Rheological behavior of cellulose/monohydrate of N-methylmorpholine N-oxide solutions. Part2 : Glass transition domain
Résumé
Dynamic mechanical experiments performed with original conditions allowed the analysis of a solution containing 15% cellulose dissolved in a monohydrate of N-methylmorpholine N-oxide (NMMO) in the amorphous state. The glass transition zone is studied by dynamic tensile experiments, while dynamic torsion technique is used to determine the viscoelastic behavior in the glassy state. A master curve of the storage and loss modulus versus frequency can be deduced from the isochronal curves measured by both techniques. This work allows one to complete the corresponding master curve obtained for the liquid state and presented in a previous work [Rheol. Acta 1998;37: 107]. The measurements below the glass transition temperature exhibit two secondary relaxations. A modeling of the overall viscoelastic behavior, using the Nowick and Berry approach and the quasi-point defect theory, is proposed. Physical parameters deduced from this modeling are then discussed