物理化学学报 >> 1989, Vol. 5 >> Issue (01): 62-66.doi: 10.3866/PKU.WHXB19890113

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液晶HpBAB的相变和熔化熵的同系规律性的热力学研究

王邦宁;谈夫   

  1. 中国科学院化学研究所，北京
  • 收稿日期:1987-09-17 修回日期:1988-02-22 发布日期:1989-02-15
  • 通讯作者: 王邦宁

Thermodynamic Study of the Phase Transitions of the Mesogen HpBAB and the Homologous Trend of the Melting Entropies

Wang Bang-Ning;Tan Fu   

  1. Institute of Chemistry, Academia Sinica, Beijing
  • Received:1987-09-17 Revised:1988-02-22 Published:1989-02-15
  • Contact: Wang Bang-Ning

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摘要： 在260～380 K范围内, 用DSC法研究液晶HpBAB的相变。实验查明HpBAB在室温还以玻璃性晶体状态存在。它的玻璃转变、熔化和清亮过程的热力学参数准确地被测到。提出对-正烷氧基亚苄基-对-氨基苯腈同系列中熔化熵和烷基碳原子数的线性关系; 改进Aranow统计模型并估算直线斜率为Rln(3/g)(1

Abstract: The phase transitions of N-(p-n-heptyloxybenzylidene)-p'-aminobenzonitrile (H_pBAB) were studied at various rates within the range 260—380K by DSC. It was revealed by the DSC experiments that the thermotropic nematogen H_pBAB obtained by the repeated recrystallization from absolute ethanol was the glassy crystal at room temperature in addition to the known stable and metastable crystal modifications K(Ⅰ) and K(Ⅱ). This is the first example of glassy crystal among the mesogens in so far as author's knowledge. The temperature and the heat capacity step of the glass transition of H_PBAB are 327.05±0.41 K and 310±27 J K~(-1) mol~(-1), respectively. Its melting temperature and enthalpy and entropy of fusion are 341.16±0.14 K, 32.78±0.22 kJ mol~(-1), 96.07±0.66 J K~(-1) mol~(-1) fro the crystal-I; 332.65±0.25 K, 22.66±0.99 kJ mol~(-1) for the metastable crystal-II, ....