The thermal degradation behavior and combustion of rigid polyurethane foams (RPUF) with expandable graphite (EG) and ammonium polyphosphate (APP) were investigated by thermal gravimetric analysis (TG)

X-ray photoelectron spectroscopy (XPS)

limiting oxygen index (LOI) and smoke density test.On this basis

the effect of EG/APP on the combustion of RPUF/tris(-chloroisopropyl)phosphate (TCPP) composites was studied by CONE calorimeter.The results showed that the interaction between EG and APP led to lower weight loss rate of EG/APP at high temperatures and a significant increase of char residue at 800℃.The char formation between EG/APP and RPUF could be mainly contributed by APP.Compared with RPUF

the LOI of RPUF/EG/APP increased from 19.8% to 35.4% and the smoke density changed little.Compared with the RPUF/EG

RPUF/APP and RPUF/EG/APP

the more the amount and the higher thermal oxidation resistance of char residue

the higher the LOI is;the more compact of the residue surface

the lower the smoke released is.It was found that the heat release

smoke production rate and CO release rate of RPUF/TCPP were decreased significantly by the addition of EG/APP.The results embodied the advantages of a combination of chemical and physical intumescent flame retardants in the EG/APP system.