Characterizations of expanded graphite/polymer composites prepared by in situ polymerization

• Published in: Carbon (New York) 2004, Vol.42 (14), p.2839-2847
• Main Authors: Zheng, Genhua, Wu, Jingshen, Wang, Wenping, Pan, Caiyuan
• Format: Article
• Language: English
• Subjects: A. Carbon composite, Graphite oxide, Resins; B. Intercalation; Cross-disciplinary physics: materials science; rheology; D. Electrical properties; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Materials science; Physics; Specific materials
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2004.06.029

Poly(styrene- co-acrylonitrile)/expanded graphite composite sheets with very low in-plane (8.5 × 10 −3 Ω cm) and through-thickness (1.2 × 10 −2 Ω cm) electrical resistivities have been prepared. The expanded graphite was made by oxidation of natural graphite flakes, followed by thermal expansion at 600 °C. Microscopic results disclosed that the expanded graphite has a legume-like structure, and each “legume” has a honeycomb sub-structure with many diamond-shaped pores. After soaking the expanded graphite with styrene and acrylonitrile monomers, the polymer/expanded graphite composite granules were obtained by in situ polymerization of the monomers inside the pores at 80 °C. The functional groups and microstructures of the oxidized graphite, expanded graphite and composites in the forms of particles or sheets were carefully characterized using various techniques, including X-ray powder diffraction, thermogravimetry, optical and electron microscopy. It was found that the honeycomb sub-structure survived after hot-pressing, resulting in a graphite network penetrating through the entire composite body, which produces a composite with excellent electrical conductivity.