Abstract:

Composed of polystyrene (PS) modified by high thermal conductivity silica (SiO₂) as shell, and n-tetradecane (Tet) as core, a novel PS-SiO₂ @ Tet composite nano-encapsulated phase change material (CNEPCM) for cold thermal energy storage was synthesized by mini-emulsion in-situ polymerization. The morphology, chemical structure and thermal performance of CNEPCM were characterized with particle size analyzer, transmission electron microscope (TEM), X-ray photoelectron spectroscopy(XPS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), respectively. Coefficient of thermal conductivity, specific heat capacity, viscosity and mechanical stability of the synthesized latex were tested. The synthesized CNEPCM with well-defined spherical core-shell structure and z-average particle size of 64.9 nm had high latent heat capacity (T_m 2.13℃, 83.38 J·g^-1) and good thermal stability. Compared with the unmodified emulsion, coefficient of thermal conductivity and specific heat capacity of the synthesized latex were improved as a result of the presence of high thermal conductivity silica, indicating a promising potential functional thermal fluid for cold thermal energy storage.

Key words: composite phase change capsules, nanoparticles, high thermal conductivity silica, heat conduction, cold thermal energy storage fluid, emulsions

摘要：

采用细乳液原位聚合法,研制了以正十四烷(Tet)为芯材、高热导率二氧化硅(SiO₂)改性的聚苯乙烯(PS)为壳层的新型复合纳米相变胶囊蓄冷材料;对复合胶囊形貌、组成以及热物性进行纳米粒度、透射电镜(TEM)、X射线光电子能谱(XPS)、差示扫描量热(DSC)以及热失重(TG)等表征,并测试其乳液的热导率、比热容、黏度及机械稳定性。结果显示:复合相变胶囊平均粒径为64.90 nm,具有规整的球形核壳结构,表面硅含量(质量分数)为3.27%,相变潜热达83.38 J·g^-1,复合壳材对芯材有很好的保护作用;其乳液的热导率及比热容峰值均优于未用SiO₂改性的纳米胶囊乳液,且乳液具有较高机械稳定性和较低黏度,可作为潜在的蓄冷用功能热流体。

关键词: 复合相变胶囊, 纳米粒子, 高导热性二氧化硅, 热传导, 蓄冷流体, 乳液