In the present work, exfoliated graphite nanoplatelets (EGN) of 1 μm in average particle size,
which were prepared by heating at 900°C and then subjected to ultrasonic, ball-milling, and
vibratory ball-milling techniques, were uniformly incorporated into phenylethynyl-terminated
polyimide (PETI-5) resin. The fracture surface morphology and the electrical resistivity of the
EGN/PETI-5 composites were investigated. The results showed that the fracture surfaces and
the electrical resistivity strongly depended on the EGN content. The fracture surfaces became
more ductile and roughened with increasing EGN and the electrical resistivity was gradually
decreased with increased EGN loading, indicating the percolation threshold at 5 wt% EGN.