Abstract: A novel halogen-free nitrogen-contained phosphaphenanthrene flame retardant DOPMI was synthesized from 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO) and N-phenyl maleimide (N-PMI). DOPMI was characterized by FT-IR, LC/MS, TG and DSC. The effect of DOPMI and other flame retardants on the flame-retardancy, mechanical properties, thermal degradation behavior, and charmorphology of PC was investigated after blending these retardants with PC. Results showed that LOI was raised to 30.4% and V-0 rating was observed from UL 94 when 3% DOPMI, 2% methyl phenyl silicone (MPS) and 24% phosphorus-containing flame-retardant PET were blended with PC. Notched impact strength and tensile strength decreased after the flame retardants were added. DOPMI couldn’t improve the char yield of PC, but it could accelerate crosslinking and char forming of PC. Additionally, SEM photos indicated that DOPMI could promote PC foaming, and MPS had the synergistic effect on PC.

Key words: halogen-free, nitrogen-contained phosphaphenanthrene, flame retardant, polycarbonate, synergistic effect