Gas permeation stability of asymmetric polyimide membrane with thin skin layer : effect of polyimide structure
Gas permeation stability of asymmetric polyimide membrane with thin skin layer : effect of polyimide structure
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薄皮层不对称聚酰亚胺膜的气体渗透稳定性：聚酰亚胺结构的影响
DOI：
10.1016/s0376-7388(02)00499-4
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发表时间：
2003
影响因子：
9.5
通讯作者：
S. Nagaoka
中科院分区：
文献类型：
--
作者：
H. Kawakami;K. Nakajima;H. Shimizu;S. Nagaoka
研究了一种非对称聚酰亚胺薄膜的气体渗透稳定性。以不含CF3基团的芳香族二胺和氟化二酐(6FDA)为原料合成聚酰亚胺。采用干/湿相转化法制备了不对称聚酰亚胺薄膜，其表观皮肤厚度为55 nm。用高真空装置测定了35℃、高达760 cmHg的压力下O2、N2、CH4和CO2通过不对称膜的气体渗透率。我们专门研究了皮肤厚度为55 nm的不对称聚酰亚胺薄膜在760 cmHg的二氧化碳压力下的二氧化碳渗透稳定性。在反复渗透实验中，不对称膜的CO2透过率几乎保持不变。此外，在760 cmHg下重复测量的不对称膜的~(13)C T_1值与气体渗透实验前的原始不对称膜非常相似。这些结果表明，不对称聚酰亚胺薄膜的塑化不是由二氧化碳引起的。我们推测芳香族二胺上没有大体积的CF3基团抑制了CO2对聚酰亚胺的塑化作用。
The gas permeation stability of an asymmetric polyimide membrane with a thin and defect-free skin layer has been investigated. The polyimide used in this study was synthesized from the fluorinated dianhydride (6FDA) and the aromatic diamine not containing a CF3group. The asymmetric polyimide membranes were prepared by a dry/wet phase inversion, and the apparent skin layer thickness of the asymmetric membrane was 55nm. The gas permeances of O2, N2, CH4, and CO2through the asymmetric membranes at 35°C and at pressures up to 760cmHg have been determined using a high vacuum apparatus. We specifically focused on the CO2permeation stability of the asymmetric polyimide membrane with a 55nm skin layer exposured to a CO2pressure of 760cmHg. The CO2permeances of the asymmetric membrane showed almost constant values during the repeated permeation experiments. Additionally, the13C T1values of the asymmetric membrane repeatedly measured at 760cmHg were quite similar to those for the original asymmetric membrane before the gas permeation experiment. These results indicate that the plasticization of the asymmetric polyimide membrane was not caused by CO2. We postulated that the absence of bulky CF3groups on the aromatic diamine inhibited plasticization of the polyimide by CO2.