碳纤维表面可控接枝聚合改性及其复合材料界面模拟研究

发布时间：2018-02-28 23:17

本文关键词： 碳纤维多尺度增强体活性自由基聚合界面分子模拟　出处：《南昌航空大学》2017年硕士论文　论文类型：学位论文

【摘要】：碳纤维增强树脂基复合材料(carbon fiber reinforced polymer composites,CFRP)具有高的比模量和比强度、可设计性好等优点,被广泛应用于航天航空、武器装备等军用领域以及汽车、体育用品、建筑材料等民用领域。但由于碳纤维需要在惰性气氛中经过高温石墨化处理,使得碳纤维表面活性基团少,惰性大,因此与树脂基体的浸润性以及粘接性较差,界面处容易出现破坏,严重影响复合材料的整体性能的发挥以及使用寿命。本文首先通过活性自由基聚合法在碳纤维表面引入梳型聚合物以制得梳型聚合物/碳纤维多尺度增强体,然后以环氧树脂为基体,制得多尺度增强体/环氧树脂复合材料,并对得到复合材料力学性能及界面性能进行表征,研究梳型聚合物的引入对复合材料性能的影响。同时,通过分子模拟构建复合材料模型,从界面能角度研究碳纤维多尺度增强体对复合材料界面的影响。具体完成内容如下:(1)通过丙酮-硝酸法和硅烷偶联剂(KH550)的水解缩合反应对原始碳纤维(CF-Raw)进行表面预处理,得到硅烷偶联剂接枝碳纤维(CF-KH550),然后通过酯化反应将链转移剂锚固到碳纤维表面;最后,通过可逆加成-断裂链转移聚合(RAFT)以及原子转移自由基聚合将梳型聚合物(poly(4-vinylbenzyl chloride-g-glycidyl methacrylate),P(VBC-g-GMA))接枝在碳纤维表面,制得梳型聚合物接枝碳纤维多尺度增强体(CF-P(VBC-g-GMA))。通过傅里叶红外吸收光谱仪(FT-IR)、综合热分析仪(TGA)、X射线光电子能谱(XPS)等对得到的碳纤维多尺度增强体进行表征,结果表明梳型聚合物成功接枝在碳纤维表面,且接枝率为26.37%,场发射扫描电子显微镜(FE-SEM)观察结果表明CF-P(VBC-g-GMA)表面被聚合物包覆,氧化过程中造成的凹槽被修复。(2)以不同改性阶段的碳纤维为增强体,双酚A型环氧树脂(E-51)为基体,三乙烯基四胺(TETA)为固化剂,通过热压工艺制备出复合材料。对得到的复合材料的力学性能进行表征,结果表明:梳型聚合物的引入可明显改善复合材料的力学性能和界面性能,与未改性碳纤维增强复合材料相比,CF-P(VBC-g-GMA)的单丝拉伸强度和复丝拉伸强度分别升高22.00%和14.25%;复合材料的弯曲强度提升23.70%;层间剪切强度(ILSS)提升了31.29%。而界面剪切强度(IFSS)则更是提高了101.88%。场发射扫描电镜结果显示,CF-Raw/环氧树脂复合材料断口处纤维拔出较多,且被拔出的纤维表面光滑,而CF-P(VBC-g-GMA)/环氧树脂复合材料的断口仅有少量的纤维被拔出,且拔出纤维的表面黏附有大量基体树脂,表明CF-P(VBC-g-GMA)与树脂间的黏附作用增强,界面强度提高。(3)借助Materials Studio(MS)构建复合材料模型,从原子尺度出发研究界面层对复合材料强度的影响。以Forcite为运算环境进行分子力学计算,完成结构的几何优化;在NVT系综,Universal力场中进行分子动力学计算。结果表明,复合材料中对界面能变化贡献最大的是体系的交互作用,CF-P(VBC-g-GMA)/环氧树脂复合材料体系中界面处碳纤维与树脂的间距为16.84?,比CF-Raw/环氧树脂复合材料体系降低了23.42%。界面结构中间距减小,碳纤维与树脂间的相互作用增强,复合材料的界面强度增强,宏观力学强度提高。
[Abstract]:Carbon fiber reinforced resin matrix composites (carbon fiber reinforced polymer composites, CFRP) has high specific modulus and specific strength, flexibility in design and is widely used in aerospace, weapons and equipment such as military field and automobile, sports goods, civil building materials. But because of the carbon fiber after high temperature graphitization treatment in an inert atmosphere, the surface of activated carbon fiber group, inert, so the resin and the wettability and adhesion at the interface is poor, prone to failure, seriously affect the overall performance of the composite material of the play and life. Firstly, through the activity of free radical polymerization on the surface of carbon fibers by comb polymer to prepare comb polymer / carbon fiber multi scalereinforcement, then with epoxy resin as matrix and preparation of multi-scale reinforcement / epoxy resin composite material, and the The mechanical properties of the composites and interfacial properties were characterized by introducing the research of comb polymers on the properties of the composite materials. At the same time, through the construction of molecular simulation model of composite material, carbon fiber can enhance the multi-scale study angle influence on the composite interface from the interface. The concrete contents are as follows: (1) by acetone - nitrate method and silane coupling agent (KH550) hydrolysis and condensation reaction of the original carbon fiber (CF-Raw) was pretreated by silane coupling agent grafted carbon