The Application Of The Electrochemical Impedance Spectroscopy In The Study On The Structures And The Properties Of Composites

The electrochemical impedance spectroscopy is a quasi-steady-state method. It can give more dynamic informations and interface structure informations that other conventional electrochemical methods can not give. Therefore, it is widely used in the materials researches.The composites are the materials that composed of more than two components with a certin amount which are selected. The composites are the artificial compounds with multiphases, three-dimensional integration, clear interface between each phase, and the special properties. The relationship between the structures and properties of composites is close.Cu/LDPE composites and ZnO/WO3 nanocomposites both belong to the composites. Cu/LDPE composites are metal/polymer composites. It is a novel Cu-IUD material that can overcome the shortcomings of traditional Cu-IUDs. ZnO/WO3 nanocomposites belong to the nano functional composites.They are widely used as photocatalytic materials.In order to investigate the relationship between the interface property and the Cu2+ release property of Cu/LDPE composite, the electrochemical impedance spectroscopy was used to obtain the interface property. The microstructure characteristics and the equivalent circuit of pure LDPE and Cu/LDPE composites that immersed in the solutions for different periods were presented.The electrochemical impedance spectroscopy and Cu2+release results showed that with the increasing of the content of copper particles in the composites the interface between polyethylene and the solution increased. That resulted in the interface resistance {Rint) increasing and the interface capacitance (Cint) decreasing. The release rate of cupric ions increased with the increasing of the interface. The interface between polyethylene and the solution in the microcomposites was more than that in the nanocomposites with the same copper content. The interface resistance in the microcomposites was larger and the interface capacitance in the microcomposites was smaller than that in the nanocompsoites. When the concentration of copper particles in the composite was high, the release rate of cupric ions in the microcomposite was larger than that in the nanocomposite.When the nanocomposite with 25 wt.% copper nanoparticles immsered in Solution A (pure water), Solution B (containing normal salts with CI-), Solution C(containing B and NaHCO3), Solution D (containing C and NaH2PO4), and Solution E (containing D and glucose), the change of the interface resistance (Rint) and the interface capacitance (Cint) between LDPE and the solution in the solutions were that Rint(A)[Rint(B),Rint(C),Rint(D)]Cint(E). The order of the diffusion impedance in the solutions was that Zw(B)