碳纳米管改性碳纤维/环氧树脂复合材料的制备与性能研究PreparationandPropertiesofCarbonNanotubesModifiedCarbonFiber/EpoxyComposites学科专业：材料学研究生：董留兵指导教师：侯峰副教授天津大学材料科学与工程学院二零一三年十一月独创性声明本人声明所呈交的学位论文是本人在导师指导下进行的研究工作和取得的研究成果，除了文中特别加以标注和致谢之处外，论文中不包含其他人已经发表或撰写过的研究成果，也不包含为获得 天津大学 或其他教育机构的学位或证书而使用过的材料。与我一同工作的同志对本研究所做的任何贡献均已在论文中作了明确的说明并表示了谢意。学位论文作者签名： 签字日期： 年 月 日学位论文版权使用授权书本学位论文作者完全了解 天津大学 有关保留、使用学位论文的规定。特授权 天津大学 可以将学位论文的全部或部分内容编入有关数据库进行检索，并采用影印、缩印或扫描等复制手段保存、汇编以供查阅和借阅。同意学校向国家有关部门或机构送交论文的复印件和磁盘。（保密的学位论文在解密后适用本授权说明）学位论文作者签名： 导师签名：签字日期： 年 月 日 签字日期： 年 月 日摘 要碳纤维/环氧树脂复合材料具有优异的机械性能，被广泛应用在各个领域。然而，环氧基体自身的性能不高以及碳纤维与环氧基体之间弱的界面结合限制着该复合材料的整体性能；对于层状的碳纤维/环氧树脂复合材料，还存在着层间性能较差的问题。随后，纳米尺度的碳纳米管（Carbon nanotubes, CNTs）因其良好的力学、电学性能等被用于碳纤维/环氧树脂复合材料的改性中。本文从优化CNTs在碳纤维/环氧树脂复合材料中的组织形态角度出发，创新性地将冷冻干燥工艺引入到不同碳纤维织物增强的复合材料制备中。具体地，在二维碳纤维织物体系下，讨论了利用冷冻干燥技术在二维碳纤维织物/环氧树脂复合材料中制备连续CNTs网络的可行性。表明：在二维碳纤维织物中，通过冷冻干燥技术，能够把一定量的CNTs组装成连续、多孔的CNTs网络，基于网络结构的稳健性，这些网络大部分能够被保存在复合材料中，从而显著提高复合材料的层间导电性能，并影响着材料层间剪切强度的大小。在一维碳纤维织物体系下，通过选择未经修饰的或羟基化的CNTs、并利用干燥方法控制其在预制体中的分布形貌，系统地讨论了具有不同组织形态和特性的CNTs对复合材料层间性能的影响。表明：相对于直接加热得到的零散分布和团聚体并存的CNTs组织形态，冷冻干燥制得的CNTs网络显著提高了复合材料的层间电导率；羟基化CNTs网络使得相应的复合材料获得了最高的电导率值；未经修饰的CNTs网络有利于复合材料层间剪切强度的提高，但羟基化CNTs网络在提高材料弯曲强度和模量的同时，降低了材料的层间剪切强度。此外，对由冷冻干燥制得的连续CNTs网络的形成机理也进行了研究，其机理可被描述成“限域条件下的冷冻干燥”。在三维碳纤维织物体系下，研究了不同的干燥方法在CNTs改性的三维碳毡/环氧树脂复合材料制备过程中的效果。表明：相对于目前普遍采用的直接加热干燥方法，冷冻干燥的采用有利于保持三维碳毡的原始结构而不产生开裂、有利于改善CNTs在织物中的分散效果，从而显著提高了复合材料的电导率及其弯曲强度。关键词：碳纳米管 碳纤维/环氧树脂复合材料 冷冻干燥 碳纳米管网络ABSTRACTCarbon fiber/epoxy composite exhibits good mechanical properties, and hasobtained applications in many realms. However, the properties of epoxy matrix aremodest and the interfacial strength between fiber and matrix is relatively weak. Theyare considered to be fatal bottlenecks constraining the further improvement of overallproperties of composite. Besides, interlaminar performances of laminate compositeare poor. Then, as nano-scale material, carbon nanotubes (CNTs) were utilized tomodify carbon fiber/epoxy composite, due to their outstanding mechanical andelectrical properties.In the present work, freeze drying method was innovatively used for thepreparation of CNTs modified carbon fiber/epoxy composite from the point ofoptimizing CNT dispersion state in composite. Specifically，In two-dimensional carbon fiber fabric/epoxy composite, the feasibility ofpreparing continuous CNT networks using freeze drying method was discussed. Theresults demonstrated that: CNTs could be assembled to continuous and porous CNTnetworks in fabric with the assist of freeze drying technique. Most part of them werepreserved in composite due to the robustness of network structures, thus significantlyimproved through-thickness electrical conductivity of composite and had an effect oninterlaminar shear strength (ILSS).In unidirectional carbon fiber fabric/epoxy composite, the effect of CNTs withdifferent organization forms and characteristics on through-thickness properties ofcomposite was studied. Different drying methods of heat drying and freeze dryingwere utilized to affect CNT organization form. CNT characteristic was controlled bychoosing different solutions of non-functionalized CNTs (NOCNTs) or hydroxylmodified CNTs (OHCNTs). As a consequence, CNT networks modified compositedisplayed significantly better electrical performance than composite with CNTaggregates; NOCNT networks made the corresponding composite possess higherILSS value, whereas OHCNT networks impaired ILSS while enhancing flexuralstrength and modulus of composite. Beside, the formation mechanism of CNTnetworks was discussed, and could be described as “freeze drying within confinedspace”.In three-dimensional carbon fiber fabric (carbon fiber felt)/epoxy composite, theeffect of different drying methods, including heat drying and freeze drying, oncomposite was studied. The results indicated that compared to the commonly usedheat drying method, freeze drying method exhibited an advantage of keeping originalmacro-structure of the felt and ameliorating CNT dispersion state. Accordingly, theconductivity and flexural strength of the composite fabricated by freeze drying weresignificantly better than the composite fabricated by heat drying method.KEYWORDS: Carbon nanotubes, Carbon fiber/epoxy composite, Freeze drying,Carbon nanotube networksI目 录第一章绪论.11.1 引言.11.1.1 碳纤维/环氧树脂复合材料简介.11.1.2 环氧树脂/碳纳米管复合材料简介.21.1.3 碳纳米管改性碳纤维/环氧树脂复合材料简介.41.2 碳纳米管改性碳纤维/环氧树脂复合材料研究现状.51.2.1 碳纳米管改性碳纤维/环氧树脂复合材料的制备流程.51.2.2 碳纳米管改性碳纤维/环氧树脂复合材料制备中存在的问题.71.3 课题的提出.10第二章实验部