Cellulose properties focus on the remarkable characteristics of cellulose bio-molecule. Cellulose is considered the most important and available biomass compound in the world. A lot of derivatives, biochemicals, and materials are obtained after some chemical transformation from this biopolymer.
What is cellulose?
Cellulose is a natural biopolymer consisting of a linear structure. It contains anhydroglucose monomers. These glucose monomers are linked via β-(1–4) bonds. The molecular structure of cellulose is ((C6H10O5)n; where n is the degree of polymerization and n equals 10,000–5000, depending on the source used for cellulose extraction.
Cellulose definition
Cellulose is one type of polysaccharide and a crucial biopolymer on Earth. It is considered as the most important structural component of the primary cell wall of green plants. This biopolymer consists of a linear chain of several hundred to many thousands of β(1 → 4) linked d-glucose units which have the molecular formula ((C6H10O5)n; where n is the degree of polymerization.
What are the sources of cellulose?
The sources of cellulose are divided into two categories. They are natural and synthetic. The natural sources include seed fibers, leaf fibers, bast fibers, fruit fibers, and stalk fibers. The synthetic sources include cellulose derivatives, methylcellulose, ethyl cellulose, nitrocellulose, carboxymethyl cellulose, etc.
Cellulose sources
Cellulose can be obtained from seed fibers like cotton and kapok. cotton and kapok fiber contain 90% cellulose.
Cellulose can be obtained from leaf fibers like Sisal, fique, and agave. Sisal, fique, and agave fiber contain 33% cellulose.
Cellulose can be obtained from bast fibers like flax, jute, kenaf, Hemp, ramie, rattan, and vine fiber. flax, jute, kenaf, Hemp, ramie, rattan, and vine fiber contain 30% cellulose.
Cellulose can be obtained from fruit fibers like coir fibers. Coir fiber contains 30-50% cellulose.
Cellulose can be obtained from Stalk fibers like Rice, barley, wheat straws, bamboo, grass, and Tree wood fibers. Rice, barley, wheat straws, bamboo, grass, and tree wood fibers contain 40-50% cellulose.
What is the structure of cellulose?
Cellulose is an important biopolymeric compound containing ringed glucose molecules. The repeating units of this biomolecule consist of anyhydroglucose units (AGU). These units are joined together through an oxygen covalently bonded to the C1 of one glucose ring and the C4 of the adjoining ring (1 →4linkage). These are called β 1-4 glucosidic bonds. The molecular formula of cellulose molecule is (C6H10O5)n, where n varies between 10,000 and 15,000.
Cellulose structure
Cellulose structure comprises the linear combination of glucose monomers. Each repeating unit of glucose contains three hydroxyl groups. These hydroxyl groups have the ability to make hydrogen bonds between cellulose chains that govern the outstanding physical properties of cellulose molecules. The hydrogen bonding interchain exists between hydroxyl groups and oxygens of the adjoining ring molecules to stabilize the total linkage properly. As a result, the linear configuration of this biomolecule can be achieved.
The van der Waal forces and intermolecular hydrogen bonds between hydroxyl groups and oxygens of adjacent molecules lead to the formation of cellulose chain fibrils. The existence of intra- and inter-chain hydrogen bonding networks is responsible for making this biopolymer more stable. So, we get the high axial stiffness of this biopolymer. Cellulose fibrils show highly ordered crystalline structures and regions. They have lower amorphous regions and lead to more stable molecules. Due to the presence of this structural shape, cellulose properties are excellent.
History of Cellulose
This molecule was first synthesized by French Chemist Anselme Payen in 1838. He has also suggested the chemical formula of this biomolecule. In 1870, celluloid molecule was discovered by Hyatt Manufacturing Company. Rayon was synthesized from cellulose molecule in 1890 and Cellophane was synthesized from cellulose molecule in 1912. The structural formula of cellulose biomolecule was invented by Hermann Staudinger in 1920. It was possible to synthesize cellulose in 1992 without using any biological enzymes by Kobayashi and Shoda
What is cellulose fiber?
