...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>polymers for advanced technologies >Crystallization behavior of polyethers containing odd numbers of methylene spacers from the isotropic and liquid crystalline states
【24h】

Crystallization behavior of polyethers containing odd numbers of methylene spacers from the isotropic and liquid crystalline states

机译：Crystallization behavior of polyethers containing odd numbers of methylene spacers from the isotropic and liquid crystalline states

获取原文
           
页面导航
  • 摘要
  • 著录项
  • 相关主题

摘要

AbstractA series of thermotropic polyethers synthesized from 1‐(4‐hydroxyphenyl) ‐ 2 ‐ (2 ‐ methyl ‐ 4 ‐ hydroxyphenyl) ‐ ethane and α,ω‐dibromo‐n‐alkanes with odd numbers of methylene units (MBPE‐n = odd) shows monotropic mesophase behavior. In isothermal differential scanning calorimetry (DSC) experiments, two—sometimes even three—exothermic transition processes can be observed when the crystallization temperature is below the mesophase transition temperature, while only one exothermic process is present above the mesophase transition temperature. The melting behavior of the crystals grown from the mesophase and from the isotropic melt states is different. The crystals grown from the mesophase state exhibit a larger overall heat of transition and a higher transition temperature compared with those grown from the isotropic melt. This may be attributed to the molecular interfacial connections between the crystal and amorphous regions when MBPEs crystallize from the mesophase state. The difference in morphology between the crystals grown from the different states has also been studied with polarized light microscopy (PLM) and transmission electronic microscopy (TEM). The structures of the crystals grown from the different states are, however, the same, as evidenced through wide‐angle X‐ray diffraction (WAXD) measurements. From the banded morphology of MBPE samples observed from PLM, the defect textures observed through TEM and the results of WAXD experiments, this mesophase can be identified

著录项

获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号