以聚乙烯醇(PVA)和石墨为原料,先以水为介质通过超声剥离膨胀石墨制备了纳米石墨微片(GNP)悬浮液,再直接加入到PVA中经溶液共混后流延成膜,制备了PVA/GNP复合膜;借助扫描电子显微镜、电阻测量仪和万能材料试验机等对复合膜进行了表征,研究了GNP含量及其在PVA基体中的分散状态对复合膜结构与性能的影响.结果表明,石墨片层被剥离成具有较大径厚比的GNP分散在PVA基体中;随着GNP含量的增加,复合膜的体积电阻率明显降低,力学性能先增大后降低,同时其耐水性和热稳定性均有所改善;GNP的含量为2％(质量分数,下同)时,复合膜的体积电阻率达到渗流阈值并下降到108数量级,拉伸强度提高了7.34 MPa,水接触角从56.3°提高至97.9(°).%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.
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