Abstract: Effect of trichloroethyl phosphate (TCEP) on the microstructure, flame retardancy, expansion ratio, and compression strength of polyurethane sealing materials was studied. Maximum limited oxygen index of polyurethane sealing materials increased from 20.0 % to 23.4 % when the TCEP content increased from 0 to 20 %, The expansion ratio of polyurethane sealing materials decreased at first and then increased with the content of TCEP increasing. Main structure of polyurethane sealing materials with flame retardant is not changed，but flame retardant has effect on the properties and morphology of the foam.

Key words: polyurethane, gas sealing material, gas barrier performance, expansion ratio, trichloroethyl phosphate