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纤维素基复合气凝胶材料的制备及性能研究
Alternative Title化学工程
单友娜
Thesis Advisor气凝胶 ; 纤维素 ; SiO2 ; 氧化石墨烯 ; 力学性能
2017-05
Degree Grantor中科院青岛生物能源与过程研究所
Place of Conferral青岛
Degree Discipline气凝胶因其密度低、比表面积高、孔隙率高、热导率低等特点,被广泛应用于特种服装、航天军工、石油石化、建筑节能等多个领域。以天然高分子为原料制备的生物基气凝胶,在具备传统气凝胶特性的同时,又融入自身的优异特性,如良好的柔韧性、可再生性和环境友好性。作为生物质材料之一,纤维素是一种储量丰富的天然高分子材料,以它为原料制备的气凝胶是继无机气凝胶和合成聚合物气凝胶之后的新一代气凝胶,兼具了纤维素材料和传统气凝胶材料的优点。但纯纤维素气凝胶因其自身的结构特点使得其力学强度相对较差,通过与无机纳米材料复合,能够有效改善其力学强度,同时还能够赋予其导电、疏水、阻燃等特性。因此,本论文以纤维素及其衍生物为基础研究对象,通过与不同无机纳米材料复合制备了纤维素基复合气凝胶,并对其力学性能及隔热性能进行了探究。主要研究内容和结果如下: (1)以棉纤维素、低廉且无污染的硅酸钠为原料,LiOH/尿素/水体系为溶剂,采用原位合成的方法在纤维素凝胶骨架中合成SiO2纳米颗粒,经超临界二氧化碳干燥得到SiO2/纤维素复合气凝胶。探究了不同Na2SiO3质量分数、盐酸浓度、纤维素浓度对复合气凝胶结构及性能的影响。实验结果表明,相比于纯纤维素气凝胶,复合SiO2纳米颗粒后气凝胶的比表面积增加了65%,孔径大小降低1倍,压缩强度和弹性模量分别增加3倍和4倍。 (2)以羧甲基纤维素(CMC)为原料,二维氧化石墨烯(GO)纳米片为增强剂,通过硼酸(BA)进行交联,制备了具有优异力学性能的复合气凝胶。通过对传热速率的调控,制备了具有各向同性和各向异性结构的复合气凝胶,并对其力学性能、隔热性能进行了探究。实验结果表明,具有各向同性结构的复合气凝胶,其压缩强度可达110 kPa,是各向异性结构气凝胶轴向的5倍、径向的14倍,其热导率也低于具有各向异性结构气凝胶的轴向与径向上的热导率。同时探究了氧化石墨烯含量对复合气凝胶的力学性能和隔热性能的影响。结果表明,随着GO含量的增加,复合气凝胶的力学性能逐渐提高,当添加5 wt% GO时,复合气凝胶的压缩强度和弹性模量可分别达到349 kPa和1029 kPa,是CMC气凝胶的1.6倍和4.5倍。但是,随着GO含量的增加,复合气凝胶的热导率也呈增加趋势。
Keyword绿色化学
Abstract中文
Other AbstractAerogels are widely used in fields of special garments, aviation and military industry, petrochemical, energy saving building due to its low density, high specific surface area, high porosity and low thermal conductivity. Bio-based aerogels prepared from nature polymers not only possess the characteristics of traditional aerogels, but also integrate with their own excellent properties such as good flexibility, renewability, environmental friendliness. As one kind of bio-materials, cellulose is an abundant biopolymer in nature. As a new generation, cellulose aerogels combine the advantages of cellulose and traditional aerogels. However, pure cellulose aerogels have poor mechanical strength because of their own structure. Combining with inorganic nano-materials not only can improve their mechanical strength, but also endow them with characteristics of conduction, lyophobic, antiflaming and other interesting properties. In this thesis, cellulose and its derivatives were used as research object, combined with different inorganic nanomaterials to prepare cellulose-based composite aerogels, and their mechanical and heat insulation properties were investigated. The main contents and results are as follows: (1) Cotton cellulose was used as raw material, cheaper sodium silicate was used as precursor and LiOH/urea/H2O system was used as solvent for dissolving cellulose. Then composite hydrogels were fabricated via in situ formation of silica in cellulose hydrogel. Finally, composite aerogels were obtained after drying with supercritical CO2. The effect of preparation conditions such as Na2SiO3 mass fraction, HCl concentration and cellulose concentration on structure and properties of composite aerogels were studied. The results show that the specific surface area of composite aerogels is increased by 65%, pore diameter is decreased 1 times, and compressive strength and Young’s modulus are increased by 3 times and 4 times, respectively. (2) Composite aerogels with excellent mechanical property were prepared by using CMC as raw materials, 2D graphene oxide (GO) nano-sheet as reinforcement, boric acid (BA) as cross-linker. By controlling the heat transfer rate, composite aerogels with isotropy and anisotropy structure were prepared, and the mechanical property and heat insulating were studied. The results show that the composite aerogel with isotropy structure has compression strength of 110 kPa, which is 5 times the axial and 14 times the radial of anisotropy structure composite aerogels, and thermal conductivity is lower than those of two directions of anisotropy structure composite aerogels. And the effect of GO content in isotropy composite aerogels on their properties was also discussed. The results show that the mechanical property of composite aerogel increases with the increase of GO content. When GO content is up to 5 wt%, the compressive strength and Young’s modulus of composite aerogels reach 349 kPa and 1029 kPa, respectively, which are 1.6 and 4.5 times that of CMC aerogels, respectively. However, the increased content of graphene oxide in composite aerogels also increases their thermal conductivity.
Department绿色化学催化团队
Date Available2022-06-01
Subtype硕士 ; 学位论文
Language中文
Document Type学位论文
Identifierhttp://ir.qibebt.ac.cn/handle/337004/9972
Collection绿色化学催化团队
Affiliation中科院青岛生物能源与过程研究所
Recommended Citation
GB/T 7714
单友娜. 纤维素基复合气凝胶材料的制备及性能研究[D]. 青岛. 中科院青岛生物能源与过程研究所,2017.
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