Accurate Measurements of Nonlinear Dielectric Relaxation Spectra of Polymers

聚合物非线性介电弛豫谱的精确测量

基本信息

批准号：
01550704
负责人：
FURUKAWA Takeo
金额：
$ 1.15万
依托单位：
The Institute of Physical and Chemical Research
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550704/
关键词：
Digital fourier transform Dielectric relaxation Nonlinear dielectric spectra Nonlinear conductive spectra Vinylidene cyanide coplymers Polyvinyl acetate Polyethylene oxide 高分子フ-リエ変換

项目摘要

We have developed an apparatus for making accurate measurements of non-linear dielectric relaxation spectra. A sinusoidal electric field with minimal distorsion is applied to a sample and fundamental and higher harmonic dielectric displacements are ditected by means of digital Fourier transform. We obtained linear and third non-linear permittivities as a function of frequency in a 0.01Hz-10kHz range. Using this apparatus, we investigated three kinds of polymers ; vinylidene cyanide copolymers, polyvinyl acetate, and ion-conducting polymers.1. Vinylidene cyanide copolymers, especially with vinyl acetate, have attracted interest past few years because of their very large linear permittivity. Nonlinear didelctric measurements have shown that the third nonlinear permittivity depends upon frequency according to, epsilon_3^*=DELTA epsilon_3/ (1+i omega tau_3) ^3 in accordance with phenomenological prediction. Combined knowledge about DELTA epsilon_1 and DELTA epsilon_3 allow estimates of the … More number and moment of equivalent dipoles. The large permittivities of vinylidene cyanide opolymers are attributed to very large equivalent dipole moments suggesting an existence of strong cooperativity in their molecular motions.2. Polyvinyl acetate is shown to exhibit deformed nonlinear spectra due to the contribution of electrostriction. Additional measurements of the elastic compliance allow subtraction of this contribution to yield the intrinsic nonlinear spectra which are consistent with those observed for vinylidene cyanide coplymers.3. Analogous measurements have been extended to ion-conducting polymers including polyethylene oxide and its derivatives. The results are immediately converted into non-linear conductive spectra to enable discussion on conduction mechanisms of such polymers.On the basis of these results, we have confirmed that the non-linear dielectric spectroscopy in combination with its linear counterpart provides useful information about molecular interaction and dynamics in polymeric systems. Less

我们开发了一种精确测量非线性介电弛豫谱的装置，将畸变最小的正弦电场施加到样品上，并通过数字傅里叶变换检测基波和高次谐波介电位移。使用该装置，我们研究了三种聚合物的非线性介电常数与频率的关系：聚乙烯基氰化物共聚物。 1. 偏二乙烯氰化物共聚物，尤其是乙酸乙烯酯共聚物，由于其非常大的线性介电常数，在过去几年中引起了人们的兴趣，根据 epsilon_3，非线性双介电常数测量表明第三非线性介电常数取决于频率。 ^*=DELTA epsilon_3/ (1+i omega tau_3) ^3 符合现象学预测。结合有关 DELTA epsilon_1 和 DELTA epsilon_3 的知识，可以估计等效偶极子的数量和矩。偏二乙烯氰化物聚合物的大介电常数归因于非常大的等效偶极矩，表明其分子运动中存在强协同性。由于电致伸缩的贡献，醋酸盐表现出变形的非线性光谱，弹性柔量的额外测量允许减去这种对产量的贡献。与偏二氰化物共聚物观察到的本征非线性光谱一致。3．类似的测量已扩展到包括聚环氧乙烷及其衍生物在内的离子导电聚合物。结果立即转换为非线性导电光谱，以便能够进行传导讨论。在这些结果的基础上，我们证实非线性介电谱与其线性对应物相结合提供了有关聚合物体系中分子相互作用和动力学的有用信息。