【作者】 丘晓琳；

【导师】 唐国翌；

【作者基本信息】 清华大学 ， 材料科学与工程， 2013， 博士

【摘要】 相变储能材料（PCMs）可在恒定温度下提供高能量密度，在能源问题日益凸显的今天备受关注。相变储能微胶囊（MicroPCMs）既可解决PCMs的泄露及体积变化问题，又可提高PCMs的稳定性、耐久性及基体相容性。丙烯酸树脂具有化学稳定性高、安全无害、价格合理等优点。本论文选用不同特性的丙烯酸酯类或甲基丙烯酸酯类单体合成不同类型的丙烯酸树脂作为囊材，采用悬浮聚合法制备出一系列包覆正烷烃类PCMs的MicroPCMs，并对其性能进行了研究；同时，通过交联、共聚等方式对囊材改性以提高MicroPCMs的机械强度、储热性能及耐热性能。对聚甲基丙烯酸甲酯（PMMA）进行交联改性以提高囊材的强度和刚度，并系统研究了交联剂类型对MicroPCMs性能的影响。增加交联剂官能度或引入刚性苯环，可改善MicroPCMs的力学性能、储热性能及耐热性能。季戊四醇四丙烯酸酯（PETRA）交联MicroPCMs具有最高熔融焓(156.4J/g)和结晶焓(182.6J/g)，其耐热温度达239oC；以其小试工艺为蓝本扩大至10L中试生产，为产业化奠定了基础。引入长链烷基丙烯酸酯类单体与MMA共聚以改进囊材柔韧性、储热能力与耐热性能，并从分子结构层面系统分析了单体性质与MicroPCMs性能的相关性。引入甲基丙烯酸正丁酯（BMA）的MicroPCMs储热能力略高于PMMA基MicroPCMs；MicroPCMs的储热能力随着第二单体烷基链的增长而降低。引入甲基丙烯酸十八烷基酯（SMA）的MicroPCMs耐热稳定性优良，其耐热温度达255oC。制备出一系列长链烷基丙烯酸酯均聚物基MicroPCMs以探讨不同类型丙烯酸树脂作为囊材的优劣势。丙烯酸正丁酯（BA）或BMA合成的MicroPCMs，其储热性能明显优于甲基丙烯酸月桂酯（LMA）或SMA合成的MicroPCMs；二乙烯基苯（DVB）交联的PBMA基MicroPCMs的耐热温度最高，达248oC。1000次冷热循环后，MicroPCMs相变焓值的降幅约10%，显示出良好的耐冷热循环能力。引入极性较高的单体与BMA共聚以提高成囊驱动力。引入甲基丙烯酸（MAA）或丙烯酸（AA）后，MicroPCMs储热能力和耐热能力明显改善。未复合与复合MicroPCMs的石膏板加热时温度随时间变化对比表明，复合MicroPCMs的石膏板具良好的调温性能。更多还原

【Abstract】 Phase change materials (PCMs) is promising for use in thermal energy storage andthermal regulation due to their characteristic of storing thermal energy at a constanttemperature via phase transition and their ability to provide high energy storagedensities. Microencapsulated phase change materials (MicroPCMs) are PCMs inliquid/solid form enveloped within a polymer or inorganic shell, the size of which is inthe range of1-1000μm. There are many advantages of MicroPCMs, such as preventingthe interior PCMs from leakage, withstanding the change in the storage material volumeduring phase transition, reducing reactivity of PCMs toward the outside environmentand increasing heat transfer area. Acrylic resins are very attractive shell materialsbecause of their good impact strength, excellent dimensional stability, weatherresistance, non-toxic, ease of fabrication and commercial availability at reasonable cost.In this paper, microcapsules containing n-alkane with different acrylic-based polymershells were fabricated by a suspension-like polymerization. The as-preparedMicroPCMs were characterized and analyzed.Firstly, MicroPCMs with the crosslinked methylmethacrylate (MMA)-basedpolymer as shells were prepared.1,4-butylene glycol diacrylate (BDDA),divinylbenzene (DVB), trimethylolpropanetriacrylate (TMPTA) and pentaerythritoltetraacrylate (PETRA) were employed as crosslinking agents. Increasing crosslinkablefunctional moieties of the crosslinking agents and amount of crosslinking agent led toan increase in the shell mechanical strength, the heat storage capacities and the thermalstabilities of the MicroPCMs. Both shell mechanical strength and heat capacity ofMicroPCMs with DVB were higher than those of MicroPCMs prepared with BDDAdue to the two-vinyl group in DVB connecting with rigid phenyl group. Pilot-scalechemical reaction was carried out based on the above synthetic process, and a yield ofmore than1kg can be obtained per time.Secondly, MicroPCMs with different methylmethacrylate (MMA)-basedcopolymer shells were fabricated. Butyl acrylate (BA), butyl methacrylate (BMA),lauryl methacrylate (LMA) and stearyl methacrylate (SMA) were employed asmonomers to copolymerize with MMA. Heat capacities of MicroPCMs decreased withthe increase in the length of the side chains of the monomer, which is BMA<LMA<SMA. Thermal resistant temperatures of both uncrosslinked andcrosslinked MicroPCMs had the same sequence of changes, i.e., MicroPCMs withP(MMA-co-SMA)> MicroPCMs with P(MMA-co-BMA)> MicroPCMs withP(MMA-co-BA)> MicroPCMs with P(MMA-co-LMA).Thirdly, MicroPCMs with crosslinked PBMA, PBA, PLMA and PSMA shellswere fabricated. DVB and pentaerythritol triacrylate (PETA) were employed ascrosslinking agents. The MicroPCMs prepared by using DVB show greater heatcapacities and thermal stabilities compared with the MicroPCMs prepared by usingPETA. Heat capacities of both the MicroPCMs with PBMA and PBA were higher thanthose of MicroPCMs with PLMA and PSMA. The MicroPCMs with PBMA has thehighest thermal resistant temperature when prepared by DVB, while the MicroPCMswith PSMA exhibits the greatest thermal stability when prepared by PETA.Finally, MicroPCMs with different BMA-based copolymer shells were synthesized.Methacrylic acid (MAA) and acrylic acid (AA) were employed as monomers tocopolymerize with BMA. The performances of MicroPCMs have been improved whenMAA or AA was introduced to the polymer shells. Furthermore, heat capacity andthermal stability enhanced with the increasing of MAA content in the acryliccomposition of the shell. Thermal images showed that the gypsum board withincorporated P(BMA-co-MAA)/n-octadecane microcapsules possessedtemperature-regulated property.更多还原