SYNTHESIS OF A HYPERBRANCHED POLYMER WITH DIFFERENT OXIDATION STATES OF PHOSPHORUS AS AN EFFICIENT FLAME RETARDANT FOR EPOXY RESIN

摘要

A hyperbranched poly(phosphonamidate-phosphonate) (HPPAPO) was synthesized by the condensation of phenylphosphonic dichloride (PPDC) and Trihydroxymethylphosphine oxide (THPO) and end-capping with aniline.HPPAPO was used as an additive-type flame retardant for diglycidyl ether of bisphenol A (DGEBA) epoxy resin (EP) cured by 4,4'-diamino-diphenyl methane (DDM) and it exhibited excellent flame retardant effects.With only 5 wt.％ HPPAPO incorporated, the flame retardant thermoset received UL-94 V-0 rating with the LOI value of 35.5％.The digital images of the epoxy thermosets after LOI tests indicate that HPPAPO promotes the flame retardant thermosets to form thicker and more char layers compared to the neat sample.Furthermore, the data of Thermal gravimetric analysis (TGA) disclose more char yields both under nitrogen and air and the enhancement of thermo-oxidative stabilities at higher temperatures for flame retardant epoxy resins.The condensed phase effects endow the epoxy resin composites better flame retardancy.