradation and flame retardant performance of wood flour–recycled polypropylene composites (WPC) comprised of intumescent flame retardants (IFR) were studied. The species were characterized by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 tests, and cone calorimeter measurements. The results showed that the synergistic effect between IFR and ZB or MnO 2 was greater than that of MMT or SnO 2 . The addition of 5 wt% of ZB or MnO 2 , MMT and SnO 2 created fire retardant WPC with a V0 rating, exhibiting excellent fire retardancy.