【作者】 余飞；

【导师】 曾幸荣；

【作者基本信息】 华南理工大学 ， 材料学， 2009， 博士

【摘要】 随着全球工业的高速发展,全球能源日益短缺。利用相变材料相变过程中的相变潜热来实现能量的储存和利用,有助于提高能效和开发可再生能源,但是相变材料本身存在相变过程中流动、相容性差和腐蚀性等问题。采用微/纳米胶囊化技术,制备新型相变储热复合材料,是解决上述问题的有效手段。本论文通过原位聚合法,将具有较高相变潜热、较合适相变温度的相变材料正十二醇封装在三聚氰胺-甲醛树脂内,制备了相变储热微胶囊,并用多种改性剂对其进行改性;通过细乳液聚合法,制备了以正十二醇为芯材、以聚甲基丙烯酸甲酯(PMMA)为壁材的相变储热纳米胶囊;将正十二醇相变储热微胶囊和纳米胶囊分别加入到普通石膏板和水性涂料中,制备了具有相变储热功能的复合石膏板和水性复合涂料。研究了正十二醇相变储热微胶囊和纳米胶囊的结构与性能,测试了相变储热石膏板和相变储热水性涂料的储放热特性,对其在节能领域的应用进行了探索,为其实际应用提供了技术依据。论文的研究内容和成果包括如下四点。第一:以相变材料正十二醇为包封对象,以三聚氰胺和甲醛为单体,通过原位聚合法,制备了以三聚氰胺-甲醛树脂为壁材、以正十二醇为芯材、具有较高相变潜热、较合适相变温度、结构致密的相变储热微胶囊,应用差示扫描量热仪(DSC)、热重分析仪(TG)、扫描电子显微镜(SEM)、傅立叶红外光谱仪(FTIR)和激光散射粒度分析仪等手段,研究了乳化剂种类、乳化剂用量、相变材料极性、乳化搅拌速度以及芯材投料质量分数等对微胶囊储热性能、包封效率以及微胶囊形貌的影响,并对正十二醇相变储热微胶囊的形成机理进行了探讨。发现乳化剂的乳化分散作用和电荷效应对微胶囊的形成起到重要作用,阴离子型苯乙烯-马来酸酐共聚物(SMA)乳化剂SMA1000HNa有助于三聚氰胺-甲醛树脂对正十二醇的包封。正十二醇相变储热微胶囊最佳的制备条件是乳化搅拌速度为4500 r/min,乳化剂相对相变材料质量分数为4.8%,芯材投料质量分数为81%,所制备的微胶囊相变潜热达最高值187.5J/g,相变材料包封效率为93.1%,相变温度为21.5℃,平均粒径为30.6μm,多分散指数为1.190。第二:分别以亲水型纳米SiO2、氯化钠以及聚乙烯醇(PVA)等三种物质作为改性剂,对三聚氰胺-甲醛树脂进行改性,通过原位聚合法,制备了以改性三聚氰胺-甲醛树脂为壁材、正十二醇为芯材的改性相变储热微胶囊,探讨了改性剂类型和改性剂用量对微胶囊储热性能、破损率及表面形貌的影响,用DSC、SEM和FTIR等手段对其进行了表征。发现随着改性剂用量的增加,微胶囊的相变潜热都是先增加后降低的,破损率都是先降低后增加的。PVA的改性效果最佳,改性相变储热微胶囊的综合性能最好,当其用量为2%时,微胶囊相变潜热提高了16.9%,破损率降低了68.6%。第三,以相变材料正十二醇为包封对象,以甲基丙烯酸甲酯(MMA)为主单体,应用可聚合型乳化剂DNS-86,以正十六烷(HD)为助乳化剂,通过细乳液聚合法,制备了以PMMA为壁材、以正十二醇为芯材、具有较高相变潜热、较合适相变温度、形态规整度高的相变储热纳米胶囊,采用DSC、TG、FTIR、透射电子显微镜(TEM)以及激光粒度分析仪等手段,研究了乳化剂、助乳化剂、引发剂、共聚单体以及芯材投料质量分数等对纳米胶囊结构与性能的影响,探讨了正十二醇相变储热纳米胶囊的形成机理。发现助乳化剂HD的使用,并采取加入水相液的方式,有助于PMMA对相变材料正十二醇的包封。PMMA-正十二醇纳米胶囊最佳的制备条件是乳化剂DNS-86用量(相对油相液质量分数)为3%,助乳化剂正十六烷用量(相对油相液质量分数)为2%,油溶性引发剂偶氮二异丁腈(AIBN)用量(相对单体质量分数)为2%,芯材正十二醇投料质量分数为48%,制备的纳米胶囊相变潜热及相变材料包封效率分别为98.8J/g和82.2%,相变温度为18.2℃,粒径主要分布在50nm到100nm的范围内。亲水共聚单体丙烯酰胺(AM)和丙烯酸(AA)的加入,有助于对相变材料正十二醇的包封。当AM用量(相对单体总质量)为4%时,胶囊相变潜热及相变材料包封效率增加至最高值,分别为109.3J/g和91.6%。第四,将正十二醇相变储热微胶囊和纳米胶囊分别加入普通石膏板和水性丙烯酸酯涂料中,制备了具有储热功能的复合石膏板和水性丙烯酸酯复合涂料,研究了储热胶囊对其储热性能、调温性能、隔热性能等的影响,用石膏板建立了建筑物房间模型,模拟在碘钨灯照射下模型内部温度的变化情况,测试了相变储热石膏板和相变储热水性丙烯酸酯涂料在模型上的应用效果。发现相变储热石膏板和相变储热水性丙烯酸酯涂料的相变潜热和储热效果随相变储热胶囊含量增加而增加。当相变储热石膏板中微胶囊含量为30wt%时,其相变潜热为45.6J/g,从10℃升温到48℃所需时间增加了130%,从48℃降温到10℃所需时间增加了120%,其建筑物模型内部温度比普通石膏板模型低4℃。当相变储热水性丙烯酸酯涂料中纳米胶囊含量为50wt%时,其相变潜热为54.3J/g,涂层温度比不含储热胶囊的涂层低2.5℃,相变储热涂层石膏板模型内部温度比普通石膏板模型低2.5℃。更多还原

【Abstract】 With the rapid development of global industry, the energy sources in the world are missing day by day. Phase change materials (PCM) can be used for energy storage and utilization through the phase change latent heat during their phase change process, which is helpful to improve energy efficiency and develop new renewable energy. However, PCM have many disadvantages, such as flowing during the phase change process, bad compatibility and corrosion. Microcapsule or nanocapsule technology can be used to fabricate new phase change thermal storage composite materials, which is an effective method to solve those problems. In this work, n-dodecanol with high phase change latent heat and suitable phase change temperature was encapsulated as core by in-situ polymerization with melamine-formaldehyde (MF) resin as shell, and the microcapsules containing phase change material (microPCMs) synthesized were modified by different kinds of modifiers. The phase change thermal storage nanocapsules with n-dodecanol as core and polymethyl methacrylate (PMMA) as shell were prepared through miniemulsion polymerization. Phase change thermal storage composite gypsum board and waterborne composite coating were prepared by incorporating phase change thermal storage microcapsules and nanocapsules containing n-dodecanol into ordinary gypsum board and waterborne coating. The structure and properties of phase change thermal storage microcapsules and nanocapsules containing n-dodecanol were studied. The thermal energy absorbing and releasing performances of phase change thermal storage composite gypsum board and waterborne composite coating were studied and their applications in the fields of energy saving were explored, which provide technical basis for the practical application. The main research contents and achievements are listed as following:Firstly, n-dodecanol was used to be encapsulated by in-situ polymerization with monomers of melamine and formaldehyde, and microPCMs with high phase change latent heat, suitable phase change temperature and compact structure were prepared with MF resin as shell and n-dodecanol as core. The influence of emulsifier type, emulsifier amount, PCM polarity, emulsification stirring speed and feeding mass fraction of n-dodecanol on the thermal storage properties, encapsulation efficiency and morphology of microPCMs were studied by using DSC, TG, SEM, FTIR, and laser particle diameter analyzer and the formation mechanism of microPCMs were discussed. It’s found that the dispersion and charge effect of emulsifiers have great influence on the formation of MicroPCMs and anionic styrene-maleic anhydride copolymer (SMA) emulsifier is helpful for the encapsulation of n-dodecanol with MF resin. The optimal preparation condition of MicroPCMs containing n-dodecanol is that emulsification stirring speed is 4500 r/min, mass ratio of emulsifier to n-dodecanol is 4.8%, and the feeding mass fraction of n-dodecanol is 81%. MicroPCMs with the maximum phase change latent heat of 187.5J/g, encapsulation efficiency of 93.1%, phase change temperature of 21.5℃, mean diameter of 30.6μm and polydispersity index of 1.190 are obtained.Secondly, three kinds of modifiers hydrophilic nano-SiO2, sodium chloride (NaCl) and polyvinyl alcohol (PVA) were used to modify MF resin, respectively, and modified microPCMs were prepared by in-situ polymerization with modified MF resin as shell and n-dodecanol as core. The influence of modifier type and modifier amount on the thermal storage properties, cracking ratios and morphology of modified microPCMs were studied by using DSC, SEM and FTIR. It’s found that the phase change latents of modified microcapsules increase firstly and decrease subsequently with the increasing of the amount of modifier, while the cracking ratios decrease firstly and increase subsequently. PVA is the best modifier, by which microPCMs modified possess the optimal comprehensive performances. When the mass ratio of PVA to shell material is 2%, the phase change latent heat of modified microPCM increases by 16.9% and the cracking ratio deceases by 68.6%.Thirdly, n-dodecanol was used to be encapsulated by miniemulsion polymerization with main monomers of MMA, co-emulsifier of n-hexadecane (HD) and polymerisable emulsifier of DNS-86, and uniform phase change thermal storage nanocapsules with high phase change latent heat and suitable phase change temperature were prepared with PMMA as shell and n-dodecanol as core. The influence of emulsifier, co-emulsifier, initiator, co-monomer and feeding mass fraction of n-dodecanol on the structure and properties of nanocapsules were studied by using DSC, TG, TEM, FTIR, and laser particle diameter analyzer and the formation mechanism of nanocapsules were discussed. It’s found that application of co-emulsifier n-hexadecane with the way of adding into water phase is helpful for the encapsulation of n-dodecanol with PMMA. The optimal preparation condition of PMMA nanocapsules containing n-dodecanol is that the mass ratio of polymerisable anion emulsifier DNS-86 to oil phase is 3%, the mass ratio of co-emulsifier n-hexadecane to oil phase is 2%, the mass ratio of oil-soluble initiator azobisisobutyronitrile (AIBN) to total monomer is 2%, and the feeding mass fraction of n-dodecanol is 48%. Under the condition, nanocapsules with the phase change latent heat of 98.8J/g, phase change temperature of 18.2℃, encapsulation efficiency of 82.2% and main diameter range of 50-100nm are obtained. Hydrophilic co-monomer acrylamine (AM) and acrylic acid (AA) is helpful for encapsulation of PCM n-dodecanol. When mass ratio of AM to total monomer is 4%, the phase change latent heat of nanocapsule and encapsulation efficiency of n-dodecanol reach to the highest value of 109.3J/g and 91.6%, respectively.Finally, composite gypsum board and waterborne acrylate composite coating with the function of phase change thermal storage were prepared by incorporating microcapsules and nanocapsules containing n-dodecanol into ordinary gypsum board and waterborne acrylate coating, respectively. The influence of phase change thermal storage microcapsules and nanocapsules on the thermal storage properties, temperature adjusting performance, and heat-insulating ability of composite gypsum board and waterborne acrylate composite coating were studied. Architecture model was made with gypsum boards to stimulate the variation of indoor temperature of the model under the light of iodine tungsten lamp and test the application effect of phase change thermal storage gypsum board and waterborne acrylate coating. With the increasing of the contents of phase change thermal storage microcapsules and nanocapsules, the phase change latent heat and thermal storage effect of phase change thermal storage gypsum board and phase change thermal storage waterborne acrylate coating increase. When the mass content of microcapsules in gypsum board is 30%, the phase change latent heat of composite gypsum board is 45.6J/g, the time of temperature increasing from 10℃to 48℃increases by 130% and the time of temperature decreasing from 48℃to 10℃increases by 120%, and the indoor temperature of model with composite gypsum board is 4℃lower than that of model with ordinary gypsum board. When the mass content of nanocapsules in waterborne acrylate coating is 50%, the phase change latent heat of waterborne acrylate composite coating is 54.3J/g, the temperature of composite acrylate coating is 2.5℃lower than that of coating without thermal storage nanocapsules, and the indoor temperature of model with waterborne acrylate composite coating-gypsum board is 2.5℃lower than that of model with ordinary gypsum board.更多还原