Study of electrical conduction mechanisms of the natural rubber by isothermal current depolarization

Abstract

The raw natural rubber is usually extracted from Brazilian rubber trees (Hevea brasiliensis) and is used to manufacture tools such as gloves, sleeves and so on. It is also used in electrically energized line services as electrical energy utilities so customers can be attended without any energy breakdowns. These tools cannot present physical imperfections while in use because they could cause injury or death to electrical workers. Such materials are used as electric insulators and can present a great deal of imperfections during their use in the field due to electrical and mechanical external stressing actions and those can lead to electrical conduction mechanisms and so leading to a dielectric breakdown. In order to improve the quality and durability of the formulated natural rubber compounds for the electric insulation tools used in electrically energized lines, such as gloves and sleeves. Available commercial material from different manufactures was deformulated and reformulated into thin films by thermal press processes in optimized temperature and vulcanization. The reformulated samples have been aged under temperature and in an AC electric field at 3 kHz. The electric conduction mechanism of the samples had been studied by using the isothermal current depolarization technique and the experimental results were analyzed by using dielectric function response models by using Dissado and Hill's theory. Prepared samples in laboratory showed two conduction mechanisms whose parameters of the dielectric function response models involve themselves with the aging processes. To study the two mechanism principles of superposition for the function, it was applied a dielectric response from Dissado and HiIFs theory and an excellent fitting was obtained from experimental data. The obtained results could support one's better understanding of electrical conduction mechanisms of the natural rubber composites that lead the material to a dielectric breakdown, what could develop a better formulation of it so this would guarantee a high quality and durability for the safety tools used in electrically energized lines. This research intends to look into accurate electrical properties of natural rubber composites for practical uses in industry as electrical insulating materials due to the availability of big natural resources in some developing countries what could reduce environmental impact and keep low the prices of raw natural rubber commodities.