Sorption and dielectric properties of jute woven fabrics: Effect of chemical composition

Abstract

The jute woven fabric was treated with sodium hydroxide and sodium chlorite under different conditions in order to study the influence of the chemical composition on their sorption and dielectric properties. After the alkali treatments, the hemicelluloses content decreased in the range of 14.4–46.7%, which leads to elementary fiber liberalization and increased moisture sorption of the jute fabrics up to 15.5% and 11.9% at 30% and 80% relative humidity, respectively. The X-ray diffraction analysis shows that the removal of hemicelluloses for 14.4% and 36.6% was followed by a decrease in the crystallinity index for 3.0% and 18.8%, respectively. The additional decrease in hemicelluloses content of 46.7% was accompanied by a slight increase in the crystallinity index for about 14%. These results are in a good agreement with the results obtained for the AC specific electrical conductivity (at 30% and 80% relative humidity). After the oxidative treatments, the lignin content decreased in the range of 37.8%–79.0%, which causes two parallel effects: a slightly increased moisture sorption (up to 7.4% and 4.6% at 30% and 80% relative humidity, respectively) and crystallinity index (from 4.8%–16.6%). The jute fabrics with 37.8% and 63.2% lower lignin content and similar moisture sorption values have the same AC specific electrical conductivities at both relative humidities (30% and 80%) revealing a dominant effect of moisture sorption. The AC specific electrical conductivity of the investigated jute fabrics increases with increasing the frequency as well as relative air humidity, where the highest difference between the values of AC specific electrical conductivity is obtained at the highest frequency (140 kHz).