Abstract
The effect of treating viscose rayon by aqueous ethylamine of 73.5% w/w for different treatment times on two dielectric relaxation processes (Ξ³ and Ξ²) observed initially in viscose was studied. Thus, measurements of dielectric constants, Ο΅β², and dielectric loss, Ο΅β³, at frequencies of 0.1β10000 kc/s over a temperature range of 298β333 K, were carried out on four treated samples for 0.5, 1, 2, and 4 h of immersion in ethylamine. Some physical properties were also determined a priori, namely, dissolution and ash content percentages, as well as accessibility toward water and iodine molecules by measurements of heat of wetting and iodine absorption, respectively. In comparison with viscose rayon, the following results were obtained: (i) The Ξ³βrelaxation process was gradually removed by the action of ethylamine, and completely disappeared in samples treated for 2 and 4 h. For this process, the loss, magnitude of polarization, shape parameter, and relaxation frequency decreased with the increase of the time of treatment. (ii) The Ξ²βrelaxation process appeared in all samples investigated over the entire working temperature range. The loss maximum and magnitude parameter decreased with lengthening the time of treatment, whereas the shape parameter and the relaxation frequency increased, all tending toward limiting values over practically the same immersion period of 2β4 h. The results obtained from dielectric measurements, as well as those from other physical measurements, suggested that the viscose fiber obtained after treatment of 0.5 h in ethylamine had acquired some compact structure in the residual low fractions, in which the Ξ³βprocess was supposed to originate, and that further lengthening of the period of immersion resulted, however, in the development of a lessβclosely packed structure in the amorphous regions of the fiber, where the Ξ²βprocess originated. Based on the above, it was finally concluded that the treatment of viscose rayon with ethylamine of the above concentration resulted in several fractions, which vary in the degree of lateral order of arrangement of the chain molecules; i.e., in the relative arrangement of the polar groups in adjacent chains which govern the interchain forces and in turn the dielectric absorption. At the same time, the explanation of the results obtained in this work supports a previous interpretation suggested for the Ξ³β and Ξ²βrelaxation processes in viscose.