Search

In this work, sorption and dielectric properties of viscose/polypropylene multipurpose nonwoven fabrics were examined. The analysis of sorption behavior showed that the changes of the water absorptive capacity, the height of capillary rise and water retention value are in a function of viscose fiber content, total porosity, the pore size and used web bonding process. It is observed that dielectric properties at frequencies from 30 Hz to 140 kHz, for samples exposed to different relative air humidity and wet samples, are dependent on viscose fiber content, web bonding process, frequency of electric field and bulk free water content. The effective dielectric permeability of wet samples rapidly decreases with an increase in frequency up to 3 kHz while spectra of the AC specific electrical conductivity showed a plateau above 13 kHz. It is also observed that the dielectric properties of wet samples increase by several orders of magnitude compared to dry samples.

Plasma treatment of viscose cellulose fabric was performed using the atmospheric pressure dielectric barrier discharge (DBD) in nitrogen. Samples were treated using nonthermal plasma, and change of sorption properties with plasma energy density was investigated. It was found that using low energy of discharge, modified viscose samples become less hydrophilic and their wettability is significantly reduced. The observed hydrophobic effect was investigated and confirmed throughout series of experiments, by measuring a change in wetting time and in the level of aqueous liquid repellency. Structural changes were monitored using SEM, AFM, and XPS. It was established that increase of roughness combined with removal of hydrophilic polar groups from the surface of cellulose using plasma represents a novel approach to impart hydrophobicity onto hydrophilic textile. An additional binding of copper ions to nitrogen DBD treated cellulose produces a cross-linking effect, i.e., an occupation of remaining hydrophilic groups on the fabric surface and provides so called “petal effect” where drops of water stick to the fabric surface when the fabric is tilted for 180°. This novel procedure for obtaining hydrophobic cellulose could be used for a preparation of special protective textile materials with cost and time effective methods and chemicals.