纳米铝和石墨烯量子点改性的相变微胶囊的制备及特性
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摘要
本工作旨在探索石墨烯量子点及纳米铝对改善相变微胶囊热性能、悬浮液物理稳定性等特性的作用。以石蜡为芯材、三聚氰胺-甲醛-尿素树脂为壁材,采用原位聚合法制备了三个相变微胶囊样品,分别为不复合石墨烯量子点及纳米铝的样品、复合1.5%石墨烯量子点的样品、复合1.5%石墨烯量子点及7%(质量分数)纳米铝的样品。通过扫描电镜、粒度仪、热传导系数仪、差示扫描量热仪及静置法分别对相变微胶囊的外观、粒径分布、热导率、热物性以及相变悬浮液物理稳定性进行了表征与分析。结果表明,改性微胶囊成型良好,石墨烯量子点的加入有助于提高微胶囊粒径的均匀性,同时复合石墨烯量子点及纳米铝的微胶囊导热系数提高了254.55%,达到0.78 W/(m·K),包覆率提高至92.65%,且相变悬浮液实现了48 h不分层。
This work aimed to explore the modification effects of graphene quantum dots( GQDs) and aluminum nanopowders on thermal properties and physical stability of microencapsulated phase change materials( MPCM). We used paraffin as core and urea-melamine-formaldehyde polymer as shell to synthesize three samples of MPCM,i.e. blank sample with no GQDs & aluminum nanopowders,MPCM incorporated with 1. 5 wt%GQDs,MPCM incorporated with 1. 5 wt% GQDs and 7 wt% nano-aluminum,via an in-situ polymerization. The fabricated MPCM samples were characterized by means of SEM,particle size analyzer,hot disk sensor,DSC,etc. with respect to morphology,particle size distribution,thermal conductivity,thermophysical properties and suspension stability. The results showed that the modified MPCMs all exhibited satisfactory spherical shape,and the introduction of GQDs was conducive to a better particle size distribution. The MPCM sample incorporated with both GQDs and aluminum nanopowders was determined to have a superior thermal conductivity( 0. 78 W/( m·K)) in excess of 254. 55% compared to the ordinary MPCM sample,and a higher encapsulation rate( 92. 65%). Meanwhile,the corresponding suspension can remain unstratified for 48 h.
This work aimed to explore the modification effects of graphene quantum dots( GQDs) and aluminum nanopowders on thermal properties and physical stability of microencapsulated phase change materials( MPCM). We used paraffin as core and urea-melamine-formaldehyde polymer as shell to synthesize three samples of MPCM,i.e. blank sample with no GQDs & aluminum nanopowders,MPCM incorporated with 1. 5 wt%GQDs,MPCM incorporated with 1. 5 wt% GQDs and 7 wt% nano-aluminum,via an in-situ polymerization. The fabricated MPCM samples were characterized by means of SEM,particle size analyzer,hot disk sensor,DSC,etc. with respect to morphology,particle size distribution,thermal conductivity,thermophysical properties and suspension stability. The results showed that the modified MPCMs all exhibited satisfactory spherical shape,and the introduction of GQDs was conducive to a better particle size distribution. The MPCM sample incorporated with both GQDs and aluminum nanopowders was determined to have a superior thermal conductivity( 0. 78 W/( m·K)) in excess of 254. 55% compared to the ordinary MPCM sample,and a higher encapsulation rate( 92. 65%). Meanwhile,the corresponding suspension can remain unstratified for 48 h.
引文
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2 Li W, Wang J, Wang X, et al. Colloid and Polymer Science,2007,285(15),1691.
3 You M, Zhang X X, Wang J P, et al. Journal of Materials Science,2009,44(12),3141.
4 Yamagishi Y. Aiche Journal,1999,45(4),696.
5 Yu S, Wang X, Wu D. Applied Energy,2014,114(2),632.
6 Zhang H, Wang X, Wu D. Journal of Colloid and Interface Science,2010,343(1),246.
7 Fan L, Khodadadi J M. Renewable and Sustainable Energy Reviews,2011,15(1),24.
8 Li M, Chen M, Wu Z, et al. Energy Conversion and Management,2014,83(7),325.
9 Shi J N, Ger M D, Liu Y M, et al. Carbon,2013,51(1),365.
10 Li J, Huang J W, Li Q B. Functional Material,2014,45(S2),110(in Chinese).李军, 黄际伟, 李庆彪.功能材料,2014,45 (S2),110.
11 Wang L, Zhan J G, Liu L, et al. Journal of Heat Transfer,2015,137(2),324.
12 Li Y K, Ma S D, Tang G Y.Functional Material,2010,12(41),1813(in Chinese).黎宇坤, 马素德, 唐国翌.功能材料,2010,12(41),1813.
13 Al-Shannaq R, Farid M, Al-Muhtaseb S, et al. Solar Energy Materials and Solar Cells,2015,132,311.
14 Zhang Z, Zhang J, Chen N, et al. Energy and Environmental Science,2012,5(10),8869.