不同乳化剂种类和浓度对正十八烷@碳酸钙相变微胶囊的性能影响

The Effect of Different Emulsifier Types and Concentrations on the Performance of N-octadecane@CaCO_(3) Phase Change Microcapsules

采用自组装法成功制备了以正十八烷为芯材,碳酸钙(CaCO_(3))为壁材的相变微胶囊复合材料。用傅里叶变换红外光谱(FTIR)、X射线衍射仪(XRD)和扫描电子显微镜(SEM)表征了相变胶囊的化学组成和形貌,差示扫描量热仪(DSC)、热重分析仪(TG)和导热系数仪(TCM)对其热性能进行了表征。制备过程中,乳化剂的种类与浓度影响CaCO_(3)壳的相貌,微胶囊包封率、热稳定性以及热导率等性质。当乳化剂为十二烷基苯磺酸钠(SDBS)时,形成的CaCO_(3)壳为球霰石相;乳化剂为十二烷基硫酸钠(SDS)时,球霰石和方解石相均生成。DSC和TG结果表明,与SDS作为乳化剂制备的微胶囊相比,SDBS制备的微胶囊包封率更高,但热稳定性有一定下降。制备得到的正十八烷@CaCO3相变微胶囊热导率比正十八烷的热导率最高可增加497.3%。当SDBS的摩尔浓度为0.75 mol/L时,制得的相变微胶囊材料的包封率可达到35.5%,热导率可提高290.7%。综上,SDBS更适合作为乳化剂用来制备用于热能存储的正十八烷@CaCO_(3)相变微胶囊。

A phase change microcapsule composite material with n-octadecane as the core material and calcium carbonate(CaCO3)as the shell material was successfully prepared by the self-assembly method.The chemical composition and morphology of phase change capsules were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffractometer(XRD)and scanning electron microscopy(SEM).The thermal properties were characterized by differential scanning calorimetry(DSC)、thermogravimetric analyzer(TG)and thermal conductivity meter(TCM).During the preparation process,the type and concentration of the emulsifier affected the appearance of the CaCO_(3)shell,encapsulation efficiency,thermal stability and thermal conductivity.The CaCO_(3)shell was formed in the vaterite crystalline phase when the emulsifier was sodium dodecylbenzene sulfonate(SDBS).When sodium dodecyl sulfate(SDS)was used as an emulsifier,both vaterite and calcite were formed.DSC and TG results show that,compared with microcapsules prepared by SDS as an emulsifier,the encapsulation efficiency of microcapsules prepared by SDBS is higher,but the thermal stability is somewhat reduced.The thermal conductivity of the prepared n-octadecane@CaCO_(3)phase change microcapsules can be increased by up to 497.3%compared with the n-octadecane.When the molar concentration of SDBS is 0.75 mol/L,the encapsulation efficiency of the prepared phase change microcapsule material can reach 35.5%,and the thermal conductivity can be increased by 290.7%.In summary,SDBS is more suitable as an emulsifier to prepare n-octadecane@CaCO_(3)phase change microcapsules for thermal energy storage.