Electrical conductivity Terms Links

Van der Waals molecular. A material that has a very low melting point and that will not conduct electricity either as a solid or when molten consists of molecules that are close-packed, bump-in-hollow and that are attracted to each other by weak van der Waals attractions. Examples include carbon dioxide (CO2, dry ice), iodine (I2), and naphthalene (mothballs). The electrons are constrained to the well-defined groups of atoms that constitute the molecules. The atoms within the molecules are linked together by strong covalent bonds. The weak attractions between the molecules, termed London forces, arise from the charge asymmetry in the molecules that result from the polarizability of their electron clouds. 

A discussion of the chemical drive of solvation and hydration processes, respectively, leads to the introduction of the basic concept of electrolytic dissociation, the disintegration of a substance in solution into mobile ions. Subsequently, we learn about the migration of these ions along an electric potential gradient as a special case of spreading of substances in space. The ionic mobilities provide a link to conductance and the related quantities conductivity as well as molar and ionic conductivity. For determining the conductivity of ions experimentally, the introduction of the term transport number which indicates the different contribution of ions to the electric current in electrolytes is very useful. In the last section, the technique for measuring conductivities is presented as well as its application in analytical chemistry where conductometric titration is a routine method. 

It is well known that the volume change mechanisms in conducting polymers are complex because the electrical, mechanical, and chemical properties of the material, all of which influence the behavior, are closely coupled [67, 69]. This applies to other kinds of electroactive polymers, especially ionic ones. For precise prediction of the deformation response of the materials, these inextricably linked characteristics should be considered. Such model would be useful for long term motion planning of the machines made of such materials. Simple decoupled models which are proposed in this book are aimed to be utilized for machine design and control. Combination of simple and complex models would help us further understanding of the materials and making use of them for machines. 

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