【作者】 汤立；

【导师】 何春菊；

【作者基本信息】 东华大学 ， 材料加工工程， 2012， 硕士

【摘要】 由于石油资源日益枯竭以及石油制品生产的非降解塑料引起的环境污染日益严重,研究和开发以天然高分子为原料的新高分子材料已成为本世纪高分子领域的重要课题之一。纤维素是地球上最丰富的天然高分子,具有独特的性质,如无毒、安全、生物可降解性、生物相容性、亲水性、化学稳定性等,且价格低廉。目前,以纤维素为原料的再生纤维素制品如微孔膜和化学纤维已广泛地应用于各个领域。本论文用离子液体1-丁基-3-甲基咪唑氯([Bmin]C1)溶解纤维素,分别制备Fe304、碳纳米管和石墨烯增强再生纤维膜并研究其结构与性能。论文主要分为以下四个部分：(1)磁性复合膜具有广泛的潜在应用,我们首先用刮膜的方法制备出再生纤维素膜,接着以再生纤维素膜作为基体,采用原位共沉淀法将Fe304纳米粒子附着到再生纤维素膜上。扫描电子显微镜和X射线衍射的结果显示,球形的Fe304纳米粒子能均匀分散和固定在再生纤维素膜基体上,Fe304纳米粒子的结构在膜表面保存完好。傅立叶红外光谱表明,Fe304纳米粒子与再生纤维膜之间存在强烈的作用力,这样导致了磁性粒子能在膜表面形成,热重测试显示,随着复合膜中Fe304的摩尔分数从0.01增加到0.5,复合膜在空气环境烧后的残留量从6.8%提高到28.3%。同时复合膜显示出显著的力学强度。原位共沉淀的方法简单、易行,为制备纤维素基复合物提供了很好的途径。(2)碳纳米管的一维管状结构赋予其优异的物理化学性质,在纳米电子器件、复合材料和催化剂等领域具有广阔的应用前景。我们使用溶液共混方法制备出多壁碳纳米管/再生纤维素复合膜,使用了X射线衍射、傅立叶变换红外光谱、扫描电子显微镜和机械测试仪对复合膜的结构和力学性能进行了测试。结果显示,当多壁碳纳米管的填充量为5%(质量分数)时,碳纳米管／再生纤维素复合膜的抗张强度和抗张模量相对于纯纤维素膜分别提高了184%和54%。复合膜的强度和韧性能同时得到提高的原因有：多壁碳纳米管纳米片能均匀分散在再生纤维素基体内,多壁碳纳米管与再生纤维素膜间具有强烈的氢键作用。(3)石墨烯因为具有优异的物理和化学修饰性而得到人们的广泛关注。我们使用简单的溶液共混方法制备出石墨烯／再生纤维素复合膜,使用了X射线衍射、傅立叶变换红外光谱、扫描电子显微镜和力学测试仪对复合膜的结构和力学性能进行了测试。结果显示,当石墨烯的填充量为5%(质量分数)时,石墨烯/再生纤维素复合膜的抗张强度和抗张模量分别提高了137%和95%。复合膜的强度和韧性能同时得到提高的原因有：石墨烯纳米片能均匀分散在再生纤维素基体内,并呈平行排列；石墨烯与再生纤维素膜间具有强烈的氢键作用,同时石墨烯的添加显著提高了复合膜的结晶度。(4)尽管最近几年以石墨烯为基体的材料发展迅速,但是石墨烯填充高分子材料的报道却较少,主要原因是石墨烯纳米片很难以分子尺度分散在高聚物基体中。我们以剥落氧化石墨烯作为骨架,采用层层自组装的方法制备出氧化石墨烯/再生纤维素多层膜。场发射扫面电子显微镜测试结果显示多层膜是层状结构,50层膜的厚度为20μm,则每单层膜的厚度大约为400nm,而且多层膜的表面光滑。这是由于氧化石墨烯以分子尺度均匀分散在再生纤维膜的基体内。同时复合膜中氧化石墨烯的添加,使得再生纤维素膜产生导电性,而且多层膜的电导率层数的增加而增大。更多还原

