纳米纤维膜负载脂肪酸定形相变材料的结构与性能
发布时间：2018-08-28 06:05
【摘要】：能源的合理利用和新能源的开发一直是人们关注的焦点,欲缓解能源紧缺、能源消费快速增长与环境污染之间的诸多矛盾,利用相变材料的相变潜热进行能量的存储与释放是一项新型环保节能技术,可以以此来控制体系或环境的温度,具有热能储存和温度调控的功能。脂肪酸是一类重要的固-液相变材料,具有储热密度大、相变过程温度恒定等优点而备受关注,但存在相变体积变化大和热传导性低等缺点。然而,静电纺无机纳米纤维具有较高的比表面积、独特的网络结构、丰富的孔隙率和高的热传导系数等优异特点可用作固-液相变材料的支撑材料,有效解决了脂肪酸相变过程的渗漏现象和低的热传导性问题。因此纳米纤维膜负载脂肪酸定形相变材料的制备与结构性能研究成为重要的研究方向。本文以癸酸(CA)、月桂酸(LA)、肉豆蔻酸(MA)、棕榈酸(PA)和硬脂酸(SA)为原料,利用熔融混合和超声分散的方法制备了CA系二元脂肪酸低共熔物(CA-LA,CA-MA,CA-PA和CA-SA)和CA-LA-PA三元脂肪酸低共熔物,并用作相变材料。结合溶胶-凝胶、静电纺丝和高温煅烧等原理与技术,制备了Si O2纳米纤维和Ti O2掺杂Si O2(Ti O2/Si O2)纳米纤维,并用作支撑材料。然后利用纳米纤维膜物理吸附脂肪酸的方法制备了复合定形相变材料,对其结构形貌和性能进行了研究。其主要研究内容可分为以下三部分:1.制备了PVP/Si O2复合纳米纤维,利用TGA研究了其热降解过程,然后经500oC、600oC和700oC三种不同温度煅烧处理,制得Si O2纳米纤维,采用FT-IR对其组成成分和官能团变化进行了表征,证实了Si O2纳米纤维的形成。对比分析了不同煅烧温度下Si O2纳米纤维对亚甲基蓝染料和CA-LA-PA三元脂肪酸低共熔物的吸附性能,结果表明经600oC煅烧制得的多孔网络结构Si O2纳米纤维具有较高的吸附容量。2.利用XRD和SEM对Si O2纳米纤维的结构形貌进行了进一步的表征,结果显示Si O2纳米纤维具有无定形的结构,且纤维表面粗糙、部分地方出现粘连。通过SEM、吸附性能、DSC及自组装热性能测试仪对制备的Si O2基复合定形相变材料的形貌结构、吸附容量、储热性能及热能储存/释放性能进行了研究,结果表明二元脂肪酸低共熔物较好的分散在Si O2纳米纤维的多孔网络结构中,归因于脂肪酸与Si O2之间的毛细管效应和表面张力作用。同时,复合定形相变材料具有适宜的相变温度和较高的热焓值,且静电纺Si O2纳米纤维改善了复合定形相变材料的热能储存/释放速率。3.以钛酸正丁酯(TBT)和正硅酸四乙酯(TEOS)为前驱体,通过静电纺丝和高温煅烧制备了Ti O2掺杂Si O2(Ti O2/Si O2)纳米纤维。采用FT-IR、XRD和SEM对三种煅烧温度(600oC、900oC和1200oC)下制得Ti O2/Si O2纳米纤维的成分、晶型结构和形貌进行了表征,结果显示随着煅烧温度的升高,Ti O2/Si O2纳米纤维由600oC时的无定形结构转变为1200oC时的晶型结构,纤维的形貌也由600oC时的均匀且表面光滑的圆柱形变为1200oC时的钙化状。此外,通过SEM、吸附性能和DSC对不同热处理温度下制得Ti O2/Si O2基复合定形相变材料的形貌结构、吸附容量和热性能进行了对比研究,研究结果表明二元脂肪酸低共熔物较均匀地分散在Ti O2/Si O2纳米纤维的多孔网络结构中,随着煅烧温度的升高,Ti O2/Si O2纳米纤维的结构形貌变化致使其对二元脂肪酸低共熔物的吸附容量下降,导致复合定形相变材料的热能存储性能降低。
[Abstract]:The rational use of energy and the development of new energy sources have always been the focus of attention. In order to alleviate the contradiction between energy shortage, rapid growth of energy consumption and environmental pollution, the use of latent heat of phase change materials for energy storage and release is a new environmental protection and energy-saving technology, which can be used to control the temperature of the system or environment. Fatty acids are a kind of important solid-liquid phase change materials, which have the advantages of high heat storage density and constant temperature during phase change process. However, they have the disadvantages of large phase change volume change and low thermal conductivity. However, electrospun inorganic nanofibers have high specific surface area and unique network junction. Structures, abundant porosity and high thermal conductivity can be used as support materials for solid-liquid phase change materials, which can effectively solve the leakage and low thermal conductivity problems in fatty acid phase change process. CA binary fatty acid eutectics (CA-LA, CA-MA, CA-PA and CA-SA) and CA-LA-PA ternary fatty acid eutectics were prepared by melt mixing and ultrasonic dispersion using decanoic acid (CA), lauric acid (LA), myristic acid (MA), palmitic acid (PA) and stearic acid (SA) as raw materials and used as phase change materials. SiO_2 nanofibers and TiO_2-doped SiO_2 (TiO_2/SiO_2) nanofibers were prepared by calcination and used as supporting materials. Then the composite phase change materials were prepared by the method of physical adsorption of fatty acids on nanofibers. The morphology and properties of the composite phase change materials were studied. The PVP/Si O2 composite nanofibers were prepared. The thermal degradation process was studied by TGA. Then the Si O2 nanofibers were prepared by calcination at 500oC, 600oC and 700oC. The composition and functional groups of the nanofibers were characterized by FT-IR. The formation of Si O2 nanofibers at different calcination temperatures was compared and analyzed. The adsorption properties of nanofibers for methylene blue dye and CA-LA-PA ternary fatty acid hypoeutectic were studied. The results showed that the porous network Si O2 nanofibers prepared by calcination at 600oC had higher adsorption capacity. 