偏氟乙烯／三氟乙烯共聚物介电松弛的结晶度效应

用改进的介电松弛谱仪（精度２‰）测定了ＶＤＦ／ＴｒＦＥ（７／２７、６５／３５、５２／４８ｍｏｌ％）共聚物溶液成膜、液氮淬火、熔融慢冷和热处理试样在－１２０—１３０℃、１０－２一１０４Ｈｚ范围的复数介电常数．介电松弛研究结果显示低结晶度的淬火试样较高结晶度的熔融慢冷和热处理试样的Ｔｃ高．结晶度上升，居里点处的介电常数增大．室温以下的介电频率谱分别由代表非晶区分子运动的β松弛（低频部）和局域运动的γ松弛（高频部）叠合而成．随结晶度提高，β松弛峰减小，γ松弛峰增大；非晶松弛强度减弱．晶区松弛强度增强．

EFFECT OF THE DEGREE OF CRYSTALLINITY ON DIELECTRIC RELAXATIONS OF VDF/TrFE COPOLYMERS

he complex dielectric constants of as-cast, quenched, slowly-cooled andallnealed copolymers of vinylidene fluoride with trifluoroethylene (VDF/TrFE) (73/27, 65/35, 52/48 mold )are measured by an improved dielectric relaxation spectrometer in the range of-120-130℃, 10-2-104Hz.The Curie point (Tc) of slowlycooled and annealed samples is lower than that of quenched ones because of a disordered ferrophase in the former and an ordered one in the latter. The dielectricconstant around T. increases with the rise of crystallinity.The frequency spectra ofcopolymers below the room temperature consist of β-relaxation ascribed to the microBrownian motions of molecular segments in the noncrystalline regions and T-relaxation designated as the local motions of small-scale segments. With increasing thecrystallinity,g-relaxation peaks of low-frequency part diminish and γ-relaxation peaks of high-frequency part enlarge, the relaxation strength of noncrystalline decreases and that of crystalline increases.