PORE CHARACTERIZATION IN CELLULOSE BEADS FROM DIFFUSION STUDIES USINGTHE SPIN-ECHO NMR TECHNIQUE

Characterization of the pore structure in cellulose beads is difficult since the pores vary in size, shape and orientation. In this work por e sizes in cellulose beads have been estimated from self-diffusion mea surements using the spin echo NMR technique. Structures were identifie d by measuring the apparent diffusion coefficient at different diffusi on times. The technique was tested using liquid diffusion between glas s beads. The resulting void sizes show good agreement with theoretical predictions. Estimates of the pore sizes in dry cellulose beads of di fferent porosity are found to be in agreement with results from the me rcury intrusion technique. It is concluded that diffusion studies usin g the spin echo NMR technique represent an alternative technique to ch aracterize pore sizes in cellulose beads.