【摘要】 多元醇在固-固相变时能够可逆地吸收大量的热而被用做贮热材料,特别是三羟甲基乙烷(PG)和三羟氨基甲烷(TAM)构成的二元体系,有很宽的适宜于太阳能贮存的温度范围。为了材料的选择,现利用差热分析(DTA)、X-射线衍射及变温红外光谱技术测定了PG-TAM二元体系相图。确定后的相图表明,从室温升温至熔化的过程中,相图在一定的组成范围内出现了三个低共熔点,分别为71℃、111℃和165℃。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DTA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。更多还原

【Abstract】 Polyalcohols exhibit crystalline transformation which reversibly absorb large amount of heat and can be used for thermal energy storage. The experimental phase diagram of binary system trimethylol ethane-tris(hydroxymethyl)aminomethane(PG-TAM) was established by three kinds of techniques: differential thermal analysis(DTA) method, X-ray diffraction and IR spectra at various temperatures. The phase diagram is characterized by three eutectoid invariants of 71℃、111℃ and 165℃. Infrared spectra of two polyalcohols and their binary system at room temperature show a strong absorption centered at 3347cm?1 which is identified as the -OH stretching band and indicates that between molecules there are hydrogen bonds which play a dominant role to the structure of the low temperature phase. In the temperature range closely corresponding to the solid-solid phase transition, -OH stretching band shifts to a higher wavenumber, which indicates that the hydrogen bands between molecules are broken. The temperatures of solid-solid phase transition for polyalcohols measured by DTA method are consistent with the results of IR which can declare the mechanism of solid-solid phase transition for polyalcohols. The miscibility of this system was discussed on the basis of intermolecular interactions between ordered low-temperature phase and orientationally disordered high-temperature phase.更多还原