Dielectric Behaviour of Some Woven Fabrics on the Basis of Natural Cellulosic Fibers

The electrical permittivity of the weaves obtained from natural cellulosic yarns or mixed with synthetic fibers was established with capacitor method. The highest value of relative electrical permittivity in case of the woven fabric from natural cellulosic fibers has been observed at the weave made of pure hemp (13.55) and the lowest at the weave obtained from the pure jute—weave packing (1.87). Electrical permittivity value of the pure jute weave packing is comparable to that of the permittivity for the glass thread, when the work conditions are as follows: temperature 25°C and air humidity 35%. The relative electrical permittivity of the weave is depending on the degree of crimping yarns especially in the weft direction, technological density in direction of the warp and weft, and surface mass of the weave. 1. Introduction Electrical and electrostatic behaviours of the textiles are important for practical applications. Dielectric properties of textile materials have been studied for a long time by many researchers [1–10]. Thus, static friction, one of the main methods of electrification of bodies, was first described by Thales of Miletus (VI century BC) on the basis of observations made by a weaver who found that by rubbing amber with a woolen cloth, it will achieve the property of attracting light bodies [8]. Electrical isolation of current paths of machinery, equipment and electrical installations are made using dielectric materials or electrical insulator, which theoretically have infinite resistivity and appreciable permittivity uninfluenced by environmental conditions and temperature or the variation in time of the electric field where they are used. In real life, insulators have high resistivity, but not infinite permittivity, and properties that vary with the factors previously mentioned and their physical and chemical structure [5–8]. Dielectric materials have the electromagnetic fundamental property to be polarized under the influence of the electric field. Cellulose is one of the dielectrics which can be electronically and structurally polarized, with ionic polarization. The permittivity values of solid dielectrics ？？vary according to the structural features of the dielectric material. Most of the dielectrics with their crystalline structure, although linear, are anisotropic [8]. Natural cellulosic fibers which belong to the category of flax, hemp, jute, and cotton have high hygroscopicity and their electrical properties are closely related to moisture content. Theoretically, the mixing of the natural cellulosic fibers with synthetic fibers