Influences of exfoliated graphite on structures, thermal stability, mechanical modulus, and electrical resistivity of poly(butylene terephthalate)

We report structural features and multifunctional properties of nanocomposites based on poly(butylene terephthalate) (PBT) and exfoliated graphite (EG), which are manufactured by melt-compounding technique. Scanning electron microscope and X-ray diffraction data exhibit that graphene platelets of EG are well dispersed and exfoliated in the PBT matrix even at high EG content of 7.0 wt %. Raman spectra support that graphene platelets of EG are interacted specifically with phenyl rings of PBT chains at nanocomposite interfaces. DSC cooling and following heating thermograms of the nanocomposites demonstrate that graphene platelets of EG play a role as effective nucleating agents for PBT a-phase crystals and thus lead to accelerating the overall crystallization of the nanocomposites. Thermal stability of PBT/EG nanocomposites is improved substantially due to the gas barrier effect of graphene platelets of EG dispersed in the PBT matrix, especially at the active oxygen gas condition. Dynamic mechanical modulus of the nanocomposites is also enhanced significantly with increasing the EG content. The electrical volume resistivity of the nanocomposites is decreased dramatically from similar to 1018 to similar to 106 O cm by forming the electrical conduction path at a certain EG content between 3 and 5 wt %. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012