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As is well known, most of the solvent systems have various deficiencies. However, Cellulose can hardly be dissolved in common solvents, due to its extensive intra- and intermolecular hydrogen bonding, and the amphiphilicity distribution of the crystal surfaces. Therefore the search for new efficient solvents to measure the molecular weight of cellulose has always been a research hotspot. There is another common copper (II) ethylenediamine (CED) method (GB/T 1548–2004), which can accurately measure the molecular weight of cellulose, but it is difficult to prepare CED solution. Although the test process of the Cuoxam method is simple and fast, cellulose degrades greatly in Cuoxam solution. The commonly-used method to measure the molecular weight of cellulose in the laboratory is the cuprammonium hydroxide (Cuoxam) method (GB/T 9170–1999). The premise of the methods is that cellulose is dissolved in the solvent without degradation. The static light scattering (SLS) method is also used for determination of the cellulose molecular weight. One is the GPC method, which usually conducted for cellulose derivatives.

There are three methods for determination of molecular weight of cellulose. The accurate determination of molecular weight is one of the key issues for the development of cellulose-based materials in laboratory research, as well as industry. The molecular weight (M) of cellulose affects the processing conditions, as well as the performance of the final cellulose products. Cellulose are widely used in our daily life and modern industrial production as renewable materials, composite materials, and cellulose derivatives.

The increasingly serious environmental and energy issues have prompted the development of natural polymer materials. A time efficient and reliable method has been supplied for determination of the degree of polymerization and the molecular weight of cellulose.Ĭellulose is the most abundant natural polymer in the Earth, which is widely produced by various plants, bacteria, and algae. The natural cellulose can be molecularly dispersed in the multiple-component solvent (THDS), and kept stable for a certain period. No considerate degradation was observed by comparing the intrinsic viscosity and the degree of polymerization (DP) values of the original with and the regenerated cellulose samples.

The reliability of the established Mark–Houwink equation was cross-checked by the gel permeation chromatography (GPC) and traditional copper (II) ethylenediamine (CED) method. The cellulose dispersion in the THDS was proved to be in molecular level by atomic force microscope (AFM) and dynamic light scattering (DLS). The value of 1.21 indicates that the cellulose molecules dissolve in THDS quite well. The relationship between the molecular weight of cellulose and the intrinsic viscosity tested in such dilute solutions has been established in the form of the Mark–Houwink equation, = 0.24 × DP 1.21. That is to say, the cellulose was dissolved in the solution in molecular level, and the viscosity of the solution is linearly dependent on the concentration of cellulose. In this work, tetra-n-butylammonium hydroxide (TBAH) and dimethyl sulfoxide (DMSO) aqueous solution (THDS) were used to dissolve cellulose in a few minutes under room temperature into true molecular solutions. The determination of molecular weight of natural cellulose remains a challenge nowadays, due to the difficulty in dissolving cellulose.