POROUS STRUCTURE OF CELLULOSE FIBER WALLS STUDIED WITH NMR DIFFUSOMETRY

摘要

By performing an array of NMR experiments, including diffusometry and relaxometry, on hydrated cellulose samples we can observe water with different properties. Water inside and outside the fiber wall is separated with the CPMG experiment. Water residing in nm-scale and μm-scale pores inside the fiber wall is separated with self-diffusion measurements. The results of this study are summarized in Figure 5. At high MC all types of water are present. Drying removes water between the fibers until this water disappears at MC_1. Further drying removes water from the μm-scale pores until they are closed at MC2. For the kraft pulp samples MC_1 = 0.25 g/g and MC_2 = 0.7 g/g. For viscose MC_1 = MC_2 = 0.7 g/g.