2. The structure and morphology of Si O2 nanofibers were further characterized by XRD and SEM. The results showed that Si O2 nanofibers had good adsorption properties. The morphology, adsorption capacity, thermal storage and thermal energy storage/release properties of SiO2-based composite phase change materials were studied by means of SEM, adsorption properties, DSC and self-assembled thermal performance tester. The results showed that the binary fatty acid hypoeutectic was better. In the porous network structure of Si O2 nanofibers, the dispersion is attributed to the capillary effect and surface tension between fatty acids and Si O2. At the same time, the composite phase change materials have suitable phase transition temperature and higher enthalpy, and the electrospun Si O2 nanofibers improve the thermal energy storage/release rate of the composite phase change materials. TiO_2-doped SiO_2 (TiO_2/SiO_2) nanofibers were prepared by electrospinning and high temperature calcination with n-butyl titanate (TBT) and tetraethyl orthosilicate (TEOS) as precursors. The composition, crystal structure and morphology of TiO_2/SiO_2 nanofibers prepared at three calcination temperatures (600oC, 900oC and 1200oC) were characterized by FT-IR, XRD and SEM. The results show that the amorphous structure of TiO_2/SiO_2 nanofibers changes from 600oC to 1200oC with the increase of calcination temperature, and the morphology of the nanofibers changes from uniform and smooth cylinder at 600oC to calcification at 1200oC. In addition, the TiO_2/SiO_2-based composites are prepared by SEM, adsorption properties and DSC at different heat treatment temperatures. The morphology, adsorption capacity and thermal properties of the phase change materials were compared. The results showed that the low-eutectic binary fatty acids were dispersed uniformly in the porous network structure of TiO_2/SiO_2 nanofibers. With the increase of calcination temperature, the morphology of TiO_2/Si_2 nanofibers changed, resulting in low-eutectic binary fatty acids. The decrease of the adsorption capacity of the melt leads to the decrease of the thermal storage property of the composite shape stabilized phase change material.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34;TQ340.64
本文编号：2208470
[Abstract]:The rational use of energy and the development of new energy sources have always been the focus of attention. In order to alleviate the contradiction between energy shortage, rapid growth of energy consumption and environmental pollution, the use of latent heat of phase change materials for energy storage and release is a new environmental protection and energy-saving technology, which can be used to control the temperature of the system or environment. Fatty acids are a kind of important solid-liquid phase change materials, which have the advantages of high heat storage density and constant temperature during phase change process. However, they have the disadvantages of large phase change volume change and low thermal conductivity. However, electrospun inorganic nanofibers have high specific surface area and unique network junction. Structures, abundant porosity and high thermal conductivity can be used as support materials for solid-liquid phase change materials, which can effectively solve the leakage and low thermal conductivity problems