【作者】 秦大可；

【导师】 顾嫒娟；

【作者基本信息】 苏州大学 ， 材料学， 2013， 博士

【摘要】 复合材料独有的可设计性和协同效应使之成为继金属、陶瓷和聚合物之后的第四大类材料。纳米复合材料独特的尺寸效应、隧道效应和表界面效应及不同于宏观复合材料的结构和性能，为复合材料的发展注入了新内容。无机纳米纤维/树脂基复合材料是纳米复合材料的重要形式，其性能不仅取决于无机纳米纤维和树脂基体，还与纳米纤维在树脂基体中的分散性及界面结构密切相关。如何在不降低纤维本身性能的基础上，实现无机纳米纤维在树脂基体中良好的分散及界面结合仍然是一个很大的挑战。此外，目前无机纳米纤维的制备还存在成本高、种类有限，不易实现规模制备等问题。本文针对无机纳米纤维/树脂基复合材料领域存在的关键问题，展开以下五个方面的工作。首先，分别以硅酸四乙酯（TEOS）、钛酸四丁酯（TNBT）和正丙醇锆（ZNP）为主要组分通过静电纺丝技术制备了各种电纺复合纳米纤维。考察了这些复合纳米纤维在空气中进行静电纺丝过程和储存阶段的稳定性，并系统研究了电纺复合纳米纤维在上述过程中的形貌、结构及化学变化。研究结果表明，空气中水分与复合纳米纤维的相互作用，会对纤维的最终形貌和性能产生重要影响。因此，在煅烧前保持复合纳米纤维形貌与性能的稳定是低成本、规模制备高质量无机纳米纤维的关键和前提。通过调整复合纳米纤维的组分，能使其在静电纺丝过程中就完成水解和聚合反应，有利于得到稳定性好的复合纳米纤维。这种纤维在标准环境下储存15天仍能保持初纺纤维的形貌，这一特性使其在规模制备和工业化生产方面具有广阔的应用前景。其次，通过对在标准环境下储存一定时间后的复合纳米纤维进行煅烧、浸水等后续处理，研究上述低成本后处理方法对TNBT(HAc)、ZNP(HAc)等复合纳米纤维结构与形貌的影响及其特殊结构的形成机理。结果表明，通过煅烧、浸水等后处理方法不但可以实现表面粗糙氧化钛（TiO2）纳米纤维的低成本制备，而且也可以通过工艺条件的控制得到具有纤维套管（fiber-in-tube）结构的TiO2纳米纤维及纯金红石相实心TiO2纳米纤维。同时，利用TNBT和ZNP在空气中快速水解和聚合的特性，可以在TiO2和氧化锆（ZrO2）纳米纤维表面进行包覆，形成具有核壳（core-shell）结构的纤维。第三，以锆醇盐作为电纺前驱物原料，基于静电纺丝和溶胶-凝胶技术建立了制备化学性能和纤维形貌可控的ZrO2纳米纤维的方法，并制得了ZrO2纳米纤维/氰酸酯基（CE）复合材料。通过标准静电纺丝装置制备的复合纳米纤维在不同温度下煅烧后得到具有孔洞尺寸可调和晶体结构可控的ZrO2纳米纤维及相应纤维聚集体。通过构建这种形貌、结构可控的ZrO2纳米纤维聚集体，使聚集体中纳米纤维间的相对位置在其与树脂基体形成复合材料前后都保持固定，有效地防止纤维间发生团聚。这种纤维聚集体有效地解决了纳米纤维在树脂基体中的分散问题，得到具有优异综合性能的ZrO2纳米纤维/CE基复合材料。第四，设计并制备表面包覆纳米氧化硅（SiO2）颗粒的ZrO2纳米纤维（SiO2@ZrO2）。这种新型纤维表面不仅具有能与CE树脂基体反应的活性基团，而且还有能与CE树脂基体间产生物理作用的特殊形貌。在通过构建纤维聚集体解决纳米纤维在树脂基体中分散问题的前提下，包覆纳米SiO2颗粒的ZrO2纳米纤维有效地改善了与树脂基体间的界面结合。系统考察了SiO2@ZrO2纳米纤维的特殊结构对于SiO2@ZrO2/CE基复合材料性能的影响，建立了上述复合材料体系结构与性能的关系。研究结果表明，通过对ZrO2纳米纤维表面进行纳米SiO2颗粒包覆得到的SiO2@ZrO2纳米纤维，可以与CE树脂基体间形成良好的界面结合，从而获得高性能SiO2@ZrO2/CE基复合材料。第五，首次通过静电纺丝及后续处理制备了钛酸铜钙（CCTO）纳米纤维。系统地研究了静电纺丝前驱物溶液的组分对前驱物溶液粘度及可纺性的影响。通过乙酸（HAc）作为缓冲剂改善前驱物溶液的可纺性，利用静电纺丝技术制备了CCTO复合纳米纤维。探讨了CCTO复合纳米纤维的后处理工艺对最终得到的CCTO纳米纤维结构与性能的影响。制备了CCTO纳米纤维与CE树脂基体的复合材料，并对相应复合材料进行了介电性能测试和计算。结果表明，通过静电纺丝技术制备的高质量纯相CCTO纳米纤维具有与CCTO块体材料不同的介电性能。更多还原

