丙烯酸树脂-正十二烷醇相变微胶囊制备及性能表征
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摘要
微胶囊化相变材料具有储能密度高、相变温度近似恒定、便于储存和输运等特点,在热能储存、输运和利用领域具有广泛的应用前景。本工作采用悬浮聚合法辅以超声辐照手段合成了以正十二烷醇为芯材、丙烯酸树脂为壳材的新型高相变潜热相变微胶囊(MEPCM)颗粒。用扫描电子显微镜(SEM)、傅里叶红外光谱仪(FT-IR)、差式扫描量热仪(DSC)、热重分析仪(TGA)和激光粒度仪(LPSA)等设备对微胶囊性能进行了表征。结果表明,所制相变微胶囊呈较规则球体,粒径为638.14～1478.65 nm,中位径d50为933.91 nm。冷却过程中微胶囊芯呈两种不同的结晶过程,囊芯含量为43%,与设计值50%较接近,包覆率达86%,熔化相变潜热为93.31 kJ/kg;包覆后的相变材料融化温度为22.26℃,过冷度从4.61℃降至2.13℃。壳材不与芯材反应。MEPCM质量降低起始温度略高于纯正十二烷醇,封装可改善相变材料的热稳定性,该相变微胶囊具有良好的潜热储存能力和较快的温度变化响应速度。
With the characteristics of high energy storage density, approximate constant temperature of phase change and convenient to storage or transport, the microencapsulated phase change materials(MEPCM) have wide application prospect in the fields of energy storage, transport and utilization. However, the traditional MEPCM particles use formaldehyde as the shell material, which would release harmful substances during application process. Therefore, it is necessary to develop a new type of formaldehyde-free MEPCM. A novel MEPCM particles with n-dodecanol as core material and acrylic resin copolymers as shellmaterial using suspension polymerization under ultrasound irradiation condition were prepared in this work. The scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC), thermo-gravimetric analyzer(TGA) and laser particle size analyzer(LPSA) were employed to characterize the performance of MEPCM particles. The results indicated that the MCPM particles were almost regular and had a uniform particle size. The particle sizes of MEPCM were 638.14～1 478.65 nm, and the median diameter d50 was 933.91 nm which reaches nanometer scale. Two types of crystals were formed in core materials of all MEPCM particle during crystallization. The melting latent heat and the encapsulation efficiency of MEPCM reached to the maximum value of 93.31 kJ/kg and 86%, respectively. The melting temperature of MEPCM was 22.26℃, and the degree of supercooling reduced from 4.61 ℃ to 2.13℃. The proportion of core was 43%, it was closed to the design value of 50%. The shell material did not react with the core material. The mass reduce starting temperature of MEPCM was slightly higher than that of pure n-dodecanol, indicating that the thermal stability of the phase change material can be improved after encapsulation. In summary, the MEPCM had a good potential for energy storage and high response speed when face to temperature fluctuation.
With the characteristics of high energy storage density, approximate constant temperature of phase change and convenient to storage or transport, the microencapsulated phase change materials(MEPCM) have wide application prospect in the fields of energy storage, transport and utilization. However, the traditional MEPCM particles use formaldehyde as the shell material, which would release harmful substances during application process. Therefore, it is necessary to develop a new type of formaldehyde-free MEPCM. A novel MEPCM particles with n-dodecanol as core material and acrylic resin copolymers as shellmaterial using suspension polymerization under ultrasound irradiation condition were prepared in this work. The scanning electron microscope(SEM), Fourier transform infrared spectroscopy(FT-IR), differential scanning calorimetry(DSC), thermo-gravimetric analyzer(TGA) and laser particle size analyzer(LPSA) were employed to characterize the performance of MEPCM particles. The results indicated that the MCPM particles were almost regular and had a uniform particle size. The particle sizes of MEPCM were 638.14～1 478.65 nm, and the median diameter d50 was 933.91 nm which reaches nanometer scale. Two types of crystals were formed in core materials of all MEPCM particle during crystallization. The melting latent heat and the encapsulation efficiency of MEPCM reached to the maximum value of 93.31 kJ/kg and 86%, respectively. The melting temperature of MEPCM was 22.26℃, and the degree of supercooling reduced from 4.61 ℃ to 2.13℃. The proportion of core was 43%, it was closed to the design value of 50%. The shell material did not react with the core material. The mass reduce starting temperature of MEPCM was slightly higher than that of pure n-dodecanol, indicating that the thermal stability of the phase change material can be improved after encapsulation. In summary, the MEPCM had a good potential for energy storage and high response speed when face to temperature fluctuation.
引文
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[2]鲁进利,张汪林,韩亚芳,等.细小圆管内Micro-PCMS紊流对流传热特性的CFD-DPM模拟[J].过程工程学报,2015,15(5):758-763.Lu J L,Zhang W L,Han Y F,et al.CFD-DPM simulation on characteristics of turbulent flow and heat transfer for micro-PCMSin mini-pipe[J].The Chinese Journal of Process Engineering,2015,15(5):758-763.
