Dielectrics have played an important part in the development of modern electrical technology. Most of the organic dielectrics used in industry are based upon polymeric compounds.
From early times man has made use of the polymers that occur in nature, such as wood, leather, cotton, hemp, wool, and silk. In the early days of the electrical industry some of these, for example silk, paper, and rubber, were used as insulating materials; but as the industry developed its demands for materials with improved resistance to electricity and moisture, higher maximum working temperatures, and better dielectric properties at highfrequencies, led to the development of a new branch of science known as polymer chemistry. It was found that materials could be synthesised with predictable physical and chemical properties from simple compounds with low molecular weights, and that the polymers so produced had much better electrical properties than the materials that occurred naturally...

---