Acetate and Triacetate
Definition: Acetate is "a manufactured fiber in which the fiber-forming substance is cellulose acetate.
Where not less than 92% of the hydroxyl groups are acetylated, the term triacetate may be used as a generic description of the fiber" (Source- Textile Fiber Products Identification Act, