Monopolar Membranes

The simplest ion exchange membranes are composed of derivatives of styrene-divinylbenzene copolymers or vinylpyridine-divinylbenzene copolymers. In order to maintain their mechanical strength, these homogeneous membranes are often reinforced by backing materials. Other simple ion exchange membranes can be synthesized from finely powdered ion exchange resin and inert polymer powder applied as a bonding material. Nowadays, more advanced methods of membrane preparation are recommended. The most widely used methods are:

1. Impregnation of a basic polymer component with styrene and divinylbenzene for copolymerization followed by chemical modification (e.g. sulfona-tion);

2. Casting the mixed solution of poly(styrene sulfonic) acid and other inert polymer to produce an interpolymer or 'snake-in-cage' membrane;

3. Radiation grafting of a polymerizable monomer into a conventional polymer film and then introducing the ion exchange groups to the film. The films used are generally polyethylene, polypropylene and perfluoroethylene;

4. Chemical modification: this method involves direct introduction of ion exchange groups to a condensation-type polymer such as polysulfone, poly(ethylene oxide), poly(vinyl chloride), poly(vi-nylidene fluoride), poly(ether ether ketone). The membrane can be formed subsequently by casting the polymer solution, and then phase inversion. The procedure results in an anisotropic membrane structure with a thin skin layer and a supporting layer of sponge morphology;

5. Plasma polymerization. This relatively new method has been utilized to prepare: first, an anion exchange membrane by plasma polymerization of y-aminopropylethoxydimethylsilane on a porous polymer film; second, a perfluorocarbon sulfonic acid membrane, by plasma polymerization of perfluorostyrene and SO2; and third, a thin film sulfonic-type membrane, by plasma polymerization of ethylene and SO2, or acetylene and SO2.

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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