Viscosity of Ionomer Solutions under High Pressure

使用高压滚珠粘度计（S. Sawamura等人，Rev. Sci.仪器，61，871（1990））。在这些实验中，使用Nafion（Du蓬特Inc.）作为离聚物使用，并且99.5%乙醇（Nacalai tesque Inc.）用作极性有机溶剂。制备了8种不同浓度的溶液。测量在25.0 ℃和高达300 MPa下进行。聚电解质效应，这是众所周知的，在普通的极性有机溶剂的水溶液中，观察到在这些离聚物溶液在常压下。也就是说，稀溶液的粘度随着样品溶液浓度的降低而增加。在高压下也观察到了双折射效应。然而，随着压力的增加，这种影响被抑制。类似的行为，。也就是说，在大气压下，在其它离聚物溶液中，其它工作者已经报道了通过加入少量的简单盐来抑制离子效应。但本研究首次观察到离聚体溶液粘度的压力依赖性以及随着压力的增加离聚体溶液粘度效应受到抑制的现象，由于实验刚刚结束，很难描述对本研究结果的考虑。但证实了以下几点：（1）在高压下观察到聚电解质效应;（2）随着压力的增加，聚电解质效应受到抑制。这里观察到的抑制可以解释由稀溶液中的聚合物离子的形状变化。溶剂的介电常数随压力的增大而增大，这可能是抑制溶剂的介电效应的重要原因。

Viscosity measurements of ionomer solutions under high pressure were made using a high pressure rolling-ball viscometer(S. Sawamura et al., Rev. Sci. Instrum., 61, 871(1990)). In these experiments, Nafion(Du Pont Inc.)was used as an ionomer, and 99.5 Vol % ethanol(Nacalai tesque Inc.)was used as a polar organic solvent. The 8 kinds of different concentration solutions were prepared. The measurements were carried out at 25.0 ﾟC and up to 300 MPa. Polyelectrolyte effect, which was well known in ordinary polyelectrolyte solutions of polar organic solvent, was observed in these ionomer solutions under atmospheric pressure. Namely, the viscosity of the dilute solution increased with decreasing concentration of the sample solutions. The polyelectrolyte effect was also observed under high pressure. However, the effect was suppressed with increasing pressure. The similar behavior, . that is, the suppression of the- polyelectrolyte effect with adding a small amount of simple-salt was reported already by other workers in the other ionomer solutions under atmospheric pressure. But the pressure dependence of the viscosity of the ionomer solution and the suppression of the polyelectrolyte effect with increasing pressure were first observed in this study.Since the experiments have just finished, it is difficult to describe the considerations of the results of this research. But the followings were confirmed : (1)Polyelectrolyte effect was observed under high pressure, (2)The polyelectrolyte effect was repressed with increasing pressure. The repression observed here may be explained by the shape change of the polymer ions in the dilute solution. And the increment of dielectric constant of the solvent with increasing pressure may play important role for the repression of the polyelectrolyte effect.