中华医学超声杂志

应用化学 ›› 1994, Vol. 0 ›› Issue (2): 7-12.

• 研究论文 • 上一篇    下一篇

铁电共聚物VDF/TrFE的低温低频介电松弛

张兴元1, 古川猛夫2   

  1. 1. 中国科学技术大学材料科学与工程系 合肥 230026;
    2. 理化学研究所 日本
  • 收稿日期:1993-07-20 修回日期:1993-12-15 出版日期:1994-04-10 发布日期:1994-04-10

Dielectric Relaxation of VDF/TrFE Copolymer Ferroelectric at Low Temperature and Frequency

Zhang Xingyuan1, Takeo Furukawa2   

  1. 1. Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026;
    2. The Institute of Physical and Chemical Research, Japan
  • Received:1993-07-20 Revised:1993-12-15 Published:1994-04-10 Online:1994-04-10

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摘要： 在低温低频下用介电松弛方法研究了液氮淬火、熔融慢冷和热处理结晶铁电共聚物VDF(73)/TrFE(27)的分子运动特征。随结晶度升高,居里点温度降低,铁电-顺电相变区的介电常数增大。室温以下共聚物的频率谱由低频和高频两部分组成。低频部由非晶区被冻结分子链段的微布朗运动贡献;高频部则由晶区和非晶区分子链段较小尺度的局域运动产生。由两个Cole-Cole函数对频率谱进行分峰拟合并根据WLF方程和Arrhenius表达式计算得到的共聚物玻璃化转变温度为-37℃,局域松弛活化能为48.8kJ/mol.

关键词: 偏氟乙烯, 三氟乙烯, 共聚物, 分子运动, 介电松弛

Abstract: The characteristics of molecular motion of the vinylidene fluoride (73)/trifluoro ethylene(27)copolymer ferroelectric have been investigated by dielectric relaxation measurements at low temperatures and low frequencies. With increase of the crystallinity of the copolymer, the Curie-point temperature Tc decreased and the dielectric constant increased in the region of ferroelectric-paraelectric phase transition. The frequency spectra of the copolymers below room temperature consisted of a low-frequency part ascribed to the micro-Brownian motion of molecular segments in the noncrystalline regions and a high-frequency part designated as the local motions of small-scale segments. The Tg(=-37℃) and △H(=48.8kJ/mol) of copolymers were obtained from the fitted results using two Cole-Cole functions and calculation with WLF equation and Arrhenius formula respectively.

Key words: vinylidene fluoride, trifluoroethylene, copolymer, molecular motion, dielectric relaxation

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