Watanabe Kaito, Ikeda Junko, Zhong Xianzhu, Zhou Jiabei, Kaneko Tatsuo, Kawai Mika, Mitsumata Tetsu
Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
Mageleka Japan Co., Ltd., Kashiwa 277-0882, Japan.
Polymers (Basel). 2025 Jan 11;17(2):167. doi: 10.3390/polym17020167.
Transitions seen in the electric properties of water-absorbable poly(2,5-benzimidazole) (ABPBI) films were confirmed by electric conductivity, dielectric constant, and time-domain nuclear magnetic resonance (NMR) measurements. The electric resistance of the films was measured at room temperature using a high-resistance meter, and the dielectric constant at room temperature was measured using an LCR meter in the frequency range of 90 Hz to 8 MHz. The water absorption ratio at equilibrium absorption for the films was 37%, which corresponded to a volume fraction of water of 0.33. The electric conductivity of the films without water absorption was ~10 S·cm, and it increased to ~10 S·cm with increasing volume fraction, showing a percolation threshold at a volume fraction of 0.025, and remarkable transitions at volume fractions of 0.075 and 0.135. The dielectric constant of the films without water absorption was 3.4, and it increased to 8.1 with increasing volume fraction, showing a transition only at a volume fraction of 0.135. Above a volume fraction of 0.075, where a transition in conductivity was observed, there were two relaxation times at 18-31 μs and 20-93 μs, as determined from the time-domain NMR, and these relaxation times increased with increasing volume fraction. The longer relaxation time increased significantly at a volume fraction of 0.072, which was close to the volume fraction of the transition seen in conductivity. The relationship between the chain mobility of ABPBI and the deterioration in electric insulating properties is discussed.
通过电导率、介电常数和时域核磁共振（NMR）测量，证实了吸水性聚（2,5-苯并咪唑）（ABPBI）薄膜电性能的转变。使用高电阻计在室温下测量薄膜的电阻，使用LCR计在90Hz至8MHz的频率范围内测量室温下的介电常数。薄膜在平衡吸收时的吸水率为37%，这对应于水的体积分数为0.33。未吸水薄膜的电导率约为10S·cm，随着体积分数的增加，电导率增加到约10S·cm，在体积分数为0.025时出现渗流阈值，在体积分数为0.075和0.135时出现明显转变。未吸水薄膜的介电常数为3.4，随着体积分数的增加，介电常数增加到8.1，仅在体积分数为0.135时出现转变。在体积分数高于0.075（观察到电导率转变的地方）时，根据时域NMR测定，有两个弛豫时间，分别为18 - 31μs和20 - 93μs，并且这些弛豫时间随着体积分数的增加而增加。较长的弛豫时间在体积分数为0.072时显著增加，该体积分数接近电导率转变时的体积分数。讨论了ABPBI的链迁移率与电绝缘性能劣化之间的关系。
