History and Applications
Cellulose is the common material of plant cell walls and was first noted as such in 1838. It occurs naturally in almost pure form only in cotton fibre and in combination with lignin and any hemicellulose, it is found in all plant material - wood, leaves, stalks etc. Cellulose is the most abundant form of living terrestrial biomass (Crawford, R. L. 1981. Lignin biodegradation and transformation, John Wiley and Sons, New York.) Cellulose, especially cotton linters, is used in the manufacture of nitrocellulose, used historically in smokeless gunpowder.
Cellulose monomers (beta-glucose) are linked together through 1,4 glycosidic bonds. Cellulose is a straight chain--no coiling occurs. In microfibrils, the multiple hydroxide groups hydrogen bond with each other, holding the chains firmly together and contributing to their high tensile strength. This strength is important in cell walls, where they are meshed in to a carbohydrate matrix, which helps to keep plants rigid.
Given a cellulose material, the portion that does not dissolve in a 17.5% solution of sodium hydroxide at 20 deg C. is Alpha Cellulose, this is true cellulose; the portion that dissolves and then precipitates upon acidification is Beta Cellulose; and the proportion that dissolves but does not precipitate is called Gamma Cellulose.