Abstract: Flame retardant rigid polyurethane foam （PUF） was prepared by a one?step method using black phosphorus/expanded graphite compound as a complex flame retardant， polyether polyol and isocyanate as raw materials， dibutyltin dilaurate as a catalyst， deionized water as a foaming agent. The physical， mechanical， and thermal properties of the resultant PUF samples were investigated through analyzing their apparent density， compression strength， and thermogravimetric behavior， and their flame?retardant performance was evaluated by limiting oxygen index （LOI）. The results indicated that the addition of a small amount of black phosphorus could improve the LOI value of PUF significantly. When the content of black phosphorus was 1 wt%， the sample “PUF?BP5” obtained an LOI 20.4 vol%， which was 30 % higher than that of pure PUF. The LOI of the sample “PUF?EG?BP5” reached 24.7 vol% at a graphite content of 7 wt% and a black?phosphorus content of 1 wt%. Such a result is higher than that of pure PUF by 60 %.

Key words: black phosphorus, expanded graphite, polyurethane foam, flame retardant, mechanical property, thermal performance