Abstract: In this work, graphite nanoplatelets (GNP) were prepared by the ultrasonic exfoliation of expanded graphite in distilled water, and then poly(vinyl alcohol) (PVA)/GNP composite films were prepared by a solution casting method using the mixture of PVA and GNP. The effects of GNP content and its dispersion in PVA matrix on the structure and properties of the composite films were investigated by means of scanning electron microscopy, resistivity tester and universal material tester. The results indicated that the graphite had been well exfoliated into GNP with a high diameter-to-thickness ratio and also well dispersed in the matrix. The volume resistivity and water resistance of the composite films decreased continuously with an increase of GNP content, whereas their mechanical properties exhibited an increase at first and then tended to decrease. Most of all, the composite films containing 2 wt % GNP achieved the optimum performance. Its volume resistivity was reduced to 108 Ω·cm as an electrical percolation threshold and its tensile strength was improved to 7.34 MPa. Meanwhile, its water contact angle increased from 56.3 ° to 97.9 °, indicating better water resistance and hydrophilic properties in comparison with pure PVA.

Key words: poly（vinyl alcohol）, graphite nanoplatelet, volume resistivity, mechanical property, water resistance