Whatman cf11 fibrous cellulose nitrate

Cellulose acetate Kemisk structure, egenskaber and anvendelser

the cellulose acetate It has an organisk and syntetisk forbindelse, which can be opnås in almost the state of the storage, storage or hvidt powder. Dens molecular formula er C76H114O49. That he lavet af råmaterialet fra planter: cellulose, som er et homopolysaccharide.

Cellulose acetate blev først Fremdstillet in Paris, in 1865 by Paul Schützenberger and Laurent Naudin efter acetylering of cellulose med eddikesyreanhydrid (CH3CO-O-COCH3). De opnåede en af ​​the most important cellulose esters af all tiders.

If there are any such items, the polymer is bestemtil foreignstilling af plast til film, photographs and technical equipment, havde sit fantastiske øjeblik.

The bruges selv i bilindustrien and airfartsindustrie, and it is necessary i kemi and forskningslaboratorier in general.

indeks

  • 1 Kemisk structure
  • 2 Erhvervelse
  • 3 Egenskaber
  • 4 anvendelser
  • 5 referencers

Kemisk structure

Structures af cellulosetriacetatet, en af ​​de acetylerede former af denne polymer, he vist i det øvre billede ..

Hvordan forklares what structure? It is clear about cellulose, which is best about pyranoseringer af glucose formed with glycoside binding agent (-R-O-R) with carbon 1 (anomer) and 4.

These glycoside binders he af p1 -> 4 types; the vil sige, which he in the same plan som wrestling with hensyn til groups -CH2OCOCH3. Derfor bevarer din acetate ester det all organiske skeletons.

Hvad ville der ske, hvis OH groups i de 3 carbonatomer i cellulosetriacetatet blev acetyleret? Det ville øge den steriske (rumlige) spænding in sin structure. Dette er fordi groups -OCOCH3 "Collide" with nabogrupper and glucose rings.

More often because of the reaction to cellulose acetate butyrate, the product is available with the highest degree of acetylering, and the polymer has an endnu more flexible.

Forklaringen på denne flexibility he elimineringen af ​​the sidste OH group and derfor af hydrogenbindingerne mellem polymerkæderne.

In fact, the oprindelige cellulose in status til there was a lack of hydrogen binding, and elimineringen af ​​these he støtten, the forklarer changes af the physical-kemiske efter acetylering.

Således forekommer acetylering first in the lower sterisk hindrede OH group. Når concentrations of eddikesyreanhydrid øges, reimbursed for all H-groups.

Som et result, mens disse grupper -OCOCH3 de øger polymerens vægt, whose intermolecular interactions are less strong and hydrogen-binding, "fleksibiliserer" and hærder cellulosen on the same.

opnå

Dens foreignstilling amounts to som en simpel proces. Cellulose extra fra tracer mass or bomulds mass, som udsættes for hydrolysis reactors under forskellige betingelser for tid and temperature ..

Cellulose reagerer with eddikesyreanhydrid i et svovlsyremedium, som catalyser reactions.

On the basis of the need for celluloses, and the opnås en less polymer contained 200 to 300 glucose heder pr. Polymer kæde, idet hydroxyls from celluloses, replaced from acetate groups.

The final result af the reaction he et hvidt almost product, which can have a powder, scale or lump concentration. Herved can fibers uddybes, når de passerer gennem porer or huller i et medium with warm air, fordampes opløsningsmidlerne.

These complex processes are open to all types of cellulose acetate depending on the degree of acetylering.

Fordi cellulose has monomeric structural components of glucose, which has 3 OH groups, which can be acetylated, opnås di, tri eller endog butyrate acetates. This group -OCOCH3 he ansvarlige for nogle af deres egenskaber.

egenskaber

Cellulose acetate has a melting point of 306 ° C, the density is from 1.27 to 1.34 and has an average molecular weight of 1811.699 g / mol.

It is resistant to hazardous organic components, including acetones, cyclohexanol, ethyl acetate, nitropropane and ethylene dichloride.

Products, the indeholder flexibility of cellulose acetate, hardhed, trækstyrke, må ikke attacks on bacteria or microorganisms and their independent control over for vand.

Imidlertid has fiber dimensional changes in overensstemmelse with extreme variations of temperature and jointed, selv from fiber modstår temperatureer op to 80 ° C.

applicator

Cellulose acetate finder mange anvendelser, blandt hvilke the following skiller sig ad:

- Membrane to foreign stilling af varer af plast, paper and cardboard. In the indirect effect of kemisk additive of cellulose acetate deskrives, after it is in contact with the feeder in packaging.

- På sundhedsområdet used the membrane with the shell in the diameters of the capillary, indlejret in the cylindrical shape, which opfylder functions of the artificial nyre- or hæmodialyseudstyr.

- Indenfor art and film industries, når the bruges som tynde film to film, photography and magnetic tape.

- I continue to be used in the technology industries like fiber to foreign stuffing af forskellige fabrics like rayon, satin, acetate and triacetate. Men det var moderigtigt, stod det ud for dets lave omkostninger, for lysstyrken and the skønhed, the gav til tøj.

- I bilindustrien, til foreign stilling of motor and chassis of forskellige type køretøjer.

- Inden for luftfartsområdet, til at belægge flyets vinger i krigstid.

- The bruges also in the data-cable laboratories and forskning. In general, it uses the external filling of the porous filter as an understoing for cellulose acetate membranes to the directing of electroforese or osmotic monitoring.

- Den bruges til Fremdstilling af cigaretfilterbeholdere, elektriske kabler, lakker og lakker, blandt mange andre anvendelser.

referencer

  1. Fischer, S., Thümmler, K., Volkert, B., Hettrich, K., Schmidt, I. og Fischer, K. (2008), Egenskaber og Anvendelser af cellulose acetate. Macromol. Symp., 262: 89-96. doi: 10.1002 / masy.200850210.
  2. Encyclopedia Britannica. Cellulose nitrate. Published April 30, 2018, from: britannica.com
  3. National Center for Biological Information. Pubchem. (2018). Published April 30, 2018, fra: pubchem.ncbi.nlm.nih.gov
  4. USA National Library of Medicine. Cellulose acetate. Published on May 2, 2018, fra: toxnet.nlm.nih.gov
  5. IAC International. PROGEL. Published on May 2nd, 2018, fra: iacinternacional.com.ar
  6. Alibaba. (2018). Membrane filter. Published on May 2, 2018, fra: spanish.alibaba.com
  7. Ryan H. (March 23, 2016). 21 Bright Red / Red. [Figure]. Published on May 2, 2018, fra: flickr.com
  8. Mnolf. (April 4, 2006). Electroforesis gel. [Figure]. Published on May 2, 2018, fra: en.wikipedia.org