| In this thesis, the development and basic feature of cellulose carbon fiber and its precursor have been briefly introduced. It is reviewed for the structure and properties of cellulose and the preparing processes about high performance cellulose fiber. In order to make high performance Lyocell, a study on dissolution of the cellulose withhigh molecular weight (DP>1000) in NMMO. H2O (N-methylmorpholine-N-oxidemonohydrate) and the Theological properties of high Mw cellulose/ NMMO. H2O solution have been carried out. The influence of the celluloses with different high Mw, which used as the raw materials for spinning, and the dissolving conditions on the spinnability and mechanical performance of Lyocell fibers are investigated. The characters of structure and properties of the Lyocell from high Mw cellulose are also discussed. Using NFUCl as a modifier to produce high strength Lyocell has beenstudied in detail when middle Mw cellulose pulp (DP 818, slightly higher thancommon cellulose pulp DP -600) used as a spinning material. Finally, we also discussed the structure and properties between viscose precursor for carbon fiber and Lyocell, a new precursor for carbon fiber, and compared two kinds of carbon fibers from rayon and Lyocell. In addition, a preliminary characterization on surface properties of rayon-based and Lyocell-based carbon fibers has finished by inverse gas chromatography.The investigation on dissolution of celluloses with high Mw shows that it isdisagreed with low Mw cellulose (DP 500-700), the dispersing step can be hardly observed under polar microscopy with a hot stage for high Mw cellulose during dissolving in NMMO.H2O. And the dissolving rate in NMMO.H2O and Theologicalproperties of high Mw cellulose/ NMMO.H2O solution strongly dependence on temperature. For cellulose/ NMMO. H2O solution, the higher the average degree of polymerization of cellulose, the higher the viscosity and the viscose flow active energy, lower the critical shearing rate, and the more notable the pseudoplasticity. Comparing with the results form visco-elasticity and GPC experiments shows that with the increase of cellulose Mw, the cross point of dynamic moduli (G', G'') master curves moves to low frequency direction for cellulose dope, and the moduli and frequency at the cross point are related to the appeared Mw and Mw distribution of cellulose in the solution, respectively.Results from spinning of high Mw cellulose dope and testing of Lyocell fibers show that it is one of potent approaches to making high performance Lyocell for using the high given Mw cellulose as a raw material to spin. The influence of process parameters on the mechanical properties of the Lyocell fibers spun from high Mw cellulose presents some differences to that spun from low Mw cellulose dope. In addition, the comparing experiment shows the origin, type, and the pretreatment of cellulose greatly affect the dissolving property and spinnability. Another discover is that adding a few o comparatively lower Mw pulp into those high Mw pulp can improve spinnability of the cellulose dope.The study of morphological and structure indicates that, as common Lyocell, those from high Mw cellulose, has also a round cross-section and smooth surface, and the skin-core structure can hardly be observed. The crystallinity and average orientation degree of Lyocell form high Mw cellulose is also higher than those from lower Mw cellulose, but the crystallites are longer under the same spinning conditions. The information from DMTA hints that amorphous of cellulose is not isotropic with a homophase, but a complex hemephase continuous structure, and hydrogen bonds in amorphous of the Lyocell with high Mw is stronger than in those of the Lyocell with low Mw. Analysis of related data can find the moduli and tenacity of the Lyocell with high Mw show good liner relationship with the logarithm of the product among the birefringence, mean degree of polymerization, and the orientation factors in crystaland amorphous zone , respectively.Not only can...
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