磁性微胶囊相变材料及聚酰亚胺复合薄膜的合成与表征
发布时间：2019-02-23 17:15
【摘要】：相变材料(PCMs)在相变的过程中能够从环境中吸收或释放热量,起到储存能量和管理温度的作用。而常用的PCMs在相变的过程中会发生固态和液态的转变导致泄漏的发生,因此需要将PCMs进行封装。本文采用微胶囊封装技术对PCMs进行封装。第二章中设计了一种兼具储热功能和磁性功能的双功能微胶囊相变材料(MEPCMs),该MEPCMs以正二十烷为芯材,四氧化三铁/二氧化硅(Fe3O4/SiO2)复合材料为壁材。制备的过程中首先采用Pickering乳液的方法将Fe304纳米粒子(Fe3O4 NPs)自组装到正二十烷液滴的表面,然后引发正硅酸四乙酯(TEOS)在油-水界面处的水解和缩聚反应形成致密的Si02保护层。制得的磁性MEPCMs具有以下特性：(1)表现为完美的球状形貌且具有核一壳结构；(2)由表面至中心的化学成分分别是Si02、Fe304和正二十烷；(3)壁材中的Fe3O4 NPs具有反尖晶石结构,而Si02是无定型的；(4)具有超顺磁性；(5)具有良好的相变性能、热稳定性和耐用性。该磁性MEPCMs具有的双功能特性使得其可应用于调温和防辐射纤维或织物,红外和电磁屏蔽产品或电子芯片的抗干扰涂层等领域。第三章设计了一种兼具温度管理功能和电磁屏蔽功能的聚酰亚胺(PI)复合薄膜。PI复合薄膜的制备采用两步法,首先合成有机硅包覆的磁性MEPCMs,然后将制得的磁性MEPCMs与PI复合。合成有机硅包覆的磁性MEPCMs的过程中首先以聚乙二醇(PEG)为分散相,液体石蜡为连续相,制得油包水的乳液,然后引发甲基三甲氧基硅烷(MTMS)在水-油界面处的水解和缩聚反应生成有机硅的外壳。而制备PI复合薄膜的过程中,首先制备PAA和磁性MEPCMs的粘稠的混合液体,然后将PAA和磁性微胶囊的混合液体流延成膜,在高温下热环化制得PI复合薄膜。磁性MEPCMs和PI复合薄膜具有以下特征：(1)磁性MEPCMs呈现碗形结构,具有完美的核-壳结构,而PI复合薄膜中的磁性微胶囊分布在PI的基体中并被PI基体包围起来；(2)磁性MEPCMs的芯材是PEG/Fe3O4复合材料,壁材是有机硅；(3)磁性MEPCMs具有良好的相变性能和热稳定性,而PI复合薄膜的热稳定性虽然出现了一定程度的下降,但是仍具有优异的热稳定性；(4)制得的PI复合薄膜具有优异的电磁屏蔽效能。综上所述,制得的PI复合薄膜不仅能够起到管理温度的作用,还能够作为电磁屏蔽材料,可广泛的应用于电子设备及其元件的生产与制备。
[Abstract]:Phase change material (PCMs) can absorb or release heat from the environment in the process of phase transition, which plays the role of energy storage and temperature management. However, the transition of solid and liquid state will occur in the process of phase transition of PCMs, so it is necessary to encapsulate PCMs. In this paper, microencapsulation technology is used to encapsulate PCMs. In chapter 2, a dual-function microencapsulated phase change material (MEPCMs),) with both heat storage and magnetic properties was designed. The core material of MEPCMs was n-eicosane, and the Fe _ 2O _ 3 / Fe3O4/SiO2 composite was used as wall material. In the process of preparation, Fe304 nanoparticles (Fe3O4 NPs) were self-assembled onto the surface of n-eicosane droplets by the method of Pickering emulsion. Then the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) at the oil-water interface were initiated to form a dense Si02 protective layer. The obtained magnetic MEPCMs has the following characteristics: (1) perfect spherical morphology and core-shell structure; (2) the chemical composition from the surface to the center is Si02,Fe304 and n-eicosane, respectively. (3) Fe3O4 NPs in the wall has antispinel structure, while Si02 is amorphous, (4) superparamagnetic, (5) good phase change, thermal stability and durability. The dual functional properties of the magnetic MEPCMs allow it to be used in the fields of thermostat and radiation resistant fibers or fabrics, infrared and electromagnetic shielding products, or anti-interference coatings for electronic chips. In chapter 3, a polyimide (PI) composite film with both temperature management and electromagnetic shielding function was designed. The preparation of PI composite film was carried out by two-step method. Firstly, the silicone coated magnetic MEPCMs, was synthesized. Then the magnetic MEPCMs and PI were synthesized. In the process of synthesizing silicon-coated magnetic MEPCMs, water in oil emulsion was prepared by using polyethylene glycol (PEG) as dispersion phase and liquid paraffin as continuous phase. Then the hydrolysis and Polycondensation of methyl trimethoxysilane (MTMS) at the water-oil interface to form an organic silicon shell were initiated. In the process of preparing PI composite film, the viscous mixed liquid of PAA and magnetic MEPCMs was first prepared, and then the mixed liquid of PAA and magnetic microcapsule was formed into film, and the PI composite film was prepared by thermal cyclization at high temperature. The magnetic MEPCMs and PI composite films have the following characteristics: (1) the magnetic MEPCMs has a perfect core-shell structure, and the magnetic microcapsules in the PI composite film are distributed in the PI substrate and surrounded by the PI substrate; (2) the core material of magnetic MEPCMs is PEG/Fe3O4 composite material, and the wall material is organosilicon; (3) the magnetic MEPCMs has good phase transformation and thermal stability, while the thermal stability of PI composite film decreases to some extent, but it still has excellent thermal stability. (4) the PI composite film has excellent electromagnetic shielding efficiency. In conclusion, the prepared PI composite film can not only play the role of temperature management, but also can be used as electromagnetic shielding material, can be widely used in the production and preparation of electronic equipment and its components.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34;TB383.2
