Molecular mobility in cellulose and paper

作者：Kuttich Bjoern^*; Grefe Ann Kathrin; Kroeling Henri; Schabel Samuel; Stuehn Bernd

来源：RSC Advances, 2016, 6(38): 32389-32399.

DOI：10.1039/c6ra01320a

We study the dielectric relaxation in paper of different density and in microcrystalline cellulose in a temperature range between 150 K and 350 K. Qualitatively the spectra display the same relaxations alpha, beta, gamma. An additional relaxation, beta(wet), is found in humidified samples. The adsorption of water is determined and related to the humidity of the surrounding. Two adsorption processes are identified as primary and secondary adsorption at the hydroxyl groups in the amorphous domains of the cellulose. The g process in the dielectric spectrum is found to be directly related to the amount of water adsorbed in the sample. While qualitatively the differences to unprocessed, microcrystalline cellulose are negligible, quantitatively the less localised beta-relaxation shows an increased relaxation strength induced by the geometrical confinement and orientation effects due to the processing into cellulose fibres. While the manufacturing process leads to paper with different density and porosity there is no significant change in water uptake, structure or dynamics.

• 出版日期2016