Abstract: In this paper, polyurethane foam (PUF) were prepared from glycerolysized castor oil and castor oil phosphate polyol, and MDI, expanded graphite was introduced as a flame retardant. The mechanical behavior and flame resistance of PUF was studied by universal testing, limiting oxygen index, thermogravimetric analysis, and scanning electron microscope. The expanded graphite improved the flame retardant, thermostability, and mechanical strength of polyurethane foam. The synergistic effect between expanded graphite and triethyl phosphate caused the formation of a dense char layer, which inhibited the transfer of heat and combustible gas, and the limiting oxygen index of PUF increased to 29.7 %.

Key words: polyurethane, castor oil, triethyl phosphate, expanded graphite, flame retardancy