【作者】 赵永华；

【导师】 马兆昆；

【作者基本信息】 北京化工大学 ， 材料科学与工程， 2015， 硕士

【摘要】 碳纤维(CF)是含碳量在90%以上的无机纤维,与树脂基体经复合工艺制得的复合材料性能优异,已广泛应用在航空航天、导弹和民用领域。碳纤维复合材料的力学性能与碳纤维和基体的界面粘接性能相关,未经处理的碳纤维的表面能低,表面微晶尺寸较大,与树脂基体的界面结合较弱,因此要对碳纤维进行表面处理。本文的研究目的就是通过各种方法进行碳纤维的表面改性,以提高碳纤维复合材料的力学性能及层间性能。碳纳米管、石墨烯自问世以来,一直是碳材料研究的焦点,通过处理可以获得丰富的活性官能团及良好的分散性,用其处理碳纤维表面,可以显著改善碳纤维与基体树脂的界面性能。首先,本文通过对碳纤维表面碳纳米管的连续化生长工艺的探究来对碳纤维进行表面改性,方法是：碳纤维走丝经卧式碳化炉时,采用化学气相沉积法在碳纤维表面生长碳纳米管。本文经过详细讨论及大量实验研究可能影响碳纤维表面生长碳纳米管的连续化生产工艺的各种参数后,确定了最佳的连续化工艺：即利用低温燃烧法对碳纤维进行去胶处理,选择二茂铁作为催化剂,以二甲苯为溶剂；选择750℃,氮气吹扫,控制含碳气体与氮气的比例；碳纤维以8m/h走丝速度连续穿过石英管,实现碳纤维表面碳纳米管的连续化生长,通过扫描电镜(SEM)及透射电镜(TEM)等测试分析,可观察到碳纤维表面有一层直径为20-100nm、长度为2-5um的碳纳米管。通过化学接枝改性的方法对碳纤维进行表面处理,主要方法为碳纤维接枝碳纳米管、碳纤维接枝氧化石墨烯。1)碳纤维接枝碳纳米管的机理为：以乙二胺为中间体,采用水热法,将酸化的碳纳米管接枝到处理的碳纤维上；本文经过详细的实验及讨论确定了碳纤维接枝碳纳米管的最佳工艺为：以碳纳米管：N,N-二甲基甲酰胺为1(g)：1000(ml)的比例,在其中一定量的乙二胺；将碳纤维加入水热釜,将水热釜放入180℃烘箱中反应48h,得到多尺度增强体。2)碳纤维接枝氧化石墨烯：利用硅烷偶联剂KH550处理酸化处理的T300碳纤维,将碳纤维放入由改进H法制备的氧化石墨烯水溶液中,通过碳纤维表面的硅烷偶联剂与氧化石墨烯之间的电荷吸附作用及化学反应,然后通过热处理将氧化石墨烯接枝到碳纤维表面,并对碳纤维多尺度增强体表面官能团、表面形貌、表面结构进行了分析,由于石墨烯包覆碳纤维的表面,并且碳纤维与氧化石墨烯之间形成了化学键,改善了碳纤维的表面结构。实验还对表面处理后碳纤维的力学性能、传导性能以及单丝层间剪切性能做了测试,发现：1)碳纤维表面生长碳纳米管后其拉伸强度减小了5.7%,碳纤维复合材料的单丝层间剪切强度提高了46.0%；2)碳纤维表面接枝碳纳米管后其单丝层间剪切强度提高了49.2%；3)碳纤维表面接枝氧化石墨烯后其拉伸强度提高了9.8%,断裂伸长率提高了13.1%,单丝层间剪切强度提高了97.2%,说明样品经表面处理后其力学性能和层间性能得到提高。更多还原

【Abstract】 Carbon fiber (CF) is the carbon content in more than 90% of inorganic fiber, and by the compound process of resin matrix composite materials performance, had been widely used in aerospace, missiles and civilian areas. Mechanical properties of carbon fiber composites is closely related to the interface shear strength of carbon fiber and matrix, the surface of the untreated carbon fiber inertia big, weak interface bonding to the resin. The low shear strength and bending strength of the composite material affected the performance of carbon fiber composite material, so the carbon fiber was often for surface treatment. The purpose of this study:The surface of carbon fiber was treated by a variety of methods, to improve the mechanical properties and the interlaminar shear strength of the carbon fiber composite material. Carbon nanotubes, graphene has been the focus of the carbon materials research, which have excellent physical, chemical properties, and rich active functional groups can be got by processing and good dispersion. Through the carbon fiber surface processing, could significantly improve the interface bonding strength of carbon fiber and matrix resin.First of all, this article adopted continuous production of growth carbon nanotubes the carbon fiber surface for the carbon fiber surface modification, the method:The carbon nanotubes could be growth by chemical vapor deposition method in the carbon fiber surface. In this paper, after a detailed discussion and a large number of experimental studies, we determined the best continuous process:the use of low temperature combustion method to deal with the resin on the carbon fiber, choose ferrocene as catalyst, xylene as solvent; Choose 750℃, nitrogen purging, control the proportion of carbon and nitrogen gas; Carbon fiber wire walking speed is 8 m/h, carbon fiber through the quartz tube in a row, to achieve continuous growth of carbon nanotubes. SEM and HRTEM were used to characterize the obtained product. A layer of 20-100 nm in diameter, length is 2-5 um carbon nanotubes can be observed on the carbon fiber surface.A kind of carbon fiber/graphene oxide and carbon fiber/carbon nanotubes multi-scale reinforcement was prepared by "grafting to" method.1) the mechanism of the carbon fiber surface grafting carbon nanotubes as:we used ethylenediamine as intermediates, hydrothermal method, the acidification of carbon nanotubes grafted to the processing of carbon fiber; In this paper, after detailed experiment and discussion to determine the best technology of carbon fiber surface grafting carbon nanotube is:we took acid oxidized carbon nanotubes 0.03 g, In accordance with the carbon nanotubes:N, N-dimethyl formamide as 1 (g):the ratio of 1000 (ml), add 30 MLDMF in hot water kettle, in which a certain amount of ethylenediamine again, and then mixed solution under the condition of ultrasonic ultrasonic dispersion 1 h, adding carbon fiber to hot water kettle,180℃ reacted for 48 h, got the carbon fiber/carbon nanotubes multi-scale reinforcement.2) carbon fiber surface grafting graphene oxide:Silane coupling agent KH550 was used to deal with T300 carbon fiber surface which was used acid oxidation treatment, then put the carbon fiber in the graphene oxide which was prepared by improved Hummers method, through the heat treatment the graphene oxide would be grafted to the surface of carbon fiber surface. The structure and the functional groups of the carbon fiber surface was analyzed, we could find that graphene was coating on the surface of the carbon fiber by chemical bond, which improves the surface of carbon fibers, and the crystallite size decreases on the surface of the carbon fiber.The mechanical properties,the conductive and the interlaminar shear strength of carbon fiber reinforced resin matrix composites was also tested and analyzed, find that:1) the tensile strength of the carbon fiber surface after the growth of carbon nanotubes is reduced by 5.7%, the interlaminar shear strength of the composite material is increased by 46.0%;2) the interlaminar shear strength of the carbon fiber surface after grafting carbon nanotubes is increased by 49.2%; 3) the tensile strength of carbon fiber grafting graphene oxide is increased by 9.8%, the elongation at break is increased by 13.1%, the interlaminar shear strength is increased by 97.2%. The mechanical performance of the carbon fiber is improved after surface treatment.更多还原