多层石墨烯增强聚合物基复合材料的力学性能研究

发布时间：2018-08-11 18:23

【摘要】：石墨烯具有独特的石墨片层结构、优异的理化性能,作为高性能纳米填料在聚合物复合材料领域具有极其广阔的应用前景。目前石墨烯/聚合物复合材料的研究尚处于起步阶段,并且存在石墨烯质量不稳定、增强效果不显著、缺乏显示度高的代表性研究工作,以及现有制备工艺无法满足规模化工业生产等一系列问题,极大限制了石墨烯在复合材料领域的规模化工业应用。本论文立足于低成本宏量制备石墨烯技术的最新进展,采用插层膨胀法制备的多层石墨烯作为增强材料,选取代表性的聚氯乙烯树脂和环氧树脂作为聚合物基体,结合传统的熔融共混和树脂传递成型工艺,通过结构设计和工艺优化,制备具有显著力学增强效果的石墨烯/聚合物复合材料。本论文包括以下两方面的内容:针对聚氯乙烯抗冲击性能差的关键问题,我们提出利用多层石墨烯所高比表面积、蜷曲形态和高柔性的特点,显著改善硬质聚氯乙烯复合材料的抗冲击韧性。研究表明,添加少量石墨烯(0.36 wt%)可以显著提高复合材料的断裂韧性和缺口冲击强度,归因于石墨烯的高度柔性和蜷曲形态,其在复合材料内部起到近似于“弹性体”的增韧作用;此外石墨烯的加入还使得与之相邻的聚氯乙烯分子链具有更大的运动空间,进而使得石墨烯/聚氯乙烯复合材料的韧性显著提高。为了实现石墨烯在树脂基体中的均匀分散,我们提出原位聚合制备石墨烯/聚氯乙烯复合树脂粒料的方法,结合传统的熔融共混工艺制备石墨烯/聚氯乙烯复合材料。研究表明,添加极少量的多层石墨烯(0.3 wt%)可以显著提高复合材料的力学强度和韧性。这种显著的力学增强主要归因于多层石墨烯独特的柔软片层结构、高度结构完整性、石墨烯在基体中的均匀分散,以及石墨烯与基体之间的较强相互作用。为了改善石墨烯在聚合物基体内的分散、获得显著的复合材料力学增强效果,我们选用三维石墨烯/泡沫镍网络作为增强体、通过传统树脂传递工艺制备石墨烯/环氧树脂复合材料,考察石墨烯对于泡沫镍以及复合材料的力学增强作用。研究表明石墨烯对泡沫镍的表面包覆可以显著提升石墨烯/泡沫镍混杂材料的压缩模量、弯曲模量以及阻尼因子(分别提高20%、132%和184%),主要归因于石墨烯与基体的较强界面结合、混杂材料的环箍效应、以及混杂材料的丰富界面。此外,石墨烯/泡沫镍/环氧树脂复合材料相比于环氧树脂具有更高的储能模量和损耗模量,相比于泡沫镍/环氧树脂复合材料具有更加优异的粘弹阻尼性能(阻尼因子提高184%)。这主要归因于石墨烯/泡沫镍/环氧树脂复合材料的丰富界面、石墨烯与环氧树脂之间的界面滑移。综上所述,通过设计并调控石墨烯在聚合物基体中的结构和形态,可以实现对石墨烯/聚合物复合材料力学性能的有效调控;结合结构设计和工艺优化可以获得高性能的石墨烯/聚合物复合材料,有助于推动石墨烯在复合材料工业中的规模化应用,并在航空航天、交通运输、建筑机械等诸多领域具有广阔的应用前景。
[Abstract]:Graphene has unique graphite lamellar structure and excellent physicochemical properties. As a high-performance nano-filler, graphene has a very broad application prospect in the field of polymer composites. A series of problems, such as the high representative research work and the inability of the existing preparation process to meet the needs of large-scale industrial production, limit the large-scale industrial application of graphene in the field of composite materials. Graphene/polymer composites with remarkable mechanical reinforcing effect were prepared by means of structural design and process optimization with typical PVC resin and epoxy resin as polymer matrix and traditional melt blending and resin transfer molding process. The key problem of the poor impact resistance of polyvinyl chloride (PVC) is that the high specific surface area, curl shape and high flexibility of multilayer graphene are used to improve the impact toughness of rigid PVC composites. Due to the high flexibility and curling morphology of graphene, graphene plays a toughening role similar to "elastomer" in the interior of the composites. In addition, the addition of graphene makes the adjacent PVC molecular chains have more space for movement, thus making the toughness of graphene/PVC composites significantly improved. Graphene/PVC composites were prepared by in-situ polymerization and conventional melt blending process. The results show that the mechanical strength and toughness of the composites can be improved significantly by adding a small amount of graphene (0.3 wt%). This remarkable mechanical enhancement is attributed to the unique soft lamellar structure, high structural integrity, uniform dispersion of graphene in the matrix, and strong interaction between graphene and matrix. In order to improve the dispersion of graphene in the polymer matrix, remarkable mechanical reinforcement effect of the composites is obtained. Graphene/epoxy resin composites were prepared by traditional resin transfer process using three-dimensional graphene/nickel foam network as reinforcement. The mechanical reinforcing effect of graphene on foamed nickel and its composites was investigated. The results show that graphene coating on foamed nickel can significantly improve graphene/nickel foam hybrid materials. Compressive modulus, flexural modulus and damping factor (increased by 20%, 132% and 184% respectively) are mainly attributed to the strong interface bonding between graphene and matrix, ring hoop effect of hybrid materials, and rich interface of hybrid materials. Compared with nickel foam/epoxy resin composites, graphene/nickel foam/epoxy resin composites have better viscoelastic damping properties (damping factor increased by 184%). This is mainly due to the rich interface between graphene/nickel foam/epoxy resin composites and the interface slip between graphene and epoxy resin. The structure and morphology of graphene/polymer composites can effectively control the mechanical properties of graphene/polymer composites; high performance graphene/polymer composites can be obtained by combining structural design and process optimization, which is helpful to promote the large-scale application of graphene in composite industry and in aerospace, transportation, construction machinery. Many other fields have broad application prospects.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332;TQ327

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