Preparation and penetrability of microencapsulated phase change materials
Preparation and penetrability of microencapsulated phase change materials
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发表时间：
2006
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通讯作者：
W. Lixin;Ren Xiao-liang
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作者：
W. Lixin;Ren Xiao-liang
通过原位聚合法制备了一种以三聚氰胺脲醛树脂为壳材，以相变材料为芯材的相变材料微胶囊，其熔点和相变焓分别为24℃和225.5J/g。通过改变尿素与三聚氰胺的摩尔比，考察了微胶囊的渗透性和强度。热损伤机理是相变材料在受热时从微胶囊中泄漏出来，壳的破裂是由于芯壳材料在高温下的热膨胀造成的。微胶囊壳的损伤温度可通过热重分析得到。通过扫描电镜观察壳体在压力作用下的表面变化，评价了壳体的强度。采用752分光光度计对微胶囊在乙醇中的透性进行了表征。结果表明，固化溶剂滴入速度小于0.8mL/min时，微胶囊的平均粒径小于5μm，粒径集中。当反应体系中尿素含量为20%（质量分数）时，微胶囊的失重温度可进一步提高至30℃。微胶囊在6.0MPa的压力下不破裂，芯材在乙醇中缓慢泄漏。
Through the in-situ polymerization method,a kind of phase change materials microcapsule was prepared by using melamine-urea-formaldehyde resin as the shell material and a phase change material as the core,of which the melt point and phase change enthalpy are 24℃ and 225.5J/g respectively.The penetrability and strength of microcapsule were investigated by altering the mole ratio of urea to melamine.The thermal damage mechanism is that the phase change materials leak out from the microcapsule when they are heated,and the breakage of the shell was due to the thermal expansion of the core and shell materials at high temperature.The damage temperature of the microcapsule shell can be obtained by TGA.The strength of the shell was evaluated through observing the surface change under pressure by mean of scanning electron microscopy.The penetrability of the microcapsule was characterized in ethyl alcohol by mean of 752 spectrophotometer.As a result,the average diameter of the microcapsule is smaller than 5μm,and the particle size is centralized when the dropping rate of the solidifying solvent is less than 0.8mL/min.The mass loss temperature of the microcapsule can be further enhanced up to 30℃ while the reaction system contains 20%(mass fraction) urea.The microcapsules do not rupture under a pressure of 6.0MPa,and the core material leaks out very slowly from the microcapsule in ethyl alcohol.