【摘要】：微膠囊是指一種具有核殼結(jié)構(gòu),尺寸在幾十納米至幾百微米之間,具有半透性或密封性的球形或者其他形狀的微納米顆粒,具有控制釋放、增加物質(zhì)穩(wěn)定性和改變物質(zhì)體積、質(zhì)量和性質(zhì)等功能。目前所存在的微膠囊,往往只具有一種特殊性質(zhì),本實(shí)驗(yàn)希望通過對(duì)不同芯材和壁材的選取,在繼承芯材和壁材自身性質(zhì)的同時(shí),制備出具有自修復(fù)、自清潔、儲(chǔ)熱、導(dǎo)電、吸波、抗菌等其中兩種或多種性質(zhì)的微膠囊。本文選取相變溫度在28.18°C接近室溫的十八烷作為芯材物質(zhì),具有耐弱堿、耐弱酸、絕緣性優(yōu)良、耐磨性強(qiáng)、價(jià)格便宜的脲醛樹脂作為壁材。通過原位聚合法,制備了表面為多級(jí)微-納米結(jié)構(gòu),具有超疏水性、自清潔性能和儲(chǔ)熱釋熱性能的微膠囊。討論了在制備過程中,脲醛樹脂預(yù)聚物形成的溫度、pH值、摩爾比、PCM(Phase Change Material)乳液的溫度、表面活性劑的種類、表面活性劑的濃度、間苯二酚、攪拌速度和攪拌時(shí)間等對(duì)微膠囊的影響。確定制備微膠囊的最優(yōu)工藝為:形成脲醛樹脂預(yù)聚物的甲醛和尿素摩爾比為1.9:1;反應(yīng)溫度為70°C,pH值為8.00;表面活性劑使用濃度為6.6 g/L的EMA(聚乙烯馬來酸酐共聚物)水溶液,并添加4.2 g/L的間苯二酚(加速脲醛樹脂固化);在微膠囊的形成中,體系溫度維持35°C,分散液滴攪拌速率600~1000 r/min,時(shí)間為10 min,預(yù)聚物聚合轉(zhuǎn)速300~600 r/min時(shí)間0.5~1 h;脲醛樹脂固化溫度為55°C,時(shí)間為1 h。利用光學(xué)顯微鏡、掃描電子顯微鏡、X射線能譜儀、傅里葉變換紅外光譜儀、熱重分析儀、接觸角測(cè)量?jī)x、差示掃描量熱儀和熱成像儀等設(shè)備對(duì)微膠囊形貌結(jié)構(gòu)、熱穩(wěn)定性、熱性能、親疏水性、自清潔性能和儲(chǔ)熱釋熱性能進(jìn)行測(cè)試。結(jié)果表明,微膠囊為球形,且具有核殼結(jié)構(gòu),尺寸均值分別為80~200μm,壁厚150~400 nm;微膠囊表面粗糙,分布著200~500 nm納米級(jí)的脲醛樹脂顆粒,構(gòu)建成多級(jí)微-納米的結(jié)構(gòu);微膠囊表面的元素為C、H、O三種元素;微膠囊芯材十八烷和壁材脲醛樹脂之間沒有發(fā)生化學(xué)反應(yīng),并且相互之間得到了很好的交聯(lián),在微膠囊壁材中不含有游離的甲醛;十八烷的微膠囊化阻礙了十八烷的揮發(fā),將十八烷開始揮發(fā)的溫度由130°C提升到了210°C,提升了十八烷相變微膠囊的熱性能,經(jīng)過100次循環(huán),十八烷微膠囊的熱性能略有下降,結(jié)晶溫度和融化溫度等基本無(wú)變化;微膠囊具有超疏水性,疏水角大于160°,滾動(dòng)角小于12°,在長(zhǎng)期放置在空氣之后,疏水角仍大于160°,滾動(dòng)角仍小于12°,常溫常壓下具有良好的穩(wěn)定性;在自清潔的測(cè)試中,采用炭黑和沙土進(jìn)行測(cè)試,微膠囊具有良好的自清潔性能并且性能可以長(zhǎng)期維持;在儲(chǔ)熱釋放性能測(cè)試中,含有十八烷微膠囊的涂層可以在一定程度上消除溫度變化對(duì)涂層的影響,使溫度維持在28.2°C,具有良好的儲(chǔ)熱和釋熱性能。
[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 擄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 擄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 擄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 擄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 擄C to 210 擄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 擄and rolling angle less than 12 擄. After being placed in air for a long time, the hydrophobic angle is still more than 160 擄, the rolling angle is still less than 12 擄, 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 擄C. it has good heat storage and heat release properties.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB34

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