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多维结构碳纳米材料的制备及其在复合材料健康检测中的应用
郝斌
学位类型博士
导师马鹏程
2017-05-25
学位授予单位中国科学院大学
学位授予地点北京
学位专业物理化学
关键词碳纳米管 石墨烯 纤维增强复合材料 纤维 健康检测
摘要

各种碳纳米材料,包括碳纳米管(Carbon nanotubes,CNTs)、石墨烯,由于具有优异的电学、力学、光学性能和多样的组装结构,可用于复合材料的健康检测。该方法依据的原理是在外界负载条件下,含有碳纳米颗粒的材料会发生形变,进而引起材料内部导电网络的变化,这与材料的宏观电学性质密切相关。通过检测材料的电学性质(如电阻、电容等),就可以为评价复合材料内部裂纹的产生、扩展等过程提供依据。虽然近年来在上述领域中取得了较大的研究进展,但是该项技术仅用于预测纤维增强复合材料(Fiber Reinforced Polymers,FRPs)内部基体的性质变化。另外,碳纳米颗粒的组装结构与FRPs的复合方式、不同碳纳米颗粒结构和性质差异,都会影响FRPs材料的电学性质。针对上述因素开展的具体研究较少,而相关的比较研究亦鲜有报道。针对上述问题,本研究采用不同方法制备了含碳纳米材料颗粒的组装结构,并将该结构引入到传统的FRPs材料中,通过研究不同条件下材料的力学、电学性质来实现检测FRPs材料健康状况的目的。研究论文包括以下部分:1)以一维玻璃纤维为基底,利用电泳法将CNTs和石墨烯沉积在纤维表面,研究了单根纤维和相应FRPs材料的力学、电学性质。研究发现:CNTs在纤维表面形成松散的网状结构,石墨烯在纤维表面形成致密的层状结构,且含石墨烯的单纤维对应力更加敏感。在相应的FRPs材料中,含石墨烯的玻璃纤维与基体材料界面处形成一层致密的导电层,并可实现材料的导电性能与整体FRPs断裂行为同步;而含CNTs的玻璃纤维与基体的界面处形成CNT/高分子纳米复合材料结构,导电涂层的完全破坏远早于FRPs材料的整体断裂。2)针对单根纤维制备过程中存在的步骤繁琐等问题,采用二维纤维束为基底,利用化学气相沉积法在玄武岩纤维表面分别生长CNTs和热解碳,开展二者在复合材料健康检测方面的对比研究。研究结果表明:通过控制实验条件可在纤维表面高效、可控地生长出CNTs或热解碳。含CNTs和热解碳涂层的纤维束在FRPs材料承受负载的条件下电阻行为区别显著:含 CNTs的FRPs电阻变化是以“直台阶”上升方式进行,而含热解碳的FRPs其电阻呈现出“斜台阶”上升方式。这主要是因为含CNTs的纤维表面与基体形成纳米复合材料结构,可以被迅速破坏;而含有热解碳的纤维表面光滑,与基体相互作用较弱,可在更大的应变条件下维持FRPs材料的整体导电性。3)以高分子泡沫为模板,制备了具有三维泡沫结构的CNTs材料,实现了高分子模板的部分去除、催化剂原位形成和CNTs可控生长同步进行。以此具有层级结构的三维泡沫材料为核心制备了基于高分子纳米复合材料体系的柔性应变传感材料和器件。该器件可以在保持较高的敏感度因子情况下,实现对较高拉伸应变和压缩应变的检测(均可达到50%以上),并从微观形貌和结构变化角度上对传感材料的力学和电学行为进行了解释,表明该材料在柔性应变传感方面具有很大的应用潜力。4)对不同维度的碳纳米材料组装结构在复合材料健康检测领域的结果进行了对比说明:含一维单根纤维的样品在拉伸过程中电阻增大,导电性在应变较小的情况下就会失去,仅能用于FRPs材料早期健康预测;含准二维束纤维样品在拉伸过程中电阻变化可以体现出单根纤维断裂的结果,导电性几乎可以保持至FRPs材料完全破坏之时;三维的CNT泡沫则是在较大的拉伸和压缩应变情况下电阻均有响应,并具有很好的循环稳定性,这在一维和二维组装结构中较难实现。