本文编号：2429045
[Abstract]:Phase change material (PCMs) can absorb or release heat from the environment in the process of phase transition, which plays the role of energy storage and temperature management. However, the transition of solid and liquid state will occur in the process of phase transition of PCMs, so it is necessary to encapsulate PCMs. In this paper, microencapsulation technology is used to encapsulate PCMs. In chapter 2, a dual-function microencapsulated phase change material (MEPCMs),) with both heat storage and magnetic properties was designed. The core material of MEPCMs was n-eicosane, and the Fe _ 2O _ 3 / Fe3O4/SiO2 composite was used as wall material. In the process of preparation, Fe304 nanoparticles (Fe3O4 NPs) were self-assembled onto the surface of n-eicosane droplets by the method of Pickering emulsion. Then the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) at the oil-water interface were initiated to form a dense Si02 protective layer. The obtained magnetic MEPCMs has the following characteristics: (1) perfect spherical morphology and core-shell structure; (2) the chemical composition from the surface to the center is Si02,Fe304 and n-eicosane, respectively. (3) Fe3O4 NPs in the wall has antispinel structure, while Si02 is amorphous, (4) superparamagnetic, (5) good phase change, thermal stability and durability. The dual functional properties of the magnetic MEPCMs allow it to be used in the fields of thermostat and radiation resistant fibers or fabrics, infrared and electromagnetic shielding products, or anti-interference coatings for electronic chips. In chapter 3, a polyimide (PI) composite film with both temperature management and electromagnetic shielding function was designed. The preparation of PI composite film was carried out by two-step method. Firstly, the silicone coated magnetic MEPCMs, was synthesized. Then the magnetic MEPCMs and PI were synthesized. In the process of synthesizing silicon-coated magnetic MEPCMs, water in oil emulsion was prepared by using polyethylene glycol (PEG) as dispersion phase and liquid paraffin as continuous phase. Then the hydrolysis and Polycondensation of methyl trimethoxysilane (MTMS) at the water-oil interface to form an organic silicon shell were initiated. In the process of preparing PI composite film, the viscous mixed liquid of PAA and magnetic MEPCMs was first prepared, and then the mixed liquid of PAA and magnetic microcapsule was formed into film, and the PI composite film was prepared by thermal cyclization at high temperature. The magnetic MEPCMs and PI composite films have the following characteristics: (1) the magnetic MEPCMs has a perfect core-shell structure, and the magnetic microcapsules in the PI composite film are distributed in the PI substrate and surrounded by the PI substrate; (2) the core material of magnetic MEPCMs is PEG/Fe3O4 composite material, and the wall material is organosilicon; (3) the magnetic MEPCMs has good phase transformation and thermal stability, while the thermal stability of PI composite film decreases to some extent, but it still has excellent thermal stability. (4) the PI composite film has excellent electromagnetic shielding efficiency. In conclusion, the prepared PI composite film can not only play the role of temperature management, but also can be used as electromagnetic shielding material, can be widely used in the production and preparation of electronic equipment and its components.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34;TB383.2
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