عنوان مقاله [English]
Electrically conductive coatings are mainly required for static charge dissipation and electromagnetic/radio frequency interference (EMI/RFI) shielding. Electrically conductive coatings are prepared by the incorporation of the metallic pigments/graphite or carbon black onto the binder. In the present investigation, a study on the correlation between electrical, percolation threshold, filler volume concentration and some other physical and mechanical properties for graphite filled epoxy coating was carried out through an examination of the filler concentration dependence of the volume resistivity and other mechanical properties. The impact strength of epoxy resin filled with graphite was also investigated. A decrease in impact strength with an increase in filler content was observed. It is found that there are two critical threshold, in plot of electrical resistivity v.s. filler volume concentration. The adhesion of the filled resin to substrate was also determined by pull-off test. A decrease in the adhesion to substrate with an increase in filler content was observed in Then to find out the correlation between filler concentration and viscoelastic behavior of the system tensile test carried out. Then for expand a theory that can explain the transfer between insulator-semiconductor and semiconductor-conductor behavior of graphite filled system images was gived by SEM and optical microscopy and also oil absorption (for determine CPVC) test carried out. All data show that formation of internal network by graphite particles and particle by particle contact of them is the reason of formation a conductive network in epoxy system.