Abstract: In this study, layered material lanthanum phenylphosphonate (LaPP) was synthesized by reflux method and the surface of LaPP was grafted modified by hexachlorocyclotriphosphonitrile (HCCP) in order to improve the thermal stability and flame retardancy of epoxy resin (EP). As a result, HCCP-LaPP was created and used to the preparation of HCCP-LaPP/EP composites. In addition, the synergistic effect of LaPP and HCCP on the flame-retardancy and thermal stability of EP was studied. The results show that the addition of HCCP-LaPP can significantly improve the thermal stability and residues weight of EP composites at higher temperatures. Conical calorimeter test results show that compared with those of pure EP, the THR and TSP of 6% mass HCCP-LaPP/EP reduced by 39.9% and 24.6%, respectively. Meanwhile, the LOI value was increased from 25.7% to 30.3%, the UL-94 rating was enhanced from NR to V-1 and the residues weight of 6% HCCP-LaPP/EP composites was 25.7% while the pure EP had only 18.5% at 700 ℃. It is proved that HCCP-LaPP has a good synergistic effect in flame retardant EP. Excellent carbonization, lamellar barrier and phosphorus and nitrogen coeffect of LaPP and HCCP make the flame retardancy, smoke suppression and thermal stability of EP composites significantly improved.

Key words: epoxyresins, lanthanum phenylphosphonate, hexachlorocyclotriphosphonitril, flame retardant