一种蜜胺树脂为壁材的相变储热微胶囊致密性研究

Study of Compactibility of Thermal Energy Storage Microcapsule with Melamine Formaldehyde Resin as Shell

采用原位聚合法用蜜胺树脂包覆了一种相变点为24℃,相变热为225 5J/g的有机复合相变材料,并对所制备的相变储热微胶囊的致密性进行了研究。利用扫描电子显微镜对微胶囊的表面形态进行了观察;用722型分光光度计对不同工艺条件下所得微胶囊在密度为0.79g/mL乙醇中的渗透性进行了研究;采用压力法观察微胶囊在受压后的表面形貌,对其强度进行了评价。结果表明:相变储热微胶囊呈均匀的球形,表面光滑且致密,平均粒径110μm;由于蜜胺树脂有大的交联密度,微胶囊在乙醇中渗透缓慢,证明芯材包覆效果好,同时发现双层壁材微胶囊的致密性优于单层壁材的微胶囊;平均粒径为10μm的优于平均粒径为1μm的;随着壁材用量的增大,渗透性减弱,但为了保证相变储热微胶囊的储热效果,芯材与壁材质量比以3为好。所制备的微胶囊可以承受1 96×105Pa的压力而不破损。

A kind of heat energy storage microcapsule was prepared using melamine formaldehyde resin as shell material and the compactibility of the shell was investigated.The core is a phase change material,which melts at 24 ℃ and the phase transition heat of which is 225.5 J/g.The surface morphological structure was examined by means of scanning electron microscopy.The penetrability of the microcapsule was characterized in ethyl alcohol (ρ=0.97 g/mL) by means of 722 spectrophotometer.The strength of shell was evaluated through observing the surface change under pressure by means of scanning electron microscopy.As a result,the average diameter of microcapsules was from 1 μm to 10 μm,and the globular surface was smooth and compact.The core material released very slowly from the microcapsule in ethyl alcohol as the melamine formaldehyde had large cross-linking density.It was also found that the compactibility of double-shell microcapsules was better than that of single-shell,and that with average diameter of 10 μm was better than 1 μm.The compactibility decreased with the decrease in shell thickness.The mass ratio of core and shell was chosen to ensure good heat storage function of microcapsules.The microcapsules did not rupture under a pressure of 1.96×10~5 Pa .