Preparation of Electrically Conductive Polyethersulfone/Expanded Graphite Nanocomposites and Its Property Study

Polyethersulfone(PES)/expanded graphite(EG) nanocomposites are prepared by a conventional melt compounding technique in order to improve the mechanical,thermal and electrical properties.The structure,thermal properties,electrical conductivity,mechanical properties and density of the PES/EG nanocomposites are investigated using transmission electron microscopy(TEM),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),x-ray diffractometer(XRD) and tensile analysis,respectively.The experimental results show that the PES/EG nanocomposite with 6% mass fraction of EG exhibits the best mechanical properties.TGA results indicate that the thermal stability(T-5%) of PES matrix increases about 4.8 ℃ because of EG incorporation.XRD patterns show that PES chains are intercalated into the layers of EG during melt compounding.TEM and SEM images show that EG nanosheets are uniformly dispersed in PES matrix with the thickness of about 10-30 nm,and the surface pre-treatment of EG benefits the dispersion.The electrical property testing indicates that the electrical conductivity of PES is improved significantly when 2% mass fraction of EG is added.Conductivity of composite material increases 12 orders of magnitude.That is,the PES/EG nanocomposite has a low percolation thresholds value of 2%.Considering mechanical and electrical properties,the mass fraction of EG addition should be less than 6%.