【作者】 李亚军；

【导师】 戴礼兴；

【作者基本信息】 苏州大学 ， 材料科学与工程， 2016， 硕士

【摘要】 由于石墨烯的优异性能,将石墨烯与聚合物进行复合制备高聚物纳米复合材料已成为近年来的研究热点。本文将经过前处理的石墨烯与聚乙烯醇复合并制成纤维,对纤维的制备及其结构性能进行了研究。一方面,对氧化石墨烯(GO)进行还原处理,将还原的氧化石墨烯(r GO)作为纳米填料,与聚乙烯醇(PVA)复合并纺制成纤维,PVA纤维的力学性能得到明显改善;另一方面,通过前处理制备大尺寸、窄分布的高浓度GO悬浮液,并以GO为主体,通过添加少量PVA增加GO片层之间的相互作用,从而制备出具有一定柔韧性的GO纤维。本文主要研究内容和结论如下:(1)使用Hummers法制备GO,并通过原花青素对其进行还原,然后对还原效果、rGO表面吸附状态及其分散性进行了相关表征。结果表明,原花青素可以显著去除GO表面的含氧官能团,实现GO的高效还原;同时部分原花青素会吸附在rGO表面,从而起到分散剂的作用,使rGO能良好地分散在常见溶剂中。(2)通过湿法纺丝和后续的热拉伸制备了不同rGO含量的PVA/rGO复合纤维,并对复合纤维的表面形貌、结晶性能、力学性能进行了相关研究。结果表明,rGO与PVA基体之间存在较强的界面作用,随着rGO含量的逐渐增大,复合纤维的动态力学性能和拉伸性能呈现先增大后减小的趋势,当rGO含量为2.0 wt%时,能获得最佳的增强效果。(3)通过改进的氧化和分离方法,制备了大尺寸、窄分布的高浓度GO悬浮液,向其中加入PVA使GO片“粘结”在一起,首次通过加入硼酸使体系发生交联以提高悬浮液的粘度,进而改善GO的成纤性。GO悬浮液的粘度和形态测试结果表明,PVA和硼酸的加入不仅可以提高GO悬浮液的粘度,还能够使其保持液晶形态。(4)以氢氧化钠的甲醇溶液作为凝固浴,利用湿法纺丝技术将添加PVA并经硼酸改性的GO悬浮液纺制成纤维,进一步将所得纤维浸在甲醇中充分收缩,并以氢碘酸进行还原,得到rGO纤维。对纺丝原液及纤维进行相关的测试表征,结果表明:PVA和硼酸的协同作用显著改善了GO悬浮液的可纺性,增大了石墨烯片层间的相互作用,使纤维变得密实,并且在甲醇中收缩后,可以获得形态较为规则的纤维,而且纤维的力学性能获得明显提升。更多还原

【Abstract】 Due to the excellent properties of graphene, the preparation of polymer nanocomposites have become a hot research topic in recent year. The composite fiber of poly（vinyl alcohol） and graphene with pretreatment was prepared and the structure and properties of the composite fiber were studied. On the one hand, by putting reduced graphene oxide（rGO） with high strength and high modulus into poly（vinyl alcohol）（PVA） matrix, PVA/rGO composite fibers with enhanced mechanical properties can be prepared. On the other hand, large graphene oxide suspension with narrow distribution and high concentration was prepared through pretreatment. And then by using a small amount of PVA as the ‘binder’ of graphene nanosheets, the interaction between graphene sheets can be significantly strengthened. On this basis, the prepared graphene fiber can possess obviously improved mechanical properties and at the same time maintain the flexibility of PVA.The main research details and conclusions are as follows:（1） The graphene oxide（GO） was prepared by Hummers’ method, and was reduced by oligomeric proanthocyanidin（OPC）. The reduction effect, the surface adsorption state and the dispersibility of rGO were characterized. The results show that most of oxygencontaining groups of GO can be removed by OPC. At the same time, some OPC molecules that combined with rGO sheets can serve as the dispersant of rGO and improve the dispersibility of rGO in solvents.（2） Continuous PVA/rGO composite fibers with different rGO loadings were prepared by wet spinning followed by hot drawing, and the surface morphology, crystalline properties and mechanical properties of the composite fibers were studied. The results show that there is a strong interfacial interaction between rGO and PVA matrix. In addition, the dynamic mechanical properties and tensile properties of the composite fibers exhibit a trend of first increasing and then decreasing with the increasing of rGO loading. And when rGO loading reaches 2.0 wt%, the optimum reinforcement is achieved.（3） Through improved oxidation and separation methods, we successfully prepared large graphene oxide（LGO） suspension with narrow distribution and high concentrations. The viscosity of graphene suspension and the morphology under polarized optical microscopy（POM） were characterized after PVA was added into the suspension and cross-linked with boric acid. The results show that the addition of PVA and boric acid could greatly increases the viscosity of the suspension, and the final suspension shows liquid crystal morphology.（4） With NaOH/CH₃ OH solution as the coagulation both, the LGO suspension with PVA and boric acid was wet-spun to prepare graphene fiber followed by shrunk in methanol and reduced by hydrogen iodate. The morphology and the mechanical property of the graphene fiber was characterized. The results show that the interaction between graphene sheets and the spinnability of the suspension can be increased by adding of PVA and boric acid. The shrinking treatment in methanol can make the graphene fiber become tight and obtain a relatively regular cross section. What’s more, the graphene fiber has a significantly improved mechanical property.更多还原