The conductive property of polyurethane/expanded graphite powder composite foams

Polyurethane (PU)/expanded graphite powder (EGp) composite foams have been prepared by filling mold curing reaction. The morphology and electrical properties of the prepared PU/EGp composite foams have been investigated. The percolation threshold effect of PU/EGp composite foams occur at the content around 5 wt% of the EGp, which is much lower than that of graphite nanosheets (GN) composite and carbon black (CB) composite. The resistivity of PU/EGp and PU/GN composite foams can reach at about 10(6) Omega.cm, while CB system can only reach at about 10(8) Omega.cm. The resistance of PU/EGp composite foams shows negative temperature coefficient effect and negative pressure coefficient effect.