Cellulose fiber is a common fiber that is extracted from a cellulose source. It consists of a matrix of hemicelluloses attached to a lignin molecule. Cellulose fibers are called different names based on their sources like flax fibers, cotton fibers, bast fibers, etc.
Cellulose fibers
Cellulose fibers come from various natural sources like bamboo trees, papaya trees, beech trees, etc. They are also generated from various agricultural residues like sugarcane bagasse, rice straw, wheat straw, etc.
How cellulose is made?
Cellulose biopolymer is generally produced by the photosynthesis process. At first, carbon dioxide and water molecules convert into glucose molecules and oxygen after consuming energy from sunlight. These glucose molecules are linked together by glycosidic linkage and form cellulose molecule that gives proper shape and strength to plants. Due to the presence of this formulation, cellulose properties are remarkable.
What are the functions of cellulose?
Cellulose consists of hundreds to many thousands of β (1→4) linked D glucose units. It provides the proper strength, various types of cell division, and specific structure. It supports the plant cell walls and acts like a reinforcing bar. Having the presence of this structural shape, cellulose properties are notable.
Functions of Cellulose
This biopolymeric molecule gives the main structural shape of the plant cell walls. It provides the higher tensile strength in plants. It is the main factor to grow upright the plants as well as the cell division.
What are the cellulose properties?
Cellulose properties consist of biodegradability, biocompatibility, non-toxicity, and less hygroscopic in nature. It cannot dissolve into water and contains lower density. The tensile strength of this biomolecule is higher and white type crystalline powder.
Cellulose properties
Cellulose molecule is completely renewable and biodegradable containing lower density, high porosity, and a large specific surface area. The melting point of this biomolecule is 260-270oC with 1.5 gm/cm3 density. The molecular weight of this molecule is 162.1406 g/mol contains no odor, no color, and is biocompatible in nature.
Cellulose synthesis
Pure cellulose molecules can be synthesized from natural sources by following some steps. Firstly, the cellulosic fibers are kept in dirty water for 2 weeks. At this time, these fibers degrade properly in the presence of bacteria. Then the fibers can be extracted and treated with detergent to remove dirt. Then the fresh fibers should be treated with NaOH to separate the fibrous mass. Then the separated fibrous mass should be treated with hydrogen peroxide (H2O2) to remove coloring components.
After peroxide treatment, the bleached fibers must be treated with NaClO2 to remove the lignin. Then the fibers must be treated with 0.2% Na2S2O5 solution. Finally, the fibers should be treated with 17.5% NaOH solution to remove the hemicelluloses and washed properly to get the pure cellulose.
Cellulose derivatives
There are various cellulose derivates can be obtained from the cellulose biomolecule by applying some chemical process. Cellulose derivatives are classified into two categories namely cellulose ether derivatives and cellulose ester derivatives. The most common cellulose derivatives are hydroxypropyl cellulose, methylcellulose, cellulose acetate, nitrocellulose, and carboxymethyl cellulose (CMC).
Cellulose ether derivatives
There are various cellulose ether derivatives namely hydroxyethyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, etc. that contain higher molecular weight, special chemical structure and the proper distribution of the substituent groups. Cellulose ether derivatives are synthesized by replacing the hydrogen atoms of hydroxyl groups in the AGU (anhydroglucose units) of cellulose with alkyl or substituted alkyl groups. These derivatives have good viscosity in solution, excellent surface activity, thermoplastic film characteristics, and stability against biodegradation, and oxidation.
Cellulose ester derivatives
Cellulose ester derivatives like cellulose acetate, cellulose acetate phthalate, Cellulose acetate butyrate, Cellulose acetate trimelitate, and hydroxupropylmethyl cellulose phthalate can be obtained by some specific chemical processes. These derivatives have good film-forming characteristics.
What are the properties of cellulose derivatives?
Cellulose derivatives contain excellent properties like good physical aging, swelling behavior, sol-gel transition or gel point, rigidity, and rupture strength.
What is cellulose acetate?
It is a common cellulosic derivative that consists of hydroxyl groups partially or completely acetylated. This cellulose derivative is less hygroscopic in nature, a nontoxic, nonirritant, and biodegradable material. It can be synthesized by esterification or trans-esterification reaction process. The degree of substitution values ranges from 29.0% to 44.8% and can exist as mono-, di-, and triacetate. This biopolymer is used to make sunglass frames, filter media, cigarette filters, osmotic pump-type tablets, and microparticles for the controlled release of drugs.
What is methylcellulose?
It is a common cellulosic derivative that consists of an alkyl group and is hydrophilic in nature. It acts as the bulk-forming and stool-softening agent for the treatment of constipation. This derivative can be produced by reacting methyl chloride and alkali cellulose molecules at a definite temperature. The degree of substitution ranges from 27.58%–31.5% in this molecule. Methyl cellulose or MC is in pharmaceutical industries to prepare oral solid pharmaceutical formulations as a binder and as a good coating agent. Methyl cellulose or MC has the properties of a binder with good plastic flow and wetting ability.
What is carboxymethyl cellulose?
Carboxymethyl cellulose or CMC has carboxymethyl groups in the glucopyranose monomers. Carboxymethyl cellulose or CMC can be obtained by treating the cellulose molecule with alkylating reagents after activating the noncrystalline regions of cellulose molecules. Carboxymethyl cellulose or CMC is a flammable, nontoxic, biodegradable, and renewable polymer.
Carboxymethyl cellulose or CMC is used to prepare films, hydrogel, scaffolds, or nonwoven mats, suitable fillers in composites, food packaging, etc.
What is Nitrocellulose?
Nitrocellulose or cellulose nitrate is another cellulose derivative that was first synthesized in 1845 by Schonbein. It is highly flammable and can be synthesized by reacting the cellulose molecule with nitric acid in the presence of a sulfuric acid catalyst and water. Nitrocellulose or cellulose nitrate is used in defense industries to make modern gunpowder and in some lacquers and paints. Nitrocellulose or cellulose nitrate is also used to make jettison components of the rocket/space capsule, playing cards, filter media, table tennis balls, guitar sticks, and certain photographic films.
What are the differences between cellulose and hemicelluloses?
There exist various differences between cellulose and hemicelluloses which are written below:
Differences between cellulose and hemicelluloses on the basis of definition
Cellulose definition: It consists of Anhydro glucose units (AGU) attached by covalent bonds via bita 1,4-glycosidic linkages.
Hemicelluloses definition: It consists of a number of heteropolymers like arabinoxylans which are present along with cellulose in plant cell walls.
Differences between cellulose and hemicelluloses on the basis of structure
Cellulose: Cellulose is a straight-chain polymer consisting of 7,000–15,000 glucose monomers per polymer.
Hemicelluloses: A hemicellulose molecule is a branched polymer consisting of 500–3,000 glucose units.
Differences between cellulose and hemicelluloses on the basis of stability
Cellulose: Cellulose biomolecule consists of amorphous and crystalline regions. As a result, this biopolymer shows more stability.
Hemicelluloses: Hemicellulose molecule contains amorphous regions. As a result, the strength of this biomolecule is lower than cellulose biomolecule.
Differences between cellulose and hemicelluloses on the basis of subunits
Cellulose: Cellulose biomolecule contains D-Pyran glucose units.
Hemicelluloses: Hemicellulose molecule contains D-Xylose, mannose, L-arabinose, galactose, and glucuronic acid.
What are the differences between cellulose and lignin?
There exist various differences between cellulose and lignin which are written below:
Difference between cellulose and lignin on the basis of definition
Cellulose definition: It consists of hundreds to thousands of glucose units connected by glycosidic linkages.
Lignin definition: It is a cross-linked polymeric molecule having three monolignols, namely coniferyl alcohol, p-coumarylalcohol, and sinapyl alcohol.
Difference between cellulose and lignin on the basis of water absorption properties
Cellulose: Cellulose biomolecule has a hydrophilic character.
Lignin: Lignin biomolecule has a hydrophobic character.
Difference between cellulose and lignin on the basis of location
Cellulose: Cellulose biomolecule is found in the primary cell wall of plants.
Lignin: Lignin biomolecule is found in the secondary cell wall of plants.
