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Cellulose




Cellulose
( C 6 H 10 O 5)n
is a long-chain Polymer ic Polysaccharide Carbohydrate , of Beta-glucose . It forms the primary structural component of green Plant s. The primary cell wall of green plants is made primarily of cellulose; the secondary wall contains cellulose with variable amounts of lignin. Lignin and cellulose, considered together, are termed Lignocellulose , which (as Wood ) is the most common Biopolymer on Earth .


HISTORY AND APPLICATIONS


Cellulose is a common material in plant Cell Wall s and was first noted as such in 1838 . It occurs naturally in almost pure form in Cotton fiber. In combination with Lignin and Hemicellulose , it is found in all plant material. Cellulose is the most abundant form of living terrestrial biomass .

Some animals, particularly Ruminant s and Termite s, can digest cellulose with the help of Symbiotic micro-organisms - see Methanogen . Cellulose is not Digestible by Human s, and is often referred to as 'dietary fibre' or 'roughage', acting as a hydrophilic bulking agent for Faeces .

Cellulose is the major constituent of Paper ; further processing can be performed to make Cellophane and Rayon , and more recently Modal , a textile derived from beechwood cellulose. Cellulose is used within the laboratory as a solid-state substrate for Thin Layer Chromatography , and Cotton Linter s, is used in the manufacture of Nitrocellulose , historically used in Smokeless Gunpowder .


CHEMISTRY


Cellulose 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 into a carbohydrate ''matrix'', helping keep plant cells rigid.

Given a cellulose material, the portion that does not dissolve in a 17.5% solution of sodium hydroxide at 20 °C is ''α cellulose'', which is true cellulose; the portion that dissolves and then precipitates upon acidification is ''β cellulose''; and the proportion that dissolves but does not precipitate is ''γ cellulose''.

Cellulose can be assayed using a method described by Updegraff in 1969 , where the fiber is dissolved in Acetic and Nitric Acid , and allowed to react with Anthrone in Sulfuric Acid . The resulting coloured compound is assayed spectrophotometrically at a wavelength of approximately 635 Nm .


DERIVATIVES


The Hydroxyl groups of cellulose can be partially or fully reacted with various chemicals to provide derivates with useful properties. Cellulose Esters and cellulose Ether s are the most important commercial materials. In principle, though not always in current industrial practice, cellulosic polymers are renewable resources.

Among the esters are Cellulose Acetate and Triacetate , which are film- and fiber-forming materials that find a variety of uses. The inorganic ester Nitrocellulose was initially used as an explosive and was an early film forming material.

Ether derivatives include
  • Ethylcellulose, a water-insoluble commercial thermoplastic used in coatings, inks, binders, and controlled-release drug tablets;

  • Hydroxypropyl Cellulose ;

  • Carboxymethyl Cellulose ;

  • Hydroxypropyl methyl cellulose, E464 , used as a viscosity modifier, gelling agent, foaming agent and binding agent;

  • Hydroxyethyl methyl cellulose, used in production of cellulose films.



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