【Abstract】 The excellent designability and synergistic effects make the composites become the fourthindependent category of materials follow-up to the metals, ceramics and polymers. Furthermore,compared with the macroscopic composites, nano-composites have outstanding performancefrom unique dimensional effects, quantum tunneling effects, and surface effects, which canbreathe new life into the field of composites. The inorganic nanofibers/resin matrix composite isthe important part of nano-composites. The performance of nano-composite not only depends onthe inorganic nanofibers and resin matrix, but also is greatly related to nanofibers dispersion andinterfacial adhesion in matrix. However, the manufacture process of high quality inorganicnanofibers is too costly, the sort and production of commercial inorganic nanofibers is limited.Meanwhile, how to keep good dispersion and desirable interfacial bonding of inorganicnanofibers in resin matrix without structural damage of nanofibers is still a challenge. We focuson these problems from inorganic nanofibers/resin matrix composite’s field in this dissertation,and raise five questions about the nano-composites.First, the various electrospun composite nanofibers have been prepared with keycomponents of tetraethyl orthosilicate (TEOS), titanium butoxide (TNBT), or zirconiumpropoxide (ZNP) respectively. Then the chemical and morphological stability of compositenanofibers in the air has been investigated and studied systematically during the electrospinningprocess and storage periods. The results show that moisture in the air will interact with theelectrospun composite nanofibers, and made a significant impact on ultimate morphology andperformance of the nanofibers. Hence, how to remain morphology and chemical properties ofcomposite nanofiber unchanged before the next steps, such as calcination and soak, are the basicrequirements for preparation of inorganic nanofibers with high production at low-cost. Bychoosing components in the electrospun composite nanofibers, the TNBT and ZNP in compositenanofibers can complete reaction of hydrolysis and polymerization during the electrospinningprocess. As the result, the as-spun composite nanofibers have excellent chemical and morphologystability, which can remain their morphology even after stored in the standard environment for15days, showing great potential in the large-scale preparation. Second, the influences of low-cost post-treatment, such as calcination and soak, on thestructure and morphology of electrospun composite nanofibers (TNBT(HAc) and ZNP(HAc)),which use TNBT and ZNP as key components respectively, have been investigated. Theformation mechanism of the composite nanofibers with special structures is worth studying. Theresults of the research show that the low-cost post-treatment can not only prepare titanium oxide(TiO2) nanofibers with rough surface, but also fabricate fiber-in-tube, solid and pure rutile-phasestructure TiO2nanofibers with a few simple steps. Meanwhile, for TNBT and ZNP can quicklyhydrolyze and polymerize in the air, it can be used conveniently to prepare TiO2and zirconiumoxide (ZrO2) nanofibers with core-shell structures by coating hydrolysis and polymerizationproducts from TNBT and ZNP.Third, using zirconium alkoxides as the key components in electrospun precursor materials,ZrO2nanofibers with controllable chemical properties and morphology were prepared by a newmethod based on electrospinning and sol-gel technology. The ZrO2nanofiber/cyanate ester (CE)resin composites with comprehensive properties were prepared by dispersing ZrO2nanofibercongeries in CE resin matrix. Through a standard electrospinning device and muffle, the porousZrO2nanofibers with different pore sizes and crystal structures can be prepared by calcining theelectrospun composite nanofibers at different temperatures. The ZrO2nanofibers congeries fromelectrospinning has a special structure, in which the relative positions of ZrO2nanofibers arefixed during the preparation process of ZrO2nanofiber/CE composites. As a result, theaggregation of ZrO2nanofibers can be avoided, and good dispersion of ZrO2nanofibers in thecan be gotten, leading to form ZrO2nanofiber/CE composites with excellent performance.Fourth, ZrO2nanofibers coated with nano-SiO2particles (SiO2@ZrO2) have been designedand prepared. The SiO2@ZrO2nanofibers not only have surface functional groups which willreact with the CE resin, but also can produce non-chemical mechanical interlocking effectsbetween the nanofibers and CE resin. The influence of SiO2@ZrO2nanofibers on the structureand properties of the SiO2@ZrO2nanofibers/CE composites was studied systematically. Theresults indicate that the SiO2@ZrO2nanofibers can obviously raise the bonding performance ofinterface layers between nanofibers and resin matrix, and consequently, improving performanceof the composite materials.Fifth, the copper-calcium titanate (CCTO) nanofibers have been firstly prepared byelectrospinning technique. The compositions of electrospinning precursor solutions have beencarefully studied. And the CCTO electrospun composite nanofibers have been successfully prepared by adding modifier (HAc) into the precursor solutions. The post-treatment on CCTOcomposite nanofibers has also been examined to distinguish the influence of process parameterson the structure and morphology of CCTO nanofibers. In addition, the dielectric properties ofpure-phase CCTO nanofibers and CCTO/CE composites have been measured and calculated. Theresults show that pure-phase CCTO nanofibers have different dielectric properties from theCCTO bulk materials.更多还原