in fatty acid phase change process. CA binary fatty acid eutectics (CA-LA, CA-MA, CA-PA and CA-SA) and CA-LA-PA ternary fatty acid eutectics were prepared by melt mixing and ultrasonic dispersion using decanoic acid (CA), lauric acid (LA), myristic acid (MA), palmitic acid (PA) and stearic acid (SA) as raw materials and used as phase change materials. SiO_2 nanofibers and TiO_2-doped SiO_2 (TiO_2/SiO_2) nanofibers were prepared by calcination and used as supporting materials. Then the composite phase change materials were prepared by the method of physical adsorption of fatty acids on nanofibers. The morphology and properties of the composite phase change materials were studied. The PVP/Si O2 composite nanofibers were prepared. The thermal degradation process was studied by TGA. Then the Si O2 nanofibers were prepared by calcination at 500oC, 600oC and 700oC. The composition and functional groups of the nanofibers were characterized by FT-IR. The formation of Si O2 nanofibers at different calcination temperatures was compared and analyzed. The adsorption properties of nanofibers for methylene blue dye and CA-LA-PA ternary fatty acid hypoeutectic were studied. The results showed that the porous network Si O2 nanofibers prepared by calcination at 600oC had higher adsorption capacity. 2. The structure and morphology of Si O2 nanofibers were further characterized by XRD and SEM. The results showed that Si O2 nanofibers had good adsorption properties. The morphology, adsorption capacity, thermal storage and thermal energy storage/release properties of SiO2-based composite phase change materials were studied by means of SEM, adsorption properties, DSC and self-assembled thermal performance tester. The results showed that the binary fatty acid hypoeutectic was better. In the porous network structure of Si O2 nanofibers, the dispersion is attributed to the capillary effect and surface tension between fatty acids and Si O2. At the same time, the composite phase change materials have suitable phase transition temperature and higher enthalpy, and the electrospun Si O2 nanofibers improve the thermal energy storage/release rate of the composite phase change materials. TiO_2-doped SiO_2 (TiO_2/SiO_2) nanofibers were prepared by electrospinning and high temperature calcination with n-butyl titanate (TBT) and tetraethyl orthosilicate (TEOS) as precursors. The composition, crystal structure and morphology of TiO_2/SiO_2 nanofibers prepared at three calcination temperatures (600oC, 900oC and 1200oC) were characterized by FT-IR, XRD and SEM. The results show that the amorphous structure of TiO_2/SiO_2 nanofibers changes from 600oC to 1200oC with the increase of calcination temperature, and the morphology of the nanofibers changes from uniform and smooth cylinder at 600oC to calcification at 1200oC. In addition, the TiO_2/SiO_2-based composites are prepared by SEM, adsorption properties and DSC at different heat treatment temperatures. The morphology, adsorption capacity and thermal properties of the phase change materials were compared. The results showed that the low-eutectic binary fatty acids were dispersed uniformly in the porous network structure of TiO_2/SiO_2 nanofibers. With the increase of calcination temperature, the morphology of TiO_2/Si_2 nanofibers changed, resulting in low-eutectic binary fatty acids. The decrease of the adsorption capacity of the melt leads to the decrease of the thermal storage property of the composite shape stabilized phase change material.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34;TQ340.64
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