Analysis on Anormarou Crystallization and mum-Size Pores Formation Mechanism of Triglycerides

用X射线衍射和散射、红外显微镜、拉曼散射和显微镜观察等方法研究了三棕榈酸甘油酯的结晶过程。其结晶行为明显依赖于结晶温度Tc，如下：Tc<40 ℃：α，45<Tc<50 ℃：β '和Tc<50 ℃：β。具有T//型亚晶胞的稳定相β相在51-55 ℃温度范围内表现出异常结晶。虽然B的单晶最初以板状晶体逐渐生长，但生长速率突然增加，晶体以块状晶体生长。可以清楚地看出，当出现块状晶体时，由于结晶而导致的密度快速增加之后，发生密度的快速降低。密度降低是由于晶体中出现缺陷所致。X射线衍射和散射实验表明，β相与块状β相没有本质区别，但在试样中产生了许多毫米级的气孔，β相可分为两个相，b1相由溶液和熔体结晶得到，β 2相由α * β固态转变得到。偏振红外光谱表明，两个β相的甘油主链的构象不同。

Crystallization process of tripalmitin has been studied by means of X-ray diffraction and scattering, IR microscope, Raman scattering and microscope observation. Its crystallization behavior dependes markedly on crystallization temperature Tc as follows ; Tc<40ﾟC : alpha, 45<Tc<50ﾟC : beta', and Tc<50ﾟC : beta. The beta phase, which is the stable phase and has T//type subcell, shows an anomalous crystallization in the temperature region of 51-55ﾟC.Although a single crystal of b gradually grows as plate crystal initially, the growth rate increases abruptly and the crystal grows as a massive crystal.By specific volume measurement using dilatometry, it is clarified that a rapid decrease in density takes place after a rapid density increase due to crystallization when a massive crystal appears. The density decrease comes from the occurrence of defects in the crystal. The X-ray diffraction and scattering experiment showed that there was no essential differences between the usual beta crystal and the massive beta crystal and that many mm-size pores had been generated in the specimen.This study has revealed also that the beta phase can be classified into two phases ; b1 obtained by solution and melt crystallization and beta2 obtained by the alpha*beta solid-state transition. Polarized IR spectra showed that the two beta phases differ in the conformation of the glycerol backbone.