VISCOELASTIC BEHAVIOR OF DILUTE FIBER SUSPENSIONS

The complex shear modulus of dilute suspensions of cellulose fibers has been measured as a function of frequency in the low acoustic range. The experiments have been carried out with different types of fibers and at various concentrations, in suspending liquids of viscosity between 0.05 and 2 P. The qualitative dependence on ω of G′ and η′ is similar to that of other viscoelastic systems, more particularly to solutions of linear macromolecules. The shear modulus G′ is very sensitive not only to concentration but also to fiber length and pulp type. The mechanism responsible for the viscoelastic behavior in the range studied has been discussed, and it has been shown that the theories based on the statistical geometry of fiber structure are inadequate to explain our results, which may be better interpreted in the light of Rouse's theory for dilute solutions of macromolecules. © 1969.