Differences in molecular properties of celluloses from different biological origins were investigated chiefly in terms of the rheological properties of their solutions in 8 wt % LiCl/N,N-dimethylacetamide (DMAc). Cotton unter (CC) and dissolving pulp (DP) were used as cellulose samples derived from plant, and a cellulose from Acelobacter xylimm was also used as a bacterial cellulose (BC). For the three kinds of cellulose solutions, the values of η0 - ηs (η0: zero shear rate viscosity of solution, ηs: solvent viscosity) were in proportion to the weight fraction of polymer. Φw in the dilute region. On the other hand, they were in proportion to Φw 4 for the CC and the DP solutions and ΦW3 for the BC solution in the semidilute or concentrated region. This Φ w-dependence of η0 - ηs shows that CC and DP, celluloses from plants, behave as a flexible polymer and that BC behaves as a rodlike polymer, according to several molecular theories. Plateau modulus, GN, was in proportion to Φw2 for the CC solution, signifying that network structure by entanglement was formed in the CC solution, as is often observed for solutions of flexible synthetic polymers. On the other hand, the concentrated solution of BC showed the typical small-angle X-ray scattering (SAXS) profile of two-phase systems, which can be well approximated by Debye-Bueche equation. This fact indicates that the structure of the BC solution apparently differs from the network structure.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering