丹宁酸刻蚀ZIF-67制备导热增强型定形相变材料的性能

Thermal storage performance of shape stabilized phase change materials with high thermal conductivity derived from ZIF-67 etched via tannic acid

为解决有机固-液相变材料(PCMs)导热系数低和相变易泄漏的难题,利用丹宁酸刻蚀ZIF-67制备碳基骨架作为支撑体(HX-C),硬脂酸(SA)为相变芯材,采用真空熔融吸附法构筑导热增强型定形相变材料(SA/HX-C)。为评估其储热能力,对热稳定性、储热性能、导热系数、定形能力及光热转换能力进行研究。同时,借助氮气等温吸附-脱附、傅里叶红外光谱、X-射线衍射和扫描电子显微镜进行表征。结果表明:丹宁酸刻蚀ZIF-67可实现对其碳化衍生物的扩孔作用,提高SA/HX-C的定形能力。所制备的SA/HX-C具有良好的储热性能、导热能力及光热转换性能。其中,刻蚀时间为6 min的复合相变材料(SA/H6-C)的储热效率可达80.84%,光热转化效率高达76.29%,导热系数(0.461 W/(m·K))相比于SA提高了156.11%。SA/H6-C在相变过程中无任何形貌变化和泄漏,重复循环储/放热100次后仍然具有良好的储热能力。

To solve the defects of low thermal conductivity and leakage of organic solid-liquid phase change materials(PCMs),ZIF-67 was etched by tannin acid to obtain the carbon-based supports(HX-C),stearic acid(SA)was the phase change material and then used to prepare the enhanced thermal conductivity PCMs(SA/HX-C)via vacuum melting adsorption method.In detail,thermal stability,heat storage property,thermal conductivity,shape stability and photo-thermal conversion were investigated to evaluate the thermal storage performance.Meanwhile,characterizations of nitrogen isothermal adsorption-desorption,FTIR,XRD and SEM were conducted.Results revealed that tannic acid can expand the pore size of carbonized ZIF-67 derivatives,thus enhancing the shape stability.The obtained SA/HX-C own favorable heat storage property,thermal conductivity,and photo-thermal conversion.Among them,etching time of 6 min for PCMs(SA/H6-C)exhibits high thermal storage efficiency of 80.84%and photo-thermal conversion of 76.29%.Thermal conductivity is strengthened to 0.461 W/(m·K),which is 156.11%higher than that of SA.No leakage and shape change are observed for SA/H6-C during phase transition,it still shows good thermal storage performance even after recycling 100 times.