Difference between cellulose and lignin on the basis of structure
Cellulose: Cellulose biomolecule contains a linear structure with linear β glucose subunits.
Lignin: Lignin biomolecule has three-dimensional structures.
Difference between cellulose and lignin on the basis of bonds
Cellulose: Cellulose biomolecule has hydrogen bonds or β 1-4 glycosidic.
Lignin: Lignin biomolecule has ester bonds or ether bonds.
What are the differences between cellulose and starch?
There are various differences between cellulose and starch which are written below:
Cellulose vs starch
Difference between cellulose and starch on the basis of definition
Cellulose definition: A cellulose biomolecule is a polysaccharide composed of β glucose monomers linked together by glycosidic linkages.
Starch definition: Starch biomolecule is a carbohydrate consisting of amylase, and amylopectin joined together by glycosidic linkages
Difference between cellulose and starch on the basis of glucose range
Cellulose: Cellulose biomolecule has 100-10,000 glucose subunits.
Starch: Starch biomolecule has 200-1000 glucose molecules.
Difference between cellulose and starch on the basis of function
Cellulose function: Cellulose biomolecule provides the structural shape and strength to plants.
Starch function: Starch biomolecule is considered the main carbohydrate storage in plants.
Difference between cellulose and starch on the basis of linkage
Cellulose linkage: Cellulose biomolecule has beta linkage.
Starch linkage: Starch biomolecule has alpha linkage.
Difference between cellulose and starch on the basis of chain type
Cellulose chain type: Cellulose biomolecule is a straight-chain polymer.
Lignin chain type: Starch biomolecule is a long and branched chain.
Why can’t humans digest cellulose while ruminants can?
Animals like cows, bulls, camels, sheep, and deer can digest cellulose due to the presence of appropriate enzymes (cellulase) to break down this polymeric molecule. Humans cannot digest cellulose molecules due to the absence of cellulase enzymes to break down this polymeric molecule.
What are the applications of cellulose?
Cellulose properties are remarkable in nature. So, Cellulose biopolymer is widely used in textile industries, pharmaceutical industries, food industries, paper industries, etc.
Cellulose applications in the food industry
Cellulose biopolymer is used in various food industries due to its attractive cellulose properties for the manufacture of foods. It can be used to make white bread, vegetarian burgers, chicken nuggets, low-fat ice cream, and various food items. It can also used in sauces to enhance its thickening and emulsifying actions. Cellulose molecule has the ability to absorb moisture and can be used in anti-caking application fields.
Cellulose applications in medical
Cellulose biopolymer is used in various medical fields due to its attractive cellulose properties to the proper treatment of renal failure during the failure of the human kidney. Cellulose is an important compound for wound dressing. Cellulose is used in tissue engineering sectors and controllable drug delivery systems.
Cellulose applications in textile industries
Cellulose biopolymer is used in various textile industries due to its attractive cellulose properties to make various fabrics. Cellulose biopolymer has the properties of adsorbing moisture and has the ability to remove the growth of bacteria.
Cellulose applications in paper industries
Cellulose biopolymer is used in various paper industries due to its attractive cellulose properties to make paper and paper-related products. Kraft pulp from cellulosic fibers is used to make paper after some processing.
Cellulose applications in pharmaceutical industries
Cellulose biopolymer is used in various pharmaceutical industries due to its attractive cellulose properties to make capsule coating and various types of drug delivery systems. It can be used as bioadhesives to prepare buccal, ocular, vaginal, nasal, and transdermal formulations.
References
Gupta, P. K., Raghunath, S. S., Prasanna, D. V., Venkat, P., Shree, V., Chithananthan, C., … & Geetha, K. (2019). An update on overview of cellulose, its structure and applications. Cellulose, 201(9), 84727.
Poletto, M., Pistor, V., &Zattera, A. J. (2013). Structural characteristics and thermal properties of native cellulose. Cellulose-fundamental aspects, 2, 45-68.
Lavanya, D. K. P. K., Kulkarni, P. K., Dixit, M., Raavi, P. K., & Krishna, L. N. V. (2011). Sources of cellulose and their applications—A review. International Journal of Drug Formulation and Research, 2(6), 19-38.
