Study of Polymer Dynamics by Nonlinear Dielectric Relaxation Spectroscopy

本研究发展了时域和频域的非线性介电弛豫谱仪，并将其应用于具有特殊功能的高分子材料。本文的主要研究内容如下：1.研制了高速、高压矩形电场发生器和电位移检测电路。将这些设备与数字存储示波器和个人计算机相结合，我们研制了时域非线性谱仪，用于观测高电场对上升响应的加速.利用频率合成器、高压放大器、数字存储示波器和微机，研制了用于测量介电响应中基波和谐波的幅值和相位延迟的频域非线性谱仪.利用上述光谱仪，我们测量了偏氟乙烯和三氟乙烯共聚物（铁电、压电聚合物）的非线性介电弛豫谱和聚噻吩（导电聚合物）的非线性电导率谱。在居里点附近的温度范围内观察到的共聚物的非线性介电弛豫谱给出了局部偶极相互作用的信息，对于铁电性的出现是重要的。此外，通过测量聚噻吩在液氮温度到室温的宽温度范围内的非线性电导率谱，我们获得了导电聚合物中导电机制的新信息。

in this study, nonlinear dieletric relaxation spectrometers in both the time and frequency domains were developed and applied to polymers with special functions. A summary of the study is as follows:1. A high-speed, high-voltage rectangular electric field generator and a circuit for detection of electric displacement were fabricated. By combining these equipments with a digital storage oscilloscope and a personal computer, we developed the time-domain nonlinear spectrometer for observing the acceleration of the rise response thme by a high electric field.2. Using a synthesizer, a high-volatge amplifier, the digital storage oscilloscope and the personal computer, we developed the frequency-domain nonlinear spectrometer for detecting the magnitudes and the phase retardations of the fundamental and the harmonics contained in the dielectric response.3. By use of the above spectrometers, we measured the nonlinear dielectric relaxation spectrum of the copolymer of vinylidene fluoride and trifluoro ethylene (ferroelectric, piezoelectric polymer) and the nonlinear conductivity spectrum of polythiophene (conducting polymer). The nonlinear dielectric relaxation spectrum of the copolymer observed in the temperature range around the Curie point gave information on local dipolar interactions important for the appearance of ferroelectricity, Further, by measuring the nonlinear conductivity spectrum of polythiophene in a wide temperature range from liquid nitrogen temperature to the room temperature, we obtained a new information on the conduction mechanism in conducting polymers.