Multipurpose Nonwoven Viscose/Polypropylene Fabrics: Effect of Fabric Characteristics and Humidity Conditions on the Volume Electrical Resistivity and Dielectric Loss Tangent

In this work, the volume electrical resistivity and dielectric loss tangent of viscose/polypropylene multipurpose nonwoven fabrics were examined. According to the obtained results, the changes in the volume electrical resistivity depend on the applied chemical bonding agent, viscose fiber content, moisture content, fabric thickness, fabric weight, and relative air humidity. Based on the volume electrical resistivity hysteresis, the portion of sorbed moisture retained in the material after desorption, as well as the portion of moisture removed from the material during desorption, were determined. Furthermore, the dielectric loss tangent measured at the frequency range between 30 Hz and 140 kHz, for the samples exposed to different relative air humidity (40 % and 80 %) and wet samples, is dependent on the chemical bonding agent, viscose fiber content, moisture content, as well as frequency of the external electric field. The dielectric loss tangent measured at 80 % relative air humidity showed a peak at about 100 Hz, while for the wet samples, the peak was observed in the frequency range between 30 and 140 kHz. In a wet state, the dielectric loss tangent is primarily influenced by the water molecules present in the sample.