Test methods electrochemical aspects

An electrochemical method projected for the determination of the effective volume of a colloidally dispersed polyelec-trolyte phase in aqueous media was evaluated. Experiments with the highly flexible Sephadex (carboxymethyldextran) gel and the more rigidly cross-linked polymethacrylic acid resin were performed for this purpose. With the well-defined resin (gel) phase it was possible to measure the polymer volume as a function of every experimental condition used to test fully the fundamental concepts on which the method is based. The results substantiate the validity of concepts developed. Application of this method for estimating the effective volume of weakly acidic (basic) polymers in solution seems worthy of further consideration. However, some modification of the treatment of the electrochemical data is necessary for polymeric sols, and this aspect is discussed briefly. 

Electrochemical methods have been used in corrosion testing ever since the electrochemical nature of corrosion processes was discovered. In the present age electrochemical measurements involve the use of sophisticated black boxes which are invariably blamed for any pitfalls which occur. Hence the European Federation of Corrosion Working Party on Physicochemical Methods of Corrosion Testing felt it desirable to remind research workers, students and instrument designers of the more fundamental aspects of the measurements. 

The electrometer has very high input impedances with respect to voltage measurement and zero input impedance with respect to current sensing along with high precision and resolution. Here we focus on the aspects of this potentiodynamic technique. Aspects of instrumentation are beyond the scope of this chapter. There are several other pseudo-steady state methods that are often used in other electrochemical systems. Some I-V tests include ... 

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