Importance of Cellulose: The commercial importance, significance and use of cellulose cannot be over emphasized. This is because cellulose has found use in several industrial raw materials, food components and household items. For instance, Cellulose provides the raw material for the production of paper, cellophane, celluloid and rayon including various types of plastics. Derivatives of cellulose such as cellulose nitrate are used in the manufacture of films, lacquers and explosives. Cellulose is almost pure cotton which requires very little treatment before being used in the manufacture of fabrics and other useful materials.
Wood pulp which is also a form of cellulose is mainly gotten from spruce. The first stage involved in the preparation of cellulose involves the removal of the lignin and other non-cellulose materials. This is done by treating the wood pulp in high temperature and pressure with sulphur(iv)oxide and calcium bisulphite. The purified pulp that comes out of this process which contains up to 97% pure cellulose is then dissolved and the cellulose generated as synthetic fibres or sheets. The regenerated cellulose has enormous tensile strength as well as several protective properties. This makes cellophane very ideal for wrapping purposes while rayon an even stronger material is used in the manufacture of industrial belts and tyre cords.
Chemical and Molecular Description of Cellulose
Cellulose is a material of immense structural significance. It is found in plant cell wall where it is very significant in maintaining the plant rigidity, water and material intake. Cellulose is a polysaccharide consisting of long chains of beta glucose molecules that are linked by glycosidic bonds. The orientation of the sugar molecules is such that the OH groups stick outwards from the chain in all directions. These OH groups can form hydrogen bonds with neighboring chains, thereby establishing a kind of three-dimensional lattice structure which is quite different from the way starch molecules are built-up.
Starch consists of a long chain of glucose molecules but the chain is coiled into a helix and the orientation of the glucose sub-units is such that most of the OH groups capable of forming hydrogen bonds project inwards. This means that there are no cross-linkages in starch and this is the very reason why it lacks the structural properties possessed by cellulose.
A single cellulose chain may contain as much as 10,000 sugar units with a total length of 5micrometer. The strength of the glycosidic bonds, together with the cross-links between the adjacent chains, makes cellulose tough just like rubber. In the cell wall, groups of about 2,000 cellulose chains are massed together to form ribbon-like microfibrils each between 10 and 30nm in diameter.