[3]吴炳洋,郑帼,孙玉,等.石墨烯/正十八烷微胶囊的制备与及其热性能研究[J].高分子学报,2016,(2):242-249.Wu B Y,Zheng G,Sun Y,et al.Preparation and thermal performance of microcapsules with graphene/n-octadecane as core material[J].Acta Polymerica Sinica,2016,(2):242-249.
[4]Cui H Z,Feng T J,Yang H B,et al.Experimental study of carbon fiber reinforced alkali-activated slag composites with microencapsulated PCM for energy storage[J].Construction&Building Materials,2018,161:442-451.
[5]鲁进利,吕勇军,韩亚芳,等.细小槽道换热器内相变微胶囊悬浮液对流传热DPM模拟[J].过程工程学报,2018,18(5):951-956.Lu J L,LüY J,Han Y F,et al.Simulation on convective heat transfer of MPCMS in minichannel heat exchanger based on DPM model[J].The Chinese Journal of Process Engineering,2018,18(5):951-956.
[6]Alva G,Lin Y X,Liu L K,et al.Synthesis,characterization and applications of microencapsulated phase change materials in thermal energy storage:a review[J].Energy and Buildings,2017,144:276-294.
[7]Wang K,Shi L,Zhang J Y,et al.Preparation of paraffin@melamineformaldehyde resin microcapsules coated with silver nano-particles[C]//2013 International Conference on Materials for Renewable Energy and Environment.Chengdu:IEEE,2014:508-512.
[8]Fei X N,Zhao H B,Zhang B L,et al.Microencapsulation mechanism and size control of fragrance microcapsules with melamine resin shell[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2015,469:300-306.
[9]Chai Y Q,Zhao T B,Gao X,et al.Low cracking ratio of paraffin microcapsules shelled by hydroxyl terminated polydimethylsiloxane modified melamine-formaldehyde resin[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2018,538:86-93.
[10]Zhang X X,Fan Y F,Tao X M,et al.Fabrication and properties of microcapsules and nanocapsules containing n-octadecane[J].Materials Chemistry and Physics,2004,88(2/3):300-307.
[11]Li W,Wang J P,Wang X C,et al.Effects of ammonium chloride and heat treatment on residual formaldehyde contents of melamine-formaldehyde microcapsules[J].Colloid and Polymer Science,2007,285(15):1691-1697.
[12]Chang C C,Tsai Y L,Chiu J J,et al.Preparation of phase change materials microcapsules by using PMMA network-silica hybrid shell via sol-gel process[J].Journal of Applied Polymer Science,2009,112(3):1850-1857.
[13]Abhat A.Low temperature latent heat thermal energy storage:heat storage materials[J].Solar Energy,1983,30(4):313-332.
[14]Liu C Z,Rao Z H,Li Y M.Composites enhance heat transfer in paraffin/melamine resin microencapsulated phase change materials[J].Energy Technology,2016,4(4):496-501.
[15]Zhang L,Yang W B,Jiang Z N,et al.Graphene oxide-modified microencapsulated phase change materials with high encapsulation capacity and enhanced leakage-prevention performance[J].Applied Energy,2017,197:354-363.
[16]丘晓琳,唐国翌,宋国林,等.正十八烷/丙烯酸树脂相变微囊的制备与性能[J].现代化工,2016,36(8):92-95.Qiu X L,Tang G Y,Song G L,et al.Preparation and properties of microencapsulated n-octadecane with acrylic-based polymer as phase change materials[J].Modern Chemical Industry,2016,36(8):92-95.
[17]Suslick K S.Sonochemistry[J].Science,1990,247(4949):1439-1445.
[18]Suslick K S,Choe S B,Cichowlas A A,et al.Sonochemical synthesis of amorphous iron[J].Nature,1991,353(6343):414-416.
[19]Zhang X X,Fan Y F,Tao X M,et al.Crystallization and prevention of supercooling of microencapsulated n-alkanes[J].Journal of Colloid and Interface Science,2005,281(2):299-306.
[20]Su J F,Wang S B,Zhou J W,et al.Fabrication and interfacial morphologies of methanol-melamine-formaldehyde(MMF)shell microPCMs/epoxy composites[J].Colloid and Polymer Science,2011,289(2):169-177.
[21]Chen Z H,Yu F,Zeng X R,et al.Preparation,characterization and thermal properties of nanocapsules containing phase change material n-dodecanol by miniemulsion polymerization with polymerizable emulsifier[J].Applied Energy,2012,91(1):7-12.
[22]张浩.基于光催化性能的Cu-Ce/TiO2湿性能[J].材料工程,2018,46(1):114-118.Zhang H.Cu-Ce/TiO2 moisture performance based on photocatalytic performance[J].Journal of Materials Engineering,2018,46(1):114-118.