Structure

The properties of ion exchange membranes depend on their microstructure, which results from the differences in properties of their ionic and neutral components. The hydrocarbon ion exchange membranes are generally composed of derivatives of styrene-divinylbenzene copolymer and other inert polymers such as polyethylene and poly(vinyl chloride). Ionic derivatives of such copolymers are finely distributed in the inert polymer-forming microdomains because of their poor mutual compatibility. This inhomogene-ity causes the distribution of ion exchange groups in the membrane material to be of varied local concentration. The local distribution of fixed charges can affect all the basic membrane properties, such as electrolyte sorption, electrical conductivity and perm-selectivity as well as mass transport rates. Specifically, a rather unusual structure is characteristic for per-fluorocabon cation exchange membranes (with sulfonic or carboxylic acid groups), which can be classified as ionomer materials. Ionomers and ion-containing polymers with ionic sites and counterions spontaneously organized into dipole multiplets and, for some materials, into larger ion clusters containing 50 or more pairs of ions. These clusters are embedded in the perfluorocarbon membrane backbone, and are connected by narrow channels forming a continuous network.

Despite the heterogeneity resulting from the hydrophilic and hydrophobic nature of membrane components, certain additional morphology features originate from the method of preparation. So-called macroscopically homogeneous membranes can be prepared either by the polymerization of functional-ized monomers or by careful modification of a homogeneous polymer film. However, depending on the method of preparation, the structural imperfection of membranes increases in the following order: interpolymer membranes, graft and block polymer membranes and membranes composed of powdered ion exchange resins embedded thereafter in an inert polymer binder.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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