The uptake and release of humidity by wool irradiated with electron beam

Abstract

In this work, wool samples a) degreased and stored in desiccator (WD), b) degreased and stored freely (WF), c) cleaned in water and stored freely (WW) were irradiated by accelerated electron beam with doses within the range (0-400) kGy in air. Content of S-sulphonate as primary oxidation product was determined in WD using FTIR spectra inverted in the second-order derivative spectra. The uptake of humidity by all the samples at room temperature and 97% relative humidity was examined gravimetrically. As expected, the highest humidity uptake was observed for WD and the smallest one for WW. Development of the humidity uptake showed some fluctuation for all samples and, for WD the fluctuation corresponded with generated S-sulphonate, presumably due to formation of numerous H-bonds. The increasing uptake of humidity for WD and WW was observed up to 40 kGy dose while for WF, the uptake decreased below the initial level already from 16 kGy. Surface tension was measured using sink-float method combining stalagmometry. The initial surface tension of WW was higher than for WD and WF but, grew equally for all samples from 25 kGy. From 100 kGy dose the surface tension showed stabilized level. The humidity release by WD was measured using thermogravimetry. Variation of the rate humidity release around 100 °C, adequate for desorption of weakly bound water, and the mass residue of the heated wool for 120 °C corresponding to release of total water, showed an inverse dependence. It was concluded that content of S-sulphonate is responsible for variability of the sorption properties. The more S-sulphonate formed, the higher uptake of humidity and the lower rate of humidity release that can be observed. It is suggested that, within a certain range, a properly chosen dose can affect humidity uptake.

Time-Dependent Variations in Structure of Sheep Wool Irradiated by Electron Beam

“…Being the generated species of polar character, the correspondent surface energy of the fibres should grow. This parameter was really determined in the degreased and water scoured wool samples [28]. It was found that the surface energy increased immediately already after the lowest dose and became stable from 100 kGy despite the fact that the content of polar groups continued to increase in the bulk.…”

Sheep Wool Humidity under Electron Irradiation Affects Wool Sorptivity towards Co(II) Ions

“…The precipitous deviation of wool moisture from an equilibrium value disrupts the original hydrogen bonds, which must also effect conformational changes in the secondary structure (α-helical, β-sheet, mixed, amorphous structure). Given that there is dual moisture in wool, bound physically and chemically, the process of uptake/release of water runs at a different rate [ 33 ]. In the case of dehydrated wool, recovery of the initial inter- and intramolecular bonds between water and keratin within the following, keeping in conventional laboratory conditions, requires some time.…”

“…Then, new polar functional groups formed by the electron beam effect, but also present without it, can interact with H 2 O more easily. Hanzlíková et al [ 33 ] reported an important increase in the surface energy of electron-irradiated wool. Because the number of new functional groups increases with rising dose, the amount of active sorption sites in the wool increases and rises with time, too.…”