Poly(ethylene terephthalate)/exfoliated graphite nanocomposites with improved thermal stability, mechanical and electrical properties

A series of nanocomposites based on poly(ethylene terephthalate) (PET) and exfoliated graphite (EG) are prepared by melt-compounding method and their morphology, structures, thermal stability, mechanical and electrical properties are then investigated. For manufacturing the nanocomposites, EG, which is composed of disordered graphene sheets, is prepared by the acid-treatment and following rapid thermal expansion of micron-sized crystalline natural graphites. It is characterized that disordered graphene sheets of EG are well dispersed in the PET matrix without forming crystalline aggregates even at high EG content of 7.0 wt.%. Accordingly, thermal and thermo-oxidative degradation temperatures of PET/EG nanocomposites are improved substantially with the increment of EG content. In addition, dynamic storage moduli of the nanocomposites increase noticeably with increasing the EG content. The electrical conduction path of graphene sheets in the nanocomposites is formed at ∼5 wt.% EG.