Cathodic swelling

These compounds resemble alkali metal-graphite compounds both in their structure and in their properties. The method used in their preparation was the result of a chance observation in the author s laboratory (80). During an investigation of electrolytic reactions in liquid ammonia a solution of sodium amide in liquid ammonia was electrolyzed with graphite electrodes, and it was found that the cathode swelled and disintegrated. Since the electrodes were not attacked in the solution when there was no electrolysis it was clear that the change could only have... 

Read J, Collins E, Piekarski B, Zhang S (2011) LiF formation and cathode swelling in the Li/CF battery. J Electrochem Soc 158 A504-A510... 

The conformational changes are stimulated by cathodic compaction of the structure, by anodic oxidation and swelling, or, in absence of any external electric field, by thermal energy.177,178,188 In any case, they are a combination of the polymer-solvent interactions. So A can be expressed as a sum of three terms... 

Fig. 1. Bending motion of PAANa gel in dc electric fields. PAANa gel in an NaOH solution swells at the anode side and bends toward the cathode like a bimetal... 

Shiga and Kurauchi have predicted that the swelling deformation of a gel in an electric field is caused by an increase in Flory s osmotic pressure. In order to prove this mechanism, the change in the osmotic pressure under an electric field has been calculated using a simple model for ion transport. The gel and the surrounding solution have been divided into four phases, the A phase (solution at the anode), B phase (gel at the anode), C phase (gel at the cathode), and D phase (solution at the cathode). A mobile cation in a dc field moves toward the... 

Flory osmotic pressures at the anode and cathode sides have been calculated using Eqs. 3-10. In a system of i cations and j anions, the osmotic pressures are given by a summation of Eqs. 3-10. When dn/dt > 0 in an electric field, the gel swells. It shrinks when dn/dt < 0. When n at the anode side becomes larger than that at the cathode side, the gel bends toward the cathode. 

In addition, these authors have discussed the deformation of a PAANa gel placed in contact with the cathode in a dc electric field. Because there is no interaction between the gel and the cathode, the gel swells at the anode side, as observed in the gel separated from the electrodes. It is concluded that the gel also swells at the anode side under an electric field. 

Fig. 5. Time dependence of osmotic pressures at the anode and cathode sides in the hybrid gel. The parameters h and ti represent the transport rates of Na+ from solution to gel and from gel to gel, respectively. When h = h/5, the gel shows anisotropic swelling at the cathode side and bends toward the anode side...

Light microscope (LM) studies showed that ECT caused distinct changes to the cellular structure of treated tumors. In the anodic area, the nuclei shrank and cytoplasmic structure disappeared.37 In the cathode area, the cells swelled and the interface among cells blurred. Repeatedly, one observes swelling in the cathode area (oedema) and dehydration around the anode — this key observation can only be explained in terms of electroosmotically driven water from anode to cathode, to be discussed in details in the Section on Mechanistic Studies. 

Membrane swelling. Such swelling, which is caused by the chemicals present in the anolyte solution, specifically organophosphates such as DMMP, can lead to deformation and mechanical damage as well as contact with the cathode. 

These results Indicate that the degree of volume change due to the uptake of water is related to the resistance of the bond to cathodic action. Tentatively we can conclude from this test, pending further information, that a primer with high resistance to swelling in the presence of OH- and a topcoat with similar volume change behavior in the presence of OH-, will perform best as an adhesive system. 

At least one conclusion can be drawn from all of this. Primers that experience large increases in swelling in the presence of hydroxide ion, despite stability and considerable bond strength in salt water, would probably perform poorly if a cathodic potential was applied. Thus, the qualification of an adhesive system for a marine application that includes exposure of the metal substrate to a cathodic potential, should Include examination of the... 

The swelling of the cathode (CFx) influences the discharge through the formation of a LiF precipitate (23). A film of LiCl is formed on the Li anode by its reaction with the depolarizer SOCI2 this causes the voltage delay during discharge (24). 

Figure 8.12 (a) Responsive swelling ( ) and release ( ) from PSSA-loaded HA hydrogels when an electric field of 10 V cm" was switched off. (Reproduced from R. Tomer et ai, J. Control. Release, 33, 405 (1995).) (b) The effect of an electric field on a polyelectrolyte network. The redistribution of ions causes shrinkage of the gel at the cathode and expansion at the anode. 

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