Abstract: Expanded graphite/poly (ethylene terephthalate) ( EG/PET) conductive composites were prepared by
the melt2blending method. The effect s of the preparation method on the microst ructures and conductivity properties of the composites were studied by scanning elect ron microscopy (SEM) and conductivity measurement. The results show that the graphite nanosheet s are effectively dispersed in the PET matrix with the assistance of the shear effect on EG and the interaction between EG and PET, which promotes the formation of the conductive network and makes the percolation threshold value of EG/ PET composites only 3. 14 %. The strong mutual effects between the epoxy group and the functional groups on EG surface cause the epoxy resin to exert more exfoliation effect on EG,which leads to the percolation value to descend to 1. 80 %. Using the classic statistic percolation theory, the conductivity behavior of the composites was investigated. The nonuniversal critical exponent ( t) should be at tributed to the anisotropy of conductivity, the existence of the tunneling conduction above the percolation threshold and the particular structure.