Layered structure and viscoelastic properties of wet pulp fiber networks

Viscoelastic properties of wet pulp fiber networks as a function of fiber concentration were investigated with a parallel-plates type rheometer. The dynamic storage moduli, G', of the networks were independent of angular frequency: i.e., they are the pseudo-equilibrium moduli. A power law correlation was found between the moduli and volume concentrations, c_v, of the networks: G' = kc_v^α. The factor, k, changed with the beating degree, which is an index of fiber flexibility. This indicates that the factor, k, reflects the individual fiber characteristics. On the other hand, the exponent, α, was constant and the value was written as three for all the measured fiber networks, regardless of the beating degree. This indicates that the exponent does not reflect the individual fiber properties but the properties of the whole network structure.