同轴气喷法制备海藻酸钠-十六烷相变微胶囊

Preparation of Sodium Alginate-Cetane Phase Change Microcapsules with Coaxial Jet Method

以海藻酸钠为壁材,十六烷为芯材,使用同轴气喷法制备相变微胶囊,考察了液体及气体流量对微胶囊粒径及壁厚的影响规律;采用光学显微镜、差示扫描量热(DSC)、热重分析(TG)等测试了微胶囊的平均粒径、包覆量、热稳定性及储热性能。结果表明同轴气喷法制备微胶囊的步骤简单,粒径的可控性较强。能够通过调节内、外管流量和气体流量控制微胶囊的粒径及壁厚。所制得的微胶囊粒径随液体流量减小而减小,随气体流量增大而减小。当海藻酸钠溶液流量为4 mL·h-1,十六烷的流量为2 mL·h-1,气体流量为25 L·h-1时,制得的相变微胶囊最小,其平均粒径约为90μm。相变微胶囊的囊芯包覆量随粒径的减小而减小,当微胶囊粒径约为300μm时,其包覆量达到90%以上。海藻酸钠囊壁对相变材料的储热性能不产生显著影响。

Sodium alginate-cetane phase change microcapsules were prepared by coaxial jet method aided by gas spray. The produced microcapsules were characterized by microscope, differential scanning calorimetry （DSC） and thermogravimetry （TG） to investigate their morphology, mean size, heat stability and heat storage properties. Compared to the approach of other microencapsulation methods, the new technique is not only simple but also provides an effective way of size control. Experimental results show that the size and shell thickness of the microcapsules could be controlled by adjusting flow rates of core and shell fluids as well as the gas flow rate. The particle size decreases with liquid flow rate, and decreases with increasing gas flow rate. When the sodium alginate solution flow rate is 4 mL·h-1, cetane flow rate is 2 mL·h-1, and 25 L·h-1 for gas flow, the average size of the phase change microcapsules reaches a minimum of 90 μm. The core coated ratio of phase change microcapsule decreases with the decrease of the particle size. When the microcapsule particle size is about 300μm, the core coated ratio is more than 90%. The wall material of sodium alginate does not influence the heat stability and heat storage properties of phase change materials.