Study Of A Novel Phosphorus-containing Flame Retardant Epoxy Resin

A reactive phosphorus-containing compound, bis-phenoxy (3-hydroxy) phenyl phosphine oxide (BPHPPO) was first successfully synthesized by using resorcinol and phenyl phosphonic dichloride (PPD). The chemical structure of BPHPPO was characterized with FTIR, MS and ¹H NMR. The synthesized BPHPPO was used to produce the phosphorus-containing epoxy resin (BPHPPO-EP), and the sodium hydroxide was added to catalyze the reaction. The chemical structure of BPHPPO-EP was also characterized with FTIR and ¹H NMR. The epoxy equivalent weight of BPHPPO-EP was 0.442, which was tested by the modified hydrochloric acid and acetone method. Thermal degradation behaviors and the thermo-stability of the cured epoxy resins were investigated with the thermogravimetric analysis (TGA). 4-4'-diaminodiphenysulfone (DDS) was used as a curing agent. It could be noted that the cured BPHPPO-EP has exhibited higher char yield (51.8% in the N₂ at 800℃), this result indicated that the thermo-stability of BPHPPO-EP/DDS is much better than that of TBBA-EP/DDS and BA-EP/DDS. The flame retardant property of cured epoxy resins was measured by the LOI test. The LOI of the cured BPHPPO-EP/DDS is 34. It is clear that the flame retardancy of the cured BPHPPO-EP is much better than that of cured BA-EP and TBBA-EP. Even more, the fume of the cured BPHPPO-EP/DDS generated in the combustion is much fewer than that of the cured BA-EP and TBBA-EP. This research can provide a basis for developing phosphorus-containing epoxy resins with excellent combination property by usingBPHPPO.