【作者】 陈嘉巍；

【导师】 方玉堂；

【作者基本信息】 华南理工大学 ， 化学工程， 2012， 硕士

【摘要】 随着全球经济和工业的迅速发展，能源短缺日益凸显。相变储能技术利用相变潜热来实现能量的储存和利用，有助于提高能源利用效率，节约能源。胶囊化技术将相变材料固定在微-纳米容器中能够改善相变材料本身存在的相变过程流动性、相容性差及腐蚀性等不足。本文采用超声波乳化、细乳液原位聚合工艺，以苯乙烯聚合物为壳体，工业级石蜡RT42为芯材，制备出RT42/聚苯乙烯纳米胶囊相变乳液。系统考察超声参数、聚合反应条件、引发剂、分散剂、乳化剂、亲水性共聚单体、核/苯乙烯单体比等因素对聚合反应影响。采用纳米激光粒度仪、透射电子显微镜（TEM）、傅里叶红外光谱（FTIR）、差示扫描量热（DSC）、热失重（TG）、热常数分析仪、旋转粘度计及高低温实验等分析手段对纳米胶囊及其乳液形貌、组成及热物性等进行表征。研究表明，采用油溶性引发剂偶氮二异丁腈（AIBN）制备的纳米胶囊相变潜热明显高于水溶性引发剂过硫酸钾（KPS）的；分散剂聚乙烯吡咯烷酮（PVP）能够改善RT42的分散性和乳液稳定性；可聚合型乳化剂（DNS-86）与传统乳化剂【（十二烷基硫酸钠（SDS）和辛烷基酚聚氧乙烯醚-10（OP-10）】复合有助于形成大小均一、性能稳定的纳米胶囊乳液；亲水性共聚单体加入可以改善胶囊囊壁性能，提高胶囊稳定性；核/苯乙烯单体质量比影响纳米胶囊的稳定性能和热性能。适宜的RT42/聚合物纳米相变胶囊乳液制备条件为：超声波功率调整值55%，超声时间15min，聚合时间6h，聚合温度60℃。PVP为0.4%（油相质量比，下同）；复合乳化剂（DNS-86:SDS:OP-10=2:1:1）总量为9%；AIBN0.4%；亲水性共聚单体丙烯酸乙酯EA3%；RT42与苯乙烯质量比为3:5。制备的纳米胶囊平均粒径为80.8nm，相变潜热达60.14kJ/kg，RT42包封率达92.9%，纳米胶囊粉末的比热容峰值达10.99kJ/kg·℃。制备的乳液比热容峰值5.29kJ/kg·℃，导热系数0.83W/m·K（42℃时），粘度低（质量分数20%乳液40℃为8.35cP）。此外，多次高低温循环后乳液的储热能力没有明显下降。表明合成的纳米胶囊相变乳液适宜作为潜热型功能热流体。更多还原

【Abstract】 With the rapid development of global economy and industry, the energy shortage hasbecome increasingly prominent. The technology of phase change energy storage, taking useof the latent heat during phase change process to realize thermal energy storage andutilization, is helpful to improve the efficiency of energy utilization and save energy.However, there are some disadvantages for phase change materials themselves, such as thefluidity during phase change process, the corrosivity and the poor compatibility.Encapsulation technology which fixes phase change materials into micrometer or nanonmetercontainers is expected to solve the above shortcomings.In this paper, the nanoencapsulated phase change materials (NEPCMs) with paraffinwax of RT42as core and polystyrene as shell were synthesized by ultrasonic technique andminiemulsion in-situ polymerization. The influences of ultrasonic parameters and reactionconditions, initiator, dispersant, surfactants, co-monomers, and the mass ratio of RT42andstyrene on polymerization were systematically investigated. The morphology, compositonand the thermo-physical properties of synthesized nanoencapsulated phase change materialsand latex were characterized by particle size analyzer, transmission electron microscope(TEM), fourier transform infrared spectroscopy (FTIR), differential scanningcalorimeter(DSC), thermogravimetric analyzer (TG), rotational viscometer and high-lowtemperature cycle test.The experimental results showed that, the latent heat of NEPCMs with2,2-azobisisobutyronitrile (AIBN) as initiator was obviously higher than that with potassiumpersulfate (KPS). The stability of emulsion and the dispersion of RT42were enhanced usingpolyvinylpyrrolidone (PVP) as dispersant. The combination of polymerizable emulsifier andtraditional emulsifier (sodium dodecylsulfate (SDS) and poly-(ethyleneglycol) monooctyl-phenyl ether (OP-10)) help to improve the stability of emulsion and produce uniformly sizedNEPCMs. Adding hydrophilic co-monomer was usful to improve the shell performance andform core-shell structure. The mass ratio of RT42and St determined the thermo-physicalperformance and the stability of NEPCMs.The optimal polymeriztion conditions of NEPCMs were that:55%power adjusted value, 15min ultrasonic time,6h reaction time,60℃reaction temperature,0.4%polyvinylpyrrolido-ne (PVP, mass fraction of the oil phase liquid, the same as follows),9%composite emulsifierwhich constituted by polymerizable emulsifier DNS-86, sodium dodecyl sulfate (SDS) andpoly-(ethylene glycol) monooctylphenyl ether(OP-10) with2:1:1mass ratio,0.4%AIBN,3%EA and3:5mass ratio of RT42and St. The average particle size of prepared nanocapsuleswas80.8nm and the phase change enthalpy was60.14kJ/kg. During the melting process,the peak of the specific heat capacity of powder sample reahed10.99kJ/kg·℃,and theencapsulation rate of RT42was92.9%. The tesed results of the synthesized latex showed that,the viscosity was only8.35cP at20%mass fration and40℃, and the thermal conductivitycoefficient and the specific capacity was0.83W/m·K and5.29kJ/kg·℃at42℃, respectively.In addition, after many times for high-low termperature thermal cycling experiment, the heatstorage capacity of emulsion was not significantly decreased. It suggests that the synthesizedNEPCMs emulsion was a potential candidate as latent functionally thermal fluid.更多还原