贮热材料新戊二醇-季戊四醇二元体系相图的构筑

Phase diagram of binary system NPG-PE for heat storage material

为了选择适宜的贮热材料,对两种多元醇新戊二醇和季戊四醇利用差示扫描量热(DSC)、X-射线衍射和变温红外光谱技术构筑二元体系相图。结果表明:在一定的组成范围内相图中存在两个低共析温度和一个转晶温度,分别为39℃、163℃和172℃。由于多元醇分子中存在-OH,因而多元醇分子间能形成氢键。随着温度的升高,多元醇发生固-固相变,分子间存在的氢键逐渐受到破坏,-OH伸缩振动的特征吸收波数向高波数发生突跃。变温红外光谱测得的-OH特征吸收峰位移发生突跃的温度区间恰好与体系各自DSC测得的相转变温度相吻合。多元醇的晶体结构、分子的大小是影响二元体系不同相态间互溶度的重要因素。

The phase diagram of the binary system, neopentyl glycol-pentaerythritol （NPC-PE）, was established by three techniques：differential scanning calorimetric （DSC） method, X-ray diffraction and infrared （IR） spectra at various temperatures. Results show that,in a certain composition range, the phase diagram is characterized by two eutectoid invariants, 39℃ and 163 ℃ ,and a crystal transformation temperature,172℃. In the range of temperature closely corresponding to solid-solid transition,the-OH stretching absorption in IR spectra of two polyalcohols and their binary system shift to higher wavenumber. The temperatures of solid- solid phase transition for polyalcohols measured by DSC are consistent with that by IR spectra, which can reveal the mechanism of solid-solid phase transition for polyalcohols. The miscibility of this system is discussed on the basis of intermolecular interaction in ordered low-temperature phase and orientationally disordered high- temperature phase.