Acta Phys. -Chim. Sin. ›› 1997, Vol. 13 ›› Issue (03): 207-211.doi: 10.3866/PKU.WHXB19970305

• Communication • Previous Articles     Next Articles

Study on the Water Sorption of an Epoxy Coating Using Electrochemical Impedance Spectroscopy

Zhang Shu-Yong,Luo Xiao-Wen,Li Shan-Jun,Zhou Wei-Fang   

  1. Department of Chemistry,Department of Macromolecular Science,Fudan University,Shanghai 200433
  • Received:1996-11-22 Revised:1996-12-30 Published:1997-03-15
  • Contact: Zhou Wei-Fang


The amount of water sorption of an epoxy coating can be determined approximately by measuring the electrochemical impedance spectra of both an Al electrode coated with the epoxy film and a preliminary wetted Al electrode covered tightly with the epoxy film. By comparing the double layer capacity of these two electrodes, the amount of water sorption can be estimated. The resistivity of the electrolytic solution in the film may by thousands times larger than that of the bulk solution. This is due to the fact that the cross-section area of the water passages in the film is of molecular size. The short-distance interaction between the ions and the wall of the water passage retards the transport of the ions seriously. The structure of the water passages is discussed.

Key words: Epoxy coating, Electrochemical impedance spectroscopy, Water sorption of epoxy film