fiber (CF-KH550), and then the chain transfer agent anchored to the surface of carbon fiber by esterification; finally, addition fragmentation chain transfer polymerization by reversible (RAFT) and the atom transfer radical polymerization will comb polymer (poly (4-vinylbenzyl chloride-g-glycidyl methacrylate), P (VBC-g-GMA)) was grafted on the surface of carbon fiber, preparation of comb polymer grafted carbon fiber scales increase Strong body (CF-P (VBC-g-GMA)). By means of Fourier transform infrared absorption spectrometer (FT-IR), thermogravimetric analyzer (TGA), X ray photoelectron spectroscopy (XPS) on multi scale carbon fiber reinforcement were obtained, results showed that comb polymer was successfully grafted onto the carbon fiber surface, and the grafting rate was 26.37%, field emission scanning electron microscopy (FE-SEM) observation results showed that CF-P (VBC-g-GMA) surface was coated with polymer, resulting in groove oxidation process was repaired. (2) with different modification stages of carbon fiber as reinforcement, bisphenol A type epoxy resin (E-51) as matrix, three vinyl amine (TETA) four as curing agent, were prepared by hot pressing process of composite material were characterized, on the mechanical properties of composites. The results showed that the addition of comb polymer can significantly improve the mechanical properties and interfacial properties of the composites, and the unmodified carbon fiber reinforced composite material compared to CF -P (VBC-g-GMA) monofilament and multifilament tensile strength tensile strength were increased by 22% and 14.25%; the flexural strength of the composites increased by 23.70%; the interlaminar shear strength (ILSS) and 31.29%. to enhance the interfacial shear strength (IFSS) is improved by 101.88%. field emission scanning electron microscopy showed that CF-Raw/ epoxy resin composite fiber fracture pull out more, and pulled out the fiber surface is smooth, and the CF-P (VBC-g-GMA) / epoxy resin composite material fracture is only a small amount of fiber is pulled out, and pull out the surface of the fiber is adhered with matrix resin, showed that CF-P (VBC-g-GMA) and enhance the adhesion between the resin, the interface strength is increased. (3) with Materials Studio (MS) to construct the composite material model, the atomic scale study of interface layer on the strength of composite materials. The effects of using Forcite as the computing environment for molecular mechanics calculation, the geometric structure. ; in the NVT ensemble of molecular dynamics calculation of Universal force field. The results show that the composite material on the interface can change the largest contribution to the interaction system, CF-P (VBC-g-GMA) / epoxy resin composites interface between carbon fiber and resin at 16.84? CF-Raw/, ratio of epoxy resin composite material the system reduces the reduced spacing 23.42%. interface structure, enhance the interaction between carbon fibers and resin, enhance the interfacial strength, improve the mechanical strength.

【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332

【参考文献】