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Cellulose triacetate
Cellulose triacetate.png
Names
Other names
2,3,6-Tri-O-acetyl cellulose; cellulose triacetate polymer; triacetylcellulose
Identifiers
ChemSpider
  • none
ECHA InfoCard 100.115.198 Edit this at Wikidata
Properties
variable
Molar mass variable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cellulose triacetate, (triacetate, CTA or TAC) is a chemical compound produced from cellulose and a source of acetate esters, typically acetic anhydride. Triacetate is commonly used for the creation of fibres and film base. It is chemically similar to cellulose acetate. Its distinguishing characteristic is that in triacetate, at least "92 percent of the hydroxyl groups are acetylated."[1] During the manufacture of triacetate, the cellulose is completely acetylated; whereas in normal cellulose acetate or cellulose diacetate, it is only partially acetylated. Triacetate is significantly more heat resistant than cellulose acetate.

History

Triacetate, whose chemical equation is [C6H7O2(OOCCH3)3]n, was first produced commercially in the U.S. in 1954 by Celanese Corporation. Eastman Kodak was a manufacturer of CTA until March 15, 2007. For almost 3 years, Mitsubishi Rayon Co. Ltd. was the only manufacturer. In 2010, Eastman Chemical announced a 70% increase in cellulose triacetate output at its Kingsport (TN) manufacturing site to achieve the increasing demand for the chemical's use as an intermediate in the production of polarized films for liquid crystal displays.[2][3]

Production

Triacetate is derived from cellulose by acetylating cellulose with acetic acid and/or acetic anhydride. Acetylation converts hydroxyl groups in cellulose to acetyl groups, which renders the cellulose polymer much more soluble in organic solvents. The cellulose acetate is dissolved in a mixture of dichloromethane and methanol for spinning. As the filaments emerge from a spinneret, the solvent is evaporated in warm air, in a process known as dry spinning, leaving a fibre of almost pure triacetate.

A finishing process called S-Finishing or surface saponification is sometimes applied to acetate and triacetate fabrics using a sodium hydroxide solution. This removes part or all of the acetyl groups from the surface of the fibres leaving them with a cellulose coating. This reduces the tendency for the fibres to acquire a static charge.

Applications

As a fibre

Triacetate fibres have a crenate cross section.

Characteristics

Usage scenarios

Triacetate is particularly effective in clothing where crease or pleat retention is important, such as skirts and dresses.

In the 1980s triacetate was also used with polyester to create shiny tracksuits. The fabric was smooth and shiny on the outside and soft and fleecy on the inside.

General care tips

As a film

Main article: Safety film

Characteristics

Usage scenarios

As a semipermeable membrane

Usage scenarios

See also

References

  1. ^ Federal Trade Commission definition
  2. ^ "Eastman increasing cellulose triacetate capacity". timesnews.net. Associated Press. November 3, 2010.
  3. ^ Lindsey Bewley (November 1, 2010). "Eastman to Boost Cellulose Triacetate Capacity at Kingsport". IHS Chemical Week.