The effect of mechanical stress on electric resistance of nanographite-epoxy composites

The in-plane electric resistance Ra of composite materials (CMs) thermoexfoliated graphite(TEG)-epoxy resin(ED) under compression along compacting C-axis has been investigated by four-probe method. TEG content was 5–75 wt%. It was shown that specimens prepared by cold pressing are denser and reveal lower values of electric resistivity in comparison with specimens prepared by pouring. It was found that compression of the specimens leads to plastic deformation of specimens (εpl) and essential irreversible decrease of electric resistance during the first cycle of loading (up to 50 MPa), especially for the poured specimens with low density. Within the proposed model the contact resistance Rk between graphite particles in CM has been evaluated and it was shown that it increased with the decrease in TEG content in CM and depends on compacting method of CMs and the dispersity of graphite filler.

► Graphite-epoxy composites (CMs) under compression have been studied.
► DC resistance of CMs decreases under compression.
► Number of fillers' chains and resistance Rk between fillers determine CM resistivity.
► Fillers' morphology and fabrication method of CMs influence Rk value.