含微胶囊相变材料的海藻酸钙大胶囊的制备及其性能

采用原位聚合法合成了微胶囊相变材料,并通过锐孔法制备了海藻酸钙包覆多个微胶囊相变材料的大胶囊。用FTIR分析了大胶囊的化学结构,采用游标卡尺测量在不同质量分数的海藻酸钠水溶液和氯化钙水溶液中制备的大胶囊的平均粒径;用SEM和DSC对微胶囊相变材料的微观形貌和热性能进行了分析,对大胶囊的热性能进行了考察,讨论了在不同海藻酸钠质量分数下制备的大胶囊经甲苯萃取30 m in后的热性能。结果表明,微胶囊呈粒径均一,表面光滑,密封较好的球体;其相变温度为34.1℃,相变潜热为143.8 J/g。随着微胶囊相变材料加入量的增加,大胶囊的相变潜热逐渐增加;当w(CaC l2)=2%时,随着海藻酸钠质量分数的增加,大胶囊的粒径由1.36 mm逐渐增加至1.96 mm并趋于平缓,且海藻酸钠水溶液质量分数不宜超过3%;随着氯化钙质量分数的增加,大胶囊平均粒径逐渐增长,但幅度较其随海藻酸钠质量分数变化的幅度小;甲苯对大胶囊壳材的渗透能力随海藻酸钠质量分数的增加而减小。

Preparation and Properties of Calcium Alginate Macrocapsules Containing Microencapsulated Phase Change Material

A microencapsulated phase change material was prepared by the in-situ polymerization,and the macrocapsules composed of calcium alginate as a shell and microcapsules as a core was also prepared by the orifice method.The chemical structure and the average particle sizes of macrocapsules prepared by different sodium alginates and calcium chloride mass fractions were measured by using FTIR and the slide calipers,respectively.The morphology and thermal properties of microcapsules were measured by using SEM and DSC,respectively.In addition,the thermal properties of macrocapsules and the permeability of methylbenzene to the shell of macrocapsules were also measured by using DSC.The experimental results showed that the microcapsules had a regular spherical shape with smooth surface.The phase change temperature and the heat storage capacity of microcapsules were 34.1 ℃ and 143.8 J/g,respectively.The latent heat storage capacity of macrocapsules increased as the microcapsules content increased.The average particle sizes of microcapsules increased from 1.36 mm to 1.96 mm and became flat at last,as the sodium alginate mass fraction increased at the calcium chloride mass fraction of 2%.Meanwhile,the sodium alginate mass fraction can not be more than 3%.The average particle sizes of microcapsules also increased as the calcium chloride mass fraction increased,but the change range was small.The permeability of methylbenzene to the shell of macrocapsules decreased while sodium alginate mass fraction increased.