Cta2, Cellulose Acetate

به نام خدا

استات سلولز

استاد دکتر قاسميانRouzbeh Asadi Khansari

روزبه اسدی خوانساری

• جايگزيني هيدركسيل• استات سلولز محلول در كلروفرم• استات سلولز محلول در استن• استات سلولز و بخار نيترومتان• 1963كشف كريستالهاي منفرد پليمري در سال • كريستالهاي منفرد چهارگوش در ميكروسكوپ الكتروني• مرتب شدن بسته هاي موازي زنجيرودرانتها اتصال

زنجيرغيرموازي• درجه بلورين• XRD ترين استفاده در شناسايي تركيبات كريستالين گسترده

Properties of natural & synthetic fibers

Cellulose

Reaction of the OH group: esters, ethers, etc.

DS=degree of substitution is important: DS=0-3/glucoseThe DS is dependent on the availability of OH groups so it is a function of the H-bonding in cellulose!

Reaction of Cellulose Acetate

Esters commercially made by Eastman.Mostly short fibers for non-wovens like cigarette butts!

Relies on acetylated OH groups

-CC

O-

= O

cellulose + acetic acid + acetic anhydride + H2SO4

partial

hydrolysisdissolve in acetone and spin fiber

Cellulose will react under anhydrous conditions in the presence of acid catalyst and acetic anhydride to form cellulose tri-acetate. Cellulose acetate is the partially acetylated product of high purity cellulose and acetic anhydride. It is obtained by acid catalyzed hydrolysis of the tri-acetate to a DSav~2.4 (cellulose tri-acetate would be DS~3.0)

ester linkages!

Cellulose Acetate

CH3 C

O

OCOCH3

CH3 C

OH

OCOCH3

CH3 C

O

OCOCH3

+H + Cell

CH3 C

OH

OCOCH3

CH3 C

O

O

HO Cell

Cell

DS of Cellulose Acetate

H2SO4

C-OH + (CH3CO)2OOH group on

celluloseacetic anhydride

C-OOCCH3 + CH3COOHcellulose tri-

acetate=esteracetic acid (H from

cellulose OH)

acetic anhydride is split in 1/2

hydrolysisC-OOCCH3

cellulose tri-acetate=ester

+ 0.2H2O

C-(OOCCH3)0.8

cellulose acetate=ester

(OH)0.2

+ 0.2CH3COOHacetic acid

DS=3(0.8)=2.4/glucose can be v. high!

This material is soluble in acetone and other organic solventsProperties, like biodegradability, are f(DS): remember, the biggest impediment to this rxn is the availability of OH’s from H-bonding

this is fully acetylated cellulose

(sulfuric acid)

Degree of polymerization

History of Cellulose acetate(zyl, zylonite, Cellon and Rhodoid)

• Paul Schützenberger discovered cellulose acetate in 1865• George Miles more solvents in 1904 • Camille and Henri Dreyfus in 1910 • DOPE• In1914,The British Cellulose and Chemical Manufacturing Co - 1918 to

British Celanese Ltd• In 1918 The American Cellulose & Chemical Manufacturing Company in

New York by the Dreyfus brothers In 1927- the Celanese Corporation of America

• Mazzucchelli ,Celluloid Acetate sheets and Cellulose Nitrate • Cellulose acetate film was introduced in 1934• IBM in 1952 for use on their IBM 726 tape drive in the IBM 701 computer

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Fiber properties• Hand: soft, smooth, dry, crisp, resilient • Comfort: breathes, wicks, dries quickly, no static cling • Drape: linings move with the body linings conform to the garment • Color: deep brilliant shades with atmospheric dyeing meet colorfastness

requirements • Luster: light reflection creates a signature appearance • Performance: colorfast to perspiration staining, colorfast to dry cleaning, air and

vapor permeable • Tenacity: weak fiber with breaking tenacity of 1.2 to 1.4 g/d; rapidly loses strength

when wet; must be dry cleaned• Abrasion: poor resistance • Heat retention: poor thermal retention; no allergenic potential (hypoallergenic) • Dyeability: (two methods) cross-dying method where yarns of one fiber and those

of another fiber are woven into a fabric in a desired pattern; solution-dying method provides excellent color fastness under the effects of sunlight, perspiration, air contaminants and washing

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Production method

• Purified cellulose from wood pulp or cotton linters. • Mixed with glacial acetic acid, acetic anhydride, and a catalyst • Aged 20 hours- partial hydrolysis occurs • Precipitated as acid-resin flakes • Flakes dissolved in acetone • Solution is filtered • Spinning solution extruded in column of warm air. Solvent

recovered • Filaments are stretched and wound onto beams, cones, or

bobbins ready for use

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Acetate fiber characteristics• cellulosic and thermoplastic • selective absorption and removal of low levels of certain organic chemicals • easily bonded with plasticizers, heat, and pressure • acetate is soluble in many common solvents (especially acetone and other organic solvents)

and can be modified to be soluble in alternative solvents, including water • hydrophilic: acetate wets easily, with good liquid transport and excellent absorption; in textile

applications, it provides comfort and absorbency, but also loses strength when wet • acetate fibers are hypoallergenic • high surface area • made from a renewable resource: wood pulp • can be composted or incinerated • can be dyed, however special dyes and pigments are required since acetate does not accept

dyes ordinarily used for cotton and rayon (this also allows cross-dyeing) • resistant to mold and mildew • easily weakened by strong alkaline solutions and strong oxidizing agents. • can usually be washed or dry cleaned; generally does not shrink

Viscoelastic Behavior of Cellulose Acetate

• Cellulose acetate (CA)/N,N-dimethylacetamide (DMA)/water• phase-separated gel formation• beta (1-4)-linked anhydroglucopyranose units(AGU)• substituted at the C-2, 3-, and 6-positions of the AGU• DS 0.5-1 soluble in aqueous solutions• (DMA) dissolves CA of DS ranging from 0.49 to 2.92• Solvent evaporation, changes in temperature, or the addition of a

nonsolvent• sol-gel transition• Hansen hydrogen-bonding solubility parameter index• Confocal scanning laser microscopy (CSLM)

Mixed cellulose esters (MCE)

Cellulose acetate-propionate (CAP)Cellulose acetate-butyrate (CAB) thermoplastic applications

Cellulose acetate-phtalates coating applications

mixed acetic-aliphatic cellulose esters high hydrophobicity

butyric or hexanoic anhydrides or maleic anhydride

Water contact angles

Water contact angles

Water vapor sorption

منابع مهم مورد استفادهhttp://en.wikipedia.org/wiki/Cellulose_acetatehttp://en.wikipedia.org/wiki/Cellulosehttp://chemistry.about.com/od/factsstructures/ig/ChemicalStructures/CelluloseAcetate.htmhttp://www.qrbiz.com/buy_cellulose-acetate-pelletshttp://chemical.ihs.com/nl/Public/2009/0908/0908.htmlhttp://renewablemat.bse.vt.edu/teaching/BSE%204514/Lecture%203%20http://staffweb.itsligo.ie/staff/mabroaders/webbased/Envsci/ES4/WM%http://www.ri.cmu.edu/pub_files/pub4/lopez_george_2004_1/lopez_george_2004_1.pdfhttp://www.che.ncsu.edu/khangroup/Papers/Appaw_Biomacromolecules_2007.pdfCallum A.S. Hill, Wood Modification: Chemical, Thermal and Other ProcessesCollins Appaw,Richard D. Gilbert,Saad A. Khan, Viscoelastic Behavior of Cellulose Acetate in a Mixed Solvent systemJérôme Peydecastaing, Chemical modification of wood by mixed anhydridesMinna Blomstedt,MODIFICATION OF CELLULOSIC FIBERS BY CARBOXYMETHYL CELLULOSEMonica Ek,Göran Gellerstedt,Gunnar Henriksson,Pulp and Paper Chemistry & TechnologyPaul Gatenholm,Hemicelluloses:Science and TechnologyPeter Zugenmaier, Crystalline Cellulose and Derivatives, 2008 Springer