Wenmin Wei’s research while affiliated with Hubei University of Technology and other places

Highly conductive graphite/acrylonitrile–butadiene–styrene copolymer (ABS) composites were prepared via foaming with supercritical carbon dioxide (scCO2), followed by de-foaming with an open mixing mill. This processing technique decreased the direct current resistivity of the composites by about 1 order of magnitude. The alternating current (AC) resistivity results demonstrated that an insulator-semiconductor transition occurred upon increasing the graphite content. In analyzing the AC impedance, it was shown that the response characteristics changed from capacitive to resistive at significantly lower graphite loading levels for composites processed with scCO2. The dispersion of graphite in the copolymer matrix was characterized by scanning electron microscopy (SEM), rheometry and dynamic mechanical analysis. SEM of graphite/ABS composites revealed that the graphite was very well-dispersed. The sample treated with scCO2 processing showed higher storage modulus and complex viscosity than those processed conventionally. Additionally, the Tg was increased by 2–3 °C after the scCO2 processing treatment. This approach to composites processing with scCO2 represents an attractive method for preparing electrically conductive composites with well-dispersed fillers.