The degree of polymerization (DP) and the molecular weight distribution (MWD) play a special role in producin cellulose fiber by using the N-methyl morpholine N-oxide (NMMO) process. In this paper, rheologicall methods have been used to determine the MWD of cellulose. It is shown that the limiting compliance J_e~0 of cellulose samples increases strongly with the increasing broadness of MWD, and that the polydispersity index / of the distribution of relaxation times can also well characterize the polydispersity of MWD of the cellulose samples. By using Tuminello's method, the cumulative weight distribution C(M) can be calculated from the terminal modulus and the plateau modulus of the cellulose/NMMo solution via 1-G min(#omega#)/G_N~0 (G min(#omega# and G_N~0 are the storage modulus and the plateau modulus respectively).
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