Cellulose - Wikipedia, The Free Encyclopedia 1v1iy

Cellulose From Wikipedia, the free encyclopedia

Cellulose is an organic compound with the formula (C6H10O5)n , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4) linked D-glucose units.[2][3]

Cellulose[1]

Cellulose is the structural component of the primary cell wall of green plants, many forms of algae and the oomycetes. Some species of bacteria secrete it to form biofilms. Cellulose is the most common organic compound on Earth. About 33% of all plant matter is cellulose (the cellulose content of cotton fiber is 90%, that of wood is 40–50% and that of dried hemp is approximately 75%).[4][5][6] For industrial use, cellulose today is mainly obtained from wood pulp and cotton. Cellulose is mainly used to produce paperboard and paper; to a smaller extent it is converted into a wide variety of derivative products such as cellophane and rayon. Converting cellulose from energy crops into biofuels such as cellulosic ethanol is under investigation as an alternative fuel source. Some animals, particularly ruminants and termites, can digest cellulose with the help of symbiotic micro-organisms that live in their guts. Humans can digest cellulose to some extent,[7][8] however it mainly acts as a hydrophilic bulking agent for feces and is often referred to as "dietary fiber".

Contents 1 History 2 Products 2.1 Cellulose source and energy crops 3 Structure and properties 4 Assaying a cellulose-containing material 5 Biosynthesis 6 Breakdown (cellulolysis) 7 Hemicellulose 8 Derivatives 9 References 10 External links

History

Identifiers CAS number

9004-34-6

UNII

SMD1X3XO9M

EC-number

232-674-9

ChEMBL

CHEMBL1201676 Properties

Molecular formula

(C6H10O5)n

Appearance

white powder

Density

1.5 g/cm3

Melting point

decomp.

Solubility in water

none Hazards

EU Index

not listed

NFPA 704

1

1

0

Related compounds Related compounds

Starch

() (what is: / ?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references

Cellulose was discovered in 1838 by the French chemist Anselme Payen, who isolated it from plant matter and determined its chemical formula.[2][9][10] Cellulose was used to produce the first successful thermoplastic polymer, celluloid, by Hyatt Manufacturing Company in 1870. Hermann Staudinger determined the polymer structure of cellulose in 1920. The compound was first chemically synthesized (without the use of any biologically derived enzymes) in 1992, by Kobayashi and Shoda.[11]

Products

See also: dissolving pulp and pulp (paper) The Kraft process is used to separate cellulose from lignin, another major component of plant matter. Cellulose is the major constituent of paper, paperboard, and card stock and of textiles made from cotton, linen, and other plant fibers. Cellulose can be converted into cellophane, a thin transparent film, and into rayon, an important fiber that has been used for textiles since the beginning of the 20th century. Both cellophane and rayon are known as "regenerated cellulose fibers"; they are identical to cellulose in chemical structure and are usually made from dissolving pulp via viscose. A more recent and environmentally friendly method to produce a form of rayon is the Lyocell process. Cellulose is the raw material in the manufacture of nitrocellulose (cellulose nitrate) which is used in smokeless gunpowder and as the base material for celluloid used for photographic and movie films until the mid 1930s. Cellulose is used to make water-soluble adhesives and binders such as methyl cellulose and carboxymethyl cellulose which are used in wallpaper paste. Microcrystalline cellulose (E460i) and powdered cellulose (E460ii) are used as inactive fillers in tablets[12] and as thickeners and stabilizers in processed foods. Cellulose powder is for example used in Kraft's Parmesan cheese to prevent caking inside the tube.

Cellulose in a plant cell.

Cotton fibres represent the purest natural form of cellulose, containing more than 90% of this carbohydrate.

Cellulose is used in the laboratory as the stationary phase for thin layer chromatography. Cellulose fibers are also used in liquid filtration, sometimes in combination with diatomaceous earth or other filtration media, to create a filter bed of inert material. Cellulose is further used to make hydrophilic and highly absorbent sponges.

Cellulose insulation made from recycled paper is becoming popular as an environmentally preferable material for building insulation. It can be treated with boric acid as a fire retardant. Cellulose consists of crystalline and amorphous regions. By treating it with strong acid, the amorphous regions can be broken up, thereby producing nanocrystalline cellulose, a novel material with many desirable properties.[13] Recently, nanocrystalline cellulose was used as the filler phase in bio-based polymer matrices to produce nanocomposites with superior thermal and mechanical properties. [14]

Cellulose source and energy crops Main article: Energy crop The major combustible component of non-food energy crops is cellulose, with lignin second. Non-food energy crops are more efficient than edible energy crops (which have a large starch component), but still compete with food crops for agricultural land and water resources.[15] Typical non-food energy crops include industrial hemp (though outlawed in some countries), switchgrass, Miscanthus, Salix (willow), and Populus (poplar) species. Some bacteria can convert cellulose into ethanol which can then be used as a fuel; see cellulosic ethanol.

Structure and properties Cellulose has no taste, is odorless, is hydrophilic with the angle of 20–30,[16] is insoluble in water and most organic solvents, is chiral and is biodegradable. It can be broken down chemically into its glucose units by treating it with concentrated acids at high temperature. Cellulose is derived from D-glucose units, which condense through β(1→4)-glycosidic bonds. This linkage motif contrasts with that for α(1→4)-glycosidic bonds present in starch, glycogen, and other carbohydrates. Cellulose is a straight chain polymer: unlike starch, no coiling or branching occurs, and the molecule adopts an extended and rather stiff rod-like

polymer: unlike starch, no coiling or branching occurs, and the molecule adopts an extended and rather stiff rod-like conformation, aided by the equatorial conformation of the glucose residues. The multiple hydroxyl groups on the glucose from one chain form hydrogen bonds with oxygen atoms on the same or on a neighbor chain, holding the chains firmly together side-by-side and forming microfibrils with high tensile strength. This strength is important in cell walls, where the microfibrils are meshed into a carbohydrate matrix, conferring rigidity to plant cells. Compared to starch, cellulose is also much more crystalline. Whereas starch undergoes a crystalline to amorphous transition when heated beyond 60–70 °C in water (as in cooking), cellulose requires a temperature of 320 °C and pressure of 25 MPa to become amorphous in water.[17] Several different crystalline structures of cellulose are known, corresponding to the location of hydrogen bonds between and within strands. Natural cellulose is cellulose I, with structures Iα and Iβ. Cellulose produced by bacteria and algae is enriched in Iα while cellulose of higher plants consists mainly of Iβ. Cellulose in regenerated cellulose fibers is cellulose II. The conversion of cellulose I to cellulose II is irreversible, suggesting that cellulose I is metastable and cellulose II is stable. With various chemical treatments it is possible to produce the structures cellulose III and cellulose IV.[18] Many properties of cellulose depend on its chain length or degree of polymerization, the number of glucose units that make up one polymer molecule. Cellulose from wood pulp has typical chain lengths between 300 and 1700 units; cotton and other plant fibers as well as bacterial cellulose have chain lengths ranging from 800 to 10,000 units.[11] Molecules with very small chain length resulting from the breakdown of cellulose are known as cellodextrins; in contrast to long-chain cellulose, cellodextrins are typically soluble in water and organic solvents. Plant-derived cellulose is usually found in a mixture with hemicellulose, lignin, pectin and other substances, while microbial cellulose is quite pure, has a much higher water content, and consists of long chains. Cellulose is soluble in cupriethylenediamine (CED), ciumethylenediamine (Cadoxen), N-methylmorpholine N-oxide and lithium chloride / dimethylformamide.[19] This is used in the production of regenerated celluloses (such as viscose and cellophane) from dissolving pulp.

A strand of cellulose (conformation Iα), showing the hydrogen bonds (dashed) within and between cellulose molecules.

A triple strand of cellulose showing the hydrogen bonds (cyan lines) between glucose strands

Assaying a cellulose-containing material Given a cellulose-containing material, the carbohydrate portion that does not dissolve in a 17.5% solution of sodium hydroxide at 20 °C is α cellulose, which is true cellulose. Acidification of the extract precipitates β cellulose. The portion that dissolves in base but does not precipitate with acid 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 to remove lignin, hemicellulose, and xylosans. The resulting cellulose is allowed to react with anthrone in sulfuric acid. The resulting coloured compound is assayed spectrophotometrically at a wavelength of approximately 635 nm. In addition, cellulose is represented by the difference between acid detergent fiber (ADF) and acid detergent lignin (ADL).

Biosynthesis In vascular plants cellulose is synthesized at the plasma membrane by rosette terminal complexes (RTCs). The RTCs are hexameric protein structures, approximately 25 nm in diameter, that contain the cellulose synthase enzymes that synthesise the individual cellulose chains.[20] Each RTC floats in the cell's plasma membrane and "spins" a microfibril into the cell wall.

RTCs contain at least three different cellulose synthases, encoded by CesA genes, in an unknown stoichiometry.[21] Separate sets of CesA genes are involved in primary and secondary cell wall biosynthesis. Cellulose synthesis requires chain initiation and elongation, and the two processes are separate. CesA glucosyltransferase initiates cellulose polymerization using a steroid primer, sitosterolbeta-glucoside, and UDP-glucose.[22] Cellulose synthase utilizes UDP-Dglucose precursors to elongate the growing cellulose chain. A cellulase may function to cleave the primer from the mature chain. Cellulose is also synthesised by animals, particularly in the tests of ascidians (where the cellulose was historically termed "tunicine") although it is also a minor component of mammalian connective tissue.[23]

Breakdown (cellulolysis)

Location and arrangement of cellulose microfibrils in the plant cell wall

Cellulolysis is the process of breaking down cellulose into smaller polysaccharides called cellodextrins or completely into glucose units; this is a hydrolysis reaction. Because cellulose molecules bind strongly to each other, cellulolysis is relatively difficult compared to the breakdown of other polysaccharides.[24] Processes do exist however for the breakdown of cellulose such as the Lyocell process [25] which uses a combination of heated water and acetone to break down the cellulose strands. Most mammals have only very limited ability to digest dietary fibres such as cellulose. Some ruminants like cows and sheep contain certain symbiotic anaerobic bacteria (like Cellulomonas) in the flora of the rumen, and these bacteria produce enzymes called cellulases that help the microorganism to break down cellulose; the breakdown products are then used by the bacteria for proliferation. The bacterial mass is later digested by the ruminant in its digestive system (stomach and small intestine). Similarly, lower termites contain in their hindguts certain flagellate protozoa which produce such enzymes; higher termites contain bacteria for the job. Some termites may also produce cellulase of their own.[26] Fungi, which in nature are responsible for recycling of nutrients, are also able to break down cellulose. The enzymes utilized to cleave the glycosidic linkage in cellulose are glycoside hydrolases including endo-acting cellulases and exo-acting glucosidases. Such enzymes are usually secreted as part of multienzyme complexes that may include dockerins and carbohydrate-binding modules.[27]

Hemicellulose Main article: Hemicellulose Hemicellulose is a polysaccharide related to cellulose that comprises about 20% of the biomass of most plants. In contrast to cellulose, hemicellulose is derived from several sugars in addition to glucose, especially xylose but also including mannose, galactose, rhamnose, and arabinose. Hemicellulose consists of shorter chains – around 200 sugar units. Furthermore, hemicellulose is branched, whereas cellulose is unbranched.

Derivatives The hydroxyl groups (-OH) of cellulose can be partially or fully reacted with various reagents to afford derivatives with useful properties like mainly cellulose esters and cellulose ethers (-OR). In principle, though not always in current industrial practice, cellulosic polymers are renewable resources. Ester derivatives include:

Cellulose ester Organic esters

Inorganic esters

Reagent Organic acids

Inorganic acids

Example

Reagent

Group R

Cellulose acetate

Acetic acid and acetic anhydride

H or -(C=O)CH3

Cellulose triacetate

Acetic acid and acetic anhydride

-(C=O)CH3

Cellulose propionate

Propanoic acid

H or -(C=O)CH2CH3

Cellulose acetate propionate

Acetic acid and propanoic acid

H or -(C=O)CH3 or (C=O)CH2CH3

Cellulose acetate butyrate

Acetic acid and butyric acid

H or -(C=O)CH3 or (C=O)CH2CH2CH3

Nitrocellulose (cellulose nitrate)

Nitric acid or another powerful nitrating agent

H or -NO2

Cellulose sulfate

Sulfuric acid or another powerful sulfuring agent

H or -SO3H

The cellulose acetate and cellulose triacetate are film- and fiber-forming materials that find a variety of uses. The nitrocellulose was initially used as an explosive and was an early film forming material. With camphor, nitrocellulose gives celluloid. Ether derivatives include:

Cellulose ethers Alkyl

Reagent

Example

Reagent

Group R = H or

Halogenoalkanes Methylcellulose Chloromethane -CH3

Hydroxyalkyl Epoxides

Water E Application solubility number Cold water soluble

E461

Ethylcellulose

Chloroethane

-CH2CH3

A commercial thermoplastic used in Water coatings, inks, E462 insoluble binders, and controlledrelease drug tablets

Ethyl methyl cellulose

Chloromethane -CH3 or and CH2CH3 chloroethane

E465

Hydroxyethyl cellulose

Ethylene oxide -CH2CH2OH

Hydroxypropyl Propylene cellulose oxide (HPC) Hydroxyethyl methyl cellulose

Cold/hot Gelling and water thickening soluble agent

Cold water CH2CH(OH)CH3 soluble

Chloromethane -CH3 or and ethylene CH2CH2OH oxide

Cold water soluble

Hydroxypropyl Chloromethane Cold -CH3 or methyl and propylene water cellulose CH2CH(OH)CH3 oxide soluble (HPMC) Ethyl hydroxyethyl cellulose

Chloroethane and ethylene oxide

Carboxymethyl Halogenated Chloroacetic Carboxyalkyl cellulose carboxylic acids acid (CMC)

E463 Production of cellulose films Viscosity modifier, gelling, E464 foaming and binding agent

-CH2CH3 or— CH2CH2OH

-CH2COOH

E467 Often used as its sodium salt, Cold/Hot sodium water E466 carboxymethyl soluble cellulose (NaCMC)

The sodium carboxymethyl cellulose can be cross-linked to give the croscarmellose sodium (E468) for use as a disintegrant in pharmaceutical formulations.

References 1. ^ Nishiyama, Yoshiharu; Langan, Paul; Chanzy, Henri (2002). "Crystal Structure and Hydrogen-Bonding System in Cellulose Iβ from Synchrotron X-ray and Neutron Fiber Diffraction". J. Am. Chem. Soc 124 (31): 9074–82. doi:10.1021/ja0257319 (http://dx.doi.org/10.1021%2Fja0257319) . PMID 12149011 (//www.ncbi.nlm.nih.gov/pubmed/12149011) ..

2. ^ a b Crawford, R. L. (1981). Lignin biodegradation and transformation. New York: John Wiley and Sons. ISBN 0-47105743-6. 3. ^ Updegraff DM (1969). "Semimicro determination of cellulose in biological materials". Analytical Biochemistry 32 (3): 420–424. doi:10.1016/S0003-2697(69)80009-6 (http://dx.doi.org/10.1016%2FS0003-2697%2869%2980009-6) . PMID 5361396 (//www.ncbi.nlm.nih.gov/pubmed/5361396) . 4. ^ Cellulose. (2008). In Encyclopædia Britannica. Retrieved January 11, 2008, from Encyclopædia Britannica Online. 5. ^ Chemical Composition of Wood (http://www.ipst.gatech.edu/faculty/ragauskas_art/technical_reviews/Chemical%20Overview%20of%20Wood.pdf) 6. ^ G. Buschle-Diller, C. Fanter, F. Loth (April 1999). "Structural changes in hemp fibers as a result of enzymatic hydrolysis with mixed enzyme systems" (http://www.globalhemp.com/1999/04/structural-changes-in-hemp-fibers-as-aresult-of-enzymatic-hydrolysis-with-mixed-enzyme-systems.html) . Textile Research Journal 69 (4): 244-251. http://www.globalhemp.com/1999/04/structural-changes-in-hemp-fibers-as-a-result-of-enzymatic-hydrolysis-with-mixedenzyme-systems.html. 7. ^ Slavin, JL; Brauer, PM; Marlett, JA (1981). "Neutral detergent fiber, hemicellulose and cellulose digestibility in human subjects.". The Journal of Nutrition 111 (2): 287–97. PMID 6257867 (//www.ncbi.nlm.nih.gov/pubmed/6257867) . 8. ^ Joshi, S; Agte, V (1995). "Digestibility of dietary fiber components in vegetarian men.". Plant foods for human nutrition (Dordrecht, Netherlands) 48 (1): 39–44. doi:10.1007/BF01089198 (http://dx.doi.org/10.1007%2FBF01089198) . PMID 8719737 (//www.ncbi.nlm.nih.gov/pubmed/8719737) . 9. ^ A. Payen (1838) "Mémoire sur la composition du tissu propre des plantes et du ligneux" (Memoir on the composition of the tissue of plants and of woody [material]), Comptes rendus, vol. 7, pages 1052-1056. Payen added appendices to this paper on December 24, 1838 (see: Comptes rendus, vol. 8, page 169 (1839)) and on February 4, 1839 (see: Comptes rendus, vol. 9, page 149 (1839)). A committee of the French Academy of Sciences reviewed Payen's findings in : JeanBaptiste Dumas (1839) "Rapport sur un mémoire de M. Payen, relatif à la composition de la matière ligneuse" (Report on a memoir of Mr. Payen, regarding the composition of woody matter), Comptes rendus, vol. 8, pages 51-53. In this report, the word "cellulose" is coined and author points out the similarity between the empirical formula of cellulose and that of "dextrine" (starch). The above articles are reprinted in: Brongniart and Guillemin, eds., Annales des sciences naturelles ..., 2nd series, vol. 11 (Paris, : Crochard et Cie., 1839), pages 21-31 (http://books.google.com/books? id=VDRsFWwgUo4C&pg=PA21&lpg=PA21#v=onepage&q&f=false) . 10. ^ Young, Raymond (1986). Cellulose structure modification and hydrolysis. New York: Wiley. ISBN 0-471-82761-4. 11. ^ a b Klemm, Dieter; Brigitte Heublein, Hans-Peter Fink, Andreas Bohn (2005). "Cellulose: Fascinating Biopolymer and Sustainable Raw Material". ChemInform 36 (36). doi:10.1002/chin.200536238 (http://dx.doi.org/10.1002%2Fchin.200536238) . 12. ^ Weiner, Myra L.; Lois A. Kotkoskie (2000). Excipient Toxicity and Safety. New York ; Dekker. p. 210. ISBN 0-82478210-0. 13. ^ Peng, B. L., Dhar, N., Liu, H. L. and Tam, K. C. (2011). "Chemistry and applications of nanocrystalline cellulose and its derivatives: A nanotechnology perspective." (http://www.arboranano.ca/pdfs/Chemistry%20and%20applications%20of%20nanocrystalline%20cellulose%20and%20its %20derivatives%20A%20nanotechnology%20perspective-2011.pdf) . The Canadian Journal of Chemical Engineering 89 (5): 1191–1206. http://www.arboranano.ca/pdfs/Chemistry%20and%20applications%20of%20nanocrystalline%20cellulose%20and%20its %20derivatives%20A%20nanotechnology%20perspective-2011.pdf. 14. ^ Lawrence Pranger and Rina Tannenbaum "Biobased nanocomposites prepared by in situ polymerization of furfuryl alcohol with cellulose whiskers or montmorillonite clay" Macromolecules 41 (2008) 8682. http://dx.doi.org/10.1021/ma8020213 15. ^ Holt-Gimenez, Eric 2007. Biofuels: Myths of the Agrofuels Transition. Backgrounder. Institute for Food and Development Policy, Oakland, CA. 13:2 16. ^ Charles A. Bishop, ed. (2007). Vacuum deposition onto webs, films, and foils, Volume 0, Issue 8155 (http://books.google.com/books?id=vP9E3z7o6iIC&pg=PA165) . p. 165. ISBN 0-8155-1535-9. http://books.google.com/books?id=vP9E3z7o6iIC&pg=PA165. 17. ^ Deguchi, Shigeru; Tsujii, Kaoru; Horikoshi, Koki (2006). "Cooking cellulose in hot and compressed water". Chemical Communications (31): 3293. doi:10.1039/b605812d (http://dx.doi.org/10.1039%2Fb605812d) . 18. ^ Structure and morphology of cellulose (http://www.cermav.cnrs.fr/glyco3d/lessons/cellulose/index.html) by Serge Pérez and William Mackie, CERMAV-CNRS, 2001. Chapter IV. 19. ^ Stenius, Per (2000). "1". Forest Products Chemistry. Papermaking Science and Technology. 3. Finland: Fapet OY. p. 35. ISBN 952-5216-03-9. 20. ^ Kimura, S; Laosinchai, W; Itoh, T; Cui, X; Linder, CR; Brown Jr, RM (1999). "Immunogold labeling of rosette terminal cellulose-synthesizing complexes in the vascular plant vigna angularis" (//www.ncbi.nlm.nih.gov/pmc/articles/PMC144118/) . The Plant cell 11 (11): 2075–86. doi:10.2307/3871010 (http://dx.doi.org/10.2307%2F3871010) . JSTOR 3871010 (http://www.jstor.org/stable/3871010) . PMC 144118 (//www.ncbi.nlm.nih.gov/pmc/articles/PMC144118) . PMID 10559435 (//www.ncbi.nlm.nih.gov/pubmed/10559435) . //www.ncbi.nlm.nih.gov/pmc/articles/PMC144118/.

21. ^ Taylor, N. G. (2003). "Interactions among three distinct CesA proteins essential for cellulose synthesis". Proceedings of the National Academy of Sciences 100 (3): 1450. doi:10.1073/pnas.0337628100 (http://dx.doi.org/10.1073%2Fpnas.0337628100) . 22. ^ Peng, L; Kawagoe, Y; Hogan, P; Delmer, D (2002). "Sitosterol-beta-glucoside as primer for cellulose synthesis in plants". Science 295 (5552): 147–50. doi:10.1126/science.1064281 (http://dx.doi.org/10.1126%2Fscience.1064281) . PMID 11778054 (//www.ncbi.nlm.nih.gov/pubmed/11778054) . 23. ^ Endean, The Test of the Ascidian, Phallusia mammillata (http://jcs.biologists.org/content/s3-102/57/107.full.pdf) , Quarterly Journal of Microscopical Science, Vol. 102, part 1, pp. 107-117, 1961. 24. ^ David G. Barkalow, Roy L. Whistler, "Cellulose", in AccessScience, McGraw-Hill, doi:10.1036/1097-8542.118200 (http://dx.doi.org/10.1036%2F1097-8542.118200) . Retrieved 11 January 2008. 25. ^ H.Lyocell, "Cellulose" Issue 41, pp 419 26. ^ Tokuda, G; Watanabe, H (22 June 2007). "Hidden cellulases in termites: revision of an old hypothesis" (http://rsbl.royalsocietypublishing.org/content/3/3/336.long) . Biology Letters 3 (3): 336–339. doi:10.1098/rsbl.2007.0073 (http://dx.doi.org/10.1098%2Frsbl.2007.0073) . PMC 2464699 (//www.ncbi.nlm.nih.gov/pmc/articles/PMC2464699) . PMID 17374589 (//www.ncbi.nlm.nih.gov/pubmed/17374589) . http://rsbl.royalsocietypublishing.org/content/3/3/336.long 27. ^ Brás, Natércia; N. M. F. S. A. Cerqueira, P. A. Fernandes, M. J. Ramos (2008). "Carbohydrate Binding Modules from family 11: Understanding the binding mode of polysaccharides". International Journal of Quantum Chemistry 108 (11): 2030–2040. doi:10.1002/qua.21755 (http://dx.doi.org/10.1002%2Fqua.21755) .

External links Structure and morphology of cellulose (http://www.cermav.cnrs.fr/glyco3d/lessons/cellulose/index.html) by Serge Pérez and William Mackie, CERMAV-CNRS Cellulose (http://www.lsbu.ac.uk/water/hycel.html) , by Martin Chaplin, London South Bank University Clear description of a cellulose assay method (http://msa.ars.usda.gov/la/srrc/fb/ca.html) at the Cotton Fiber Biosciences unit of the USDA. Cellulose films could provide flapping wings and cheap artificial muscles for robots (http://www.technologyreview.com/read_article.aspx?ch=infotech&sc=&id=17127&pg=1) TechnologyReview.com Using cellulase enzymes in the bioethanol process (http://www1.eere.energy.gov/biomass/cellulase_enzyme.html) A list of cellulolytic bacteria (http://www.wzw.tum.de/mbiotec/cellmo.htm) Retrieved from "http://en.wikipedia.org/w/index.php?title=Cellulose&oldid=527955593" Categories: Cellulose Excipients Papermaking Polysaccharides

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