Pulp cellulose , degree polymerization

Bleached cotton stalk pulp is treated with different concentrations of ethylene diamine (50-100%) for 20 min. It is clear that the crystallinity index (CrI) of these treated pulps is decreased by increasing the concentration of ethylene diamine that is, the decrystallization increases. The degree of polymerization is nearly the same, but some increase is shown in the sample treated with 100% ethylene diamine. This indicates that 100% ethylene diamine may act as a dissolving agent for low degree of polymerization (DP) of cellulosic chains and hemicellulose. 

The use of xylanases in the preparation of high-purity cellulosic materials requires that the enzyme preparations be free of any cellulase contamination. Treatments of pulps with xylanase preparations containing cellulases have resulted in damage to cellulose fibres as revealed by a drop in pulp viscosities (12,14,17). Similar pulp treatments in which cellulase-free xylanases were used resulted in increases in pulp viscosities (10,18,19). We have shown recently that an apparent increase in the degree of polymerization of cellulose treated with a cellulase-free xylanase is likely due to the selective removal of xylan, leaving an enriched cellulose residue (20). 

Highly purified cellulose wood pulp (greater than 95% alpha cellulose) is the basic raw material for making cellulose acetate. The natural polymer, cellulose, in wood pulp has a degree of polymerization of 500 to 1000, the basic repeating unit of which is cellubiose ... 

The condition of the cellulose fiber in a pulping operation is often followed by measuring the viscosity—degree of polymerization (DP) of the cellulose. In the present work, an increase in brittleness of the paper is the property of interest, and this will be followed by the change in folding endurance. Oxidation of the cellulose will show up by the increase in the carboxyl group. This will be estimated by the pH and titration values of the slurried fiber. 

The chain length of cellulose expressed in the number of AGU constituents (degree of polymerization, DP or n) varies with the origin and treatment of the raw material. In case of wood pulp, the values are typically between 300-1700. Cotton and other plant fibres have DP values in the 800-10000 range, depending on treatment. 

The terms a-, jS-, and y-cellulose are used slightly differently in the wood-pulp industry. Here, a-cellulose is the high-molecular-weight component. jS-cellulose is the fraction that is soluble in 17.5% alkali and that is precipitated by neutralization. y-Cellulose is the component that remains soluble during neutralization. Both P- and y-celluloses have low degrees of polymerization (200) and are partly oxidized. 

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