其他摘要

Carbon-based nanomaterials, such as carbon nanotubes (CNTs) and graphene, have attracted much interest for monitoring health states of composites due to their excellent electrical, optical properties as well as the diversity for structural assembly. The principle of such application is mainly based on the the monitoring of resistance of composites, which originates from the deformation of conductive networks in composites under external load. The variation on the electrical singals of material could give information on structural damages in composites, such as the initation and propagation of cracks. While numerous reports have been released so far, one of the major limitations of such techniques is that one can not evaluate the health state of fiber, which actually sustains the majority of load in composites. In addition, issues arising from structural assembly and differences of nanoparticles, the way of incoperating nanomaterials into fiber-reinforced polymers (FRPs), are not considered systematically, which severely affect the electrical properties of composites. This dissertation is dedicated to study the feasibility of assembly structures arising from carbon nnaomaterials for monitoring health states of FRPs. Multi-dimensional structures were prepared and incorporated into FRPs to achieve our research goals. Major contents were described as follows: 1) CNTs and graphene were deposited on the surface of glass fibers (GFs) using an electrophoretic deposition method, and the electrical and mechanical properties of single fiber and corresponding FRPs were studied. The results showed that different structures of conductive networks were formed on fiber surface: CNTs distributed randomly on GFs and connected each other by a point-to-point mode, whereas graphene formed layer-by-layer coating with a full coverage for GFs. Graphene-GFs showed a higher sensitivity to mechanical strain than that of CNT sample thanks to the tight layer structure formed on fiber surface. Moreover, such structure was remained in Graphene-GFRP, and can be sustainable for electrical conductivity until complete failure of FRPs. Whereas the CNT-GFRP sample turned into non-conductive early before the total failure of FRPs, in which the interphase was polymer nanocomposite consisting of CNTs and polymer matrix. 2) Chemical vapor deposition (CVD) method was adopted to treat basalt fiber (BF) yarns, creating CNT networks or a thin layer of pyrolytic carbon (PyC) coating on fiber surface with two-dimentional sturctures. The generation of CNTs was due to the presence of metal elements on fiber surface. Model FRPs were prepared by employing fiber yarn and epoxy resin as polymer matrix. Resistance change (ΔR/R0)-strain curve of PyC-BFRPs showed an interesting “tilted-steps”, indicating one after another failure of individually conductive fibers in composites, whereas CNT-BFRPs exhibited a suddenly jumping behavior in electrical resistance because of the dissimilarities in conductive layer structure. 3) CNT foam based on the backbones of three dimensional polymer foam was prepared by taking melamine-formaldehyde sponge as a template via CVD process. The method integrated the removal of polymer template, generation of metal catalyst and growth of CNTs into one process, making the method highly effective to achieve scale-up production of CNT foam. The foam, possessing porous structure, high conductivity and hydrophobic properties, was incorporated with polydimethylsiloxane (PDMS) to prepare nanocomposite sensor. The sensor showed the capability to be sensitive under both compression and tension states in a large strain range as high as above 50%. The operating principles of sensor were closely correlated with deformation of foam skeletons in nanocomposites, including angles around joints, struts length as well as crack initiation and propogation. The outstanding sensitive performance and stability of nanocomposite sensor demonstrated its great potential for applications in wearable and flexible electronic devices. 4) Comparison on performance among different assembly structures of carbon-based nanomaterials was conducted in the corresponding parts in above. In single fiber composites, resistance was increased with tension strain and the electrical properties in CNT case could not be sustained in the whole process. In fiber yarn composites, behavior of single fiber breakage was available from resistance change under tension and the conducting networks could be almost sustained in the whole process. In CNT foam composites, resistance increase could be detected in large range under both compressive and tensile strains, which was different from the cases of fiber and fiber yarn composites

文献类型学位论文
条目标识符http://ir.xjipc.cas.cn/handle/365002/4975
专题环境科学与技术研究室
作者单位中国科学院新疆理化技术研究所
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郝斌. 多维结构碳纳米材料的制备及其在复合材料健康检测中的应用[D]. 北京. 中国科学院大学,2017.
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