【作者】 王双双；

【导师】 张忠平；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2011， 硕士

【摘要】 能源问题是制约经济发展的瓶颈,对于新型能源和节能技术的研究得到了人们的重视,相变储能技术可用于解决能源在供求时间上的不匹配,相变材料由于具有储能和控温能力,成为储能技术研究的热点。有机相变材料不存在过冷和相分离的问题,且相变潜热较大,但是热导率低和固-液相变时发生液体泄漏是存在的主要问题,本论文结合纳米技术,研究相变材料纳米尺度下的热学行为,有效解决了有机相变材料在相变储能中存在的问题。本论文以十八烷酸为研究对象,制备了不同形貌的十八烷酸结构,提高了其热学性质。(1)利用模板作用制备了不同形貌的十八烷酸的纳米结构,实验中未引入其他的物质,避免了基体对热学测试的影响,单独研究纳米尺度下的十八烷酸热学性质的变化。实验制备了不同形貌的十八烷酸纳米结构,六方片、四方片、团簇、树枝、纳米线等形貌,通过SEM、EDS、FT-IR、XRD对其进行了表征。纳米化的十八烷酸与传统的十八烷酸相比,热学性质有所变化,DSC数据表明纳米化后的相变温度略有降低,但有的也有所升高;热导数据表明纳米化后的热导率有所提高。(2)制备了芯-壳结构的二氧化硅包覆十八烷酸的纳米胶囊,可以有效解决固-液相变时发生液体泄漏的问题。实验利用微乳液的方法,形成水包油型微乳液,然后加入苯基三甲氧基硅烷,利用水解-缩合作用包覆在十八烷酸的表面,形成芯-壳结构的纳米胶囊。利用SEM、TEM、FT-IR、XRD等进行了表征,对纳米胶囊进行了热学性质的测试,DSC数据表明纳米胶囊比传统的十八烷酸熔化温度升高了15℃,凝固温度升高了12℃,但是热焓值并没有减小。对不同的实验条件进行了研究,研究了不同芯-壳的配比、不同水解和缩合时间、不同温度等对纳米胶囊的影响,得出最佳的实验条件。更多还原

【Abstract】 Energy crisis is the bottleneck of restricting economic development, so the study for new energy resources and energy saving technology got the attention of people, energy storage technology with phase change materials can be used to solve the supply and demand of energy which does not match in with time, phase change materials can store energy and control temperature, which make they become the research hot spot on energy storage technology. Organic phase change materials do not existed supercooling and phase separation problems, and they have high latent heat, but low thermal conductivity and liquid leakage is the main problem of organic phase change materials. We make use of the nano technology in this paper, it effectively resolved the existed problems of organic phase change materials in store energy process. We chose the octadecanoic acid as the research object, we prepared different morphologies of octadecanoic acid in nanometer scale and core-shell nanocapsule structure. The thermal performance of phase change materials under the nanometer scale was enhanced.(1) We use the template method to prepare nano structure octadecanoic acid with different morphologies, without other materials, avoiding the thermal test influence of matrix, we can independently study the thermal properties of octadecanoic acid in the nanometer scale. We synthesized several different morphologies of octadecanoic acid, such as hexagonal piece, square piece, cluster, branche and nanowire, the properties of the nano octadecanoic acid were characterized by SEM, EDS, FT-IR and XRD. From the thermal results, we compared the nano octadecanoic acid to the traditional octadecanoic acid, thermal properties were changed. DSC data showed that the phase transition temperature after nanometer was slightly lower, but some were higher; Thermal conductivity data showed that the thermal conductivity was improved in nanometer scale.(2) We prepared core-shell octadecanoic acid nanocapsule which was encapsulated by silica, the nanocapsule structure can effectively solve the leakage problem when liquid-solid phase change process occurs. We use the micro emulsion method to prepare the core-shell structure, firstly, the materials were formed into oil in water microemulsion, and then PTMS was added into the microemulsion dropwisely, the hydrolysis and condensation procedures occurred on the surface of octadecanoic acid, finally octadecanoic acid was wrapped by silica, the core-shell nanocapsul was synthesized successfully. The nanocapsule was analyzed by SEM, TEM, FT-IR, XRD, and the thermal properties were tested by DSC tester, DSC results showed that melting temperature and solidification temperature of nanocapsule increased 15℃and 12℃respectively than traditional octadecanoic acid, but the thermal enthalpy didn’t decreased. We study the influence to the nanocapsule of different experimental conditions, different core-shell ratio, different hydrolysis and condensation time, different temperature, which obtains the best experimental conditions.更多还原