Poly(ethylene terephthalate)/expanded graphite conductive composites were prepared by the melt-blending method. The relationships between the preparation methods, microstructures, and conductivity properties of the composites were studied with scanning electron microscopy and conductivity measurements. The results showed that the composites presented a low percolation threshold and strong anisotropic conductivity. The epoxy resin had a strong intercalation effect on the expanded graphite that led to the easy formation of the conductive network. With classical statistical percolation theory, the conductivity behaviors of the cornposites were investigated. The results indicated that the nonuniversal critical exponent should be attributed to the a isotropy of conductivity, the tunneling conduction, and the particular structure. In addition, preliminary studies on the crystallization and dynamic mechanical behavior of the composites were performed. (c) 2008 Wiley Periodicals, Inc.