氧化石墨烯增强聚乙烯醇机械性能的机理研究

Study of enhanced mechanical performance in polyvinyl alcohol/graphene oxide nanocomposites

通过控制聚乙烯醇/氧化石墨烯(polyvinyl alcohol/graphene oxide,PVA/GO)复合材料在恒温、恒湿环境中放置的时间,发现氧化石墨烯对聚乙烯醇基体机械强度的提高是1种表观增强现象。干燥状态下氧化石墨烯对聚乙烯醇基体没有明显的机械性能增强作用,当基体在恒温恒湿的环境中放置3~5d后,复合材料的机械能高于纯样。由于氧化石墨烯的存在阻碍了水分子进入基体内部,保持了基体分子在干燥状态下已经形成的分子间氢键(PVA-PVA),使聚乙烯醇基体能长时间在一定湿度环境中保持高的机械强度。通过对比研究发现,大面积片层氧化石墨烯(100~300μm2)比小面积片层氧化石墨烯(1~3μm2)有更高的水阻隔性,因此大面积片层氧化石墨烯更利于维持聚乙烯醇基体高的机械强度。

The mechanism of enhanced mechanical performance in polyvinyl alcohol/graphene oxide（PVA/GO）nanocomposites was studied by holding them in the constant temperature and humidity condition.The enhanced mechanical performance of the nanocomposites was an apparent phenomenon.In the dry condition,the graphene oxide sheets cannot improve the mechanical properties of PVA/GO nanocomposites.On the other hand,the mechanical properties of nanocomposites is higher than that of pure PVA after keeping them in the constant temperature and humidity condition for 3-5d.The graphene sheets can prevent water molecules into the PVA chains,and kept the existed intermolecular hydrogen bond between the PVA molecular chains（PVAPVA）.Therefore,the high mechanical properties of PVA/GO nanocomposites could be maintained for a long time in the humid environment.Comparative study shows that the large area GO sheets（100-300μm^2）exhibit better water resistance property than that of the small ones（1-3μm^2）,resulting in higher mechanical properties for PVA matrix.