Characterization of different types of cellulose by dielectric spectroscopy

Various 'well dried' solid celluloses, such as native celluloses from different sources, different pulps and regenerated cellulose fibers were compared by dielectric relaxation spectroscopy (DRS) in the low frequency (10 mHz to 5 MHz) and low temperature (-130 to 20degreesC) range. No significant differences were found in the polymeric dynamics. In addition, the influence of the water content on the beta-relaxation and the beta(wet) relaxation was investigated for morphologically very different celluloses such as cotton linters, highly amorphous bead cellulose and lyocell fibers. The lyocell fibers were investigated in the unmodified form and after modification by a treatment with alkali, after mild bleaching and after chemical crosslinking. It was found that the water content influences the dielectric dynamics and the intensity parameters differently for these different materials. NaOH- activation using different lye concentrations also influenced the dielectric dynamics. Finally, opportunities and limitations of DRS as a diagnostic tool are discussed.