【Abstract】 With the decreasing amount of the reserved petroleum and increasing amount of pollution caused by the oil-based products, it is urgent and promising to develop bio-based polymer as supplement for the non-degraded synthetic polymers. Cellulose, the most abundant natural polymer in nature, is renewable, biodegradable, and biocompatible. Therefore, increasing attention has been paid to cellulose as an inexhaustible source of raw material to replace petrochemically derived compounds in many applications. Nowadays, the regenerated cellulose products such as membranes and fibers have been widely developed over a series of industry applications.The effect of Fe3O4, carbon nanotubes and graphene on regenerated cellulose composite has been investigated in this thesis. The present work includes four parts as follows:(1) The cellulose was dissolved in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), and the solution was casted and coagulated in a water bath under appropriate conditions. Then magnetic composite films were fabricated by introducing in-situ synthesized Fe3O4 nanoparticles into the wet cellulose films, in which regenerated cellulose (RC) film was used as a matrix and mixture solutions of Fe3+/Fe2+ as precursors. The structure and morphology of the composite films were studied by Scanning electron microscopy and X-ray diffraction. The results indicate that the spherical magnetic Fe3O4 nanoparticles were dispersed uniformly and immobilized in the matrix, and the structure of Fe3O4 are perfect. FT-IR results demonstrate that there are good interactions between cellulose and Fe3O4 in the films, leading to the formation and stabilization of the novel magnetic materials. The thermogravimetric analysis reveals that with an increasing concentration of precursors from 0.01 to 0.5, the content of Fe3O4 nanoparticles in the dried composites films increases from 6.8% to 28.3%. The cellulose composite films show a higher mechanical strength than that of RC films. Therefore, a simple and effective way is provided to prepare the regenerated-cellulose/Fe3O4 composite films that might be used for the production of cellulose-based films.(2) Carbon nanotubes (CNTs) exhibit novel structure-related physical and chemical properties due to their unique one-dimensional tubular structure, and show significant potential applications for electronic devices, composite materials, and catalysts. The structure and mechanical properties of the composite films were investigated by X-ray diffraction, scanning electron microscopy, and mechanical testing, respectively. The results reveal that a significant enhancement of mechanical properties has been achieved, that is,184% improvement of tensile strength and 54% increase of tensile modulus with 5wt.% MWCNTs loading. The simultaneous improvement of strength and toughness could be attributed to the homogeneous dispersion of CNTs in the RC matrix. The comparison between the experimental results and the Halpin-Tsai theoretical prediction indicates that MWCNTs might be randomly distributed in the RC matrix. Meanwhile, it is interesting to note that all the composites films are transparent. The overall mechanical performance of the composites is suitable for further use in some fields which need materials with higher mechanical properties.(3) Graphene has attracted attention because of its remarkable physical properties and chemical functionalization capabilities. We present the preparation of graphene/RC composites through solution blending. The structure and mechanical properties of the composite films were investigated by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and mechanical testing, respectively. A significant enhancement of mechanical properties is achieved, with 137% improvement of tensile strength and 95% increase of tensile modulus with 5wt.% graphene loading. The simultaneous improvement of strength and toughness is due to the uniform dispersion of graphene and alignment of graphene nanosheets in the RC matrix, and the strong interfacial interactions between graphene and RC, as well as the higher crystallinity of the composites compared to the pure RC film.(4) Despite great development with graphene-based materials, the progress of strong and cost-efficient multifunctional graphene-filled polymer composites has few to be made. A key challenge in the preparation of nanoplatelet-filled polymer composites is the ability to realize the nanometer-level dispersion and the planar orientation of nanosheets in polymer matrices. In this report, multilayer films were successfully fabricated by layer-by-layer assembly of regenerated cellulose and exfoliated graphene oxide, in which exfoliated graphene oxide nanosheets were used as the building blocks. Typical field emission scanning electron microscope images demonstrate an ordered arrangement of layers. The thickness of 50 layer film is about 20μm and the film exhibits a high degree of smoothness. This may be attributed to the well-defined layered structure with high degree of planar orientation and nanolevel assemblies of graphene oxide nanosheets in the polymer matrices. The electrical conductivity of the multilayer films shows a remarkable increase with increasing number of layers in the films.更多还原