多功能微胶囊的制备及性能的研究

发布时间：2018-09-14 11:07

【摘要】：微胶囊是指一种具有核壳结构,尺寸在几十纳米至几百微米之间,具有半透性或密封性的球形或者其他形状的微纳米颗粒,具有控制释放、增加物质稳定性和改变物质体积、质量和性质等功能。目前所存在的微胶囊,往往只具有一种特殊性质,本实验希望通过对不同芯材和壁材的选取,在继承芯材和壁材自身性质的同时,制备出具有自修复、自清洁、储热、导电、吸波、抗菌等其中两种或多种性质的微胶囊。本文选取相变温度在28.18°C接近室温的十八烷作为芯材物质,具有耐弱碱、耐弱酸、绝缘性优良、耐磨性强、价格便宜的脲醛树脂作为壁材。通过原位聚合法,制备了表面为多级微-纳米结构,具有超疏水性、自清洁性能和储热释热性能的微胶囊。讨论了在制备过程中,脲醛树脂预聚物形成的温度、pH值、摩尔比、PCM(Phase Change Material)乳液的温度、表面活性剂的种类、表面活性剂的浓度、间苯二酚、搅拌速度和搅拌时间等对微胶囊的影响。确定制备微胶囊的最优工艺为:形成脲醛树脂预聚物的甲醛和尿素摩尔比为1.9:1;反应温度为70°C,pH值为8.00;表面活性剂使用浓度为6.6 g/L的EMA(聚乙烯马来酸酐共聚物)水溶液,并添加4.2 g/L的间苯二酚(加速脲醛树脂固化);在微胶囊的形成中,体系温度维持35°C,分散液滴搅拌速率600~1000 r/min,时间为10 min,预聚物聚合转速300~600 r/min时间0.5~1 h;脲醛树脂固化温度为55°C,时间为1 h。利用光学显微镜、扫描电子显微镜、X射线能谱仪、傅里叶变换红外光谱仪、热重分析仪、接触角测量仪、差示扫描量热仪和热成像仪等设备对微胶囊形貌结构、热稳定性、热性能、亲疏水性、自清洁性能和储热释热性能进行测试。结果表明,微胶囊为球形,且具有核壳结构,尺寸均值分别为80~200μm,壁厚150~400 nm;微胶囊表面粗糙,分布着200~500 nm纳米级的脲醛树脂颗粒,构建成多级微-纳米的结构;微胶囊表面的元素为C、H、O三种元素;微胶囊芯材十八烷和壁材脲醛树脂之间没有发生化学反应,并且相互之间得到了很好的交联,在微胶囊壁材中不含有游离的甲醛;十八烷的微胶囊化阻碍了十八烷的挥发,将十八烷开始挥发的温度由130°C提升到了210°C,提升了十八烷相变微胶囊的热性能,经过100次循环,十八烷微胶囊的热性能略有下降,结晶温度和融化温度等基本无变化;微胶囊具有超疏水性,疏水角大于160°,滚动角小于12°,在长期放置在空气之后,疏水角仍大于160°,滚动角仍小于12°,常温常压下具有良好的稳定性;在自清洁的测试中,采用炭黑和沙土进行测试,微胶囊具有良好的自清洁性能并且性能可以长期维持;在储热释放性能测试中,含有十八烷微胶囊的涂层可以在一定程度上消除温度变化对涂层的影响,使温度维持在28.2°C,具有良好的储热和释热性能。
[Abstract]:A microcapsule is a spherical or other shape microparticle with a core-shell structure, ranging in size from tens of nanometers to several hundred microns, with semi-permeable or hermetic properties, with controlled release, increased material stability, and changes in material volume. Functions such as quality and quality. At present, microcapsules usually have only one kind of special properties. This experiment hopes that by selecting different core and wall materials, we can obtain self-repairing, self-cleaning, heat storage, conductive, self-repairing, self-cleaning, heat storage and conducting, while inheriting the properties of core and wall materials. A microcapsule of two or more properties, such as absorbing, antimicrobial, etc. In this paper, octadecane with phase transition temperature of 28.18 掳C and close to room temperature is chosen as core material, with weak alkali resistance, weak acid resistance, excellent insulation, strong wear resistance and cheap UF resin as wall material. By in-situ polymerization, microcapsules with multistage microstructures, superhydrophobicity, self-cleaning and heat storage and heat release properties were prepared. The temperature and pH value of the prepolymer of urea-formaldehyde resin, the temperature of (Phase Change Material) emulsion, the type of surfactant, the concentration of surfactant and resorcinol were discussed. Effects of stirring speed and stirring time on microcapsules. The optimum conditions for the preparation of microcapsules were as follows: the molar ratio of formaldehyde to urea was 1.9: 1; the reaction temperature was 70 掳C ~ (-1); the pH value was 8.00; and the aqueous solution of polyvinyl maleic anhydride copolymer (EMA) with concentration of 6.6 g / L was used as surfactant. In addition, 4.2 g / L resorcinol (accelerated curing of urea-formaldehyde resin) was added in the formation of microcapsules, The reaction temperature was maintained at 35 掳C, the stirring rate of the dispersed droplet was 600ml / min, and the polymerization speed of 10 min, prepolymer was 300,600 r/min / min, and the curing temperature of urea-formaldehyde resin was 55 掳C and the time was 1 h. By means of optical microscope, scanning electron microscope, X-ray energy spectrometer, Fourier transform infrared spectrometer, thermogravimetric analyzer, contact angle measuring instrument, differential scanning calorimeter and thermal imager, the morphology and thermal stability of microcapsules were studied. Thermal properties, hydrophobicity, self-cleaning properties and heat storage and heat release properties were tested. The results showed that the microcapsules were spherical and had core-shell structure. The average size of microcapsules was 80 渭 m. The surface of the microcapsules was rough with a wall thickness of 150,400 nm;. There were 200 nm nanocrystalline urea-formaldehyde resin particles distributed in the microcapsules to form a multi-stage micro-nano structure. There was no chemical reaction between octadecane and urea-formaldehyde resin in the microcapsule core and there was no free formaldehyde in the microcapsule wall. The octadecane microencapsulation hinders the volatilization of octadecane. The temperature at which octadecane begins to volatilize is raised from 130 掳C to 210 掳C, which enhances the thermal properties of octadecane phase change microcapsules. After 100 cycles, the thermal properties of octadecane microcapsules decrease slightly. The microcapsules have super hydrophobicity, hydrophobic angle more than 160 掳and rolling angle less than 12 掳. After being placed in air for a long time, the hydrophobic angle is still more than 160 掳, the rolling angle is still less than 12 掳, and the microcapsule has good stability at room temperature and atmospheric pressure. In the self-cleaning test, the microcapsules have good self-cleaning performance and can be maintained for a long time by using carbon black and sand. The coating containing octadecane microcapsule can eliminate the influence of temperature change on the coating to a certain extent and keep the temperature at 28.2 掳C. it has good heat storage and heat release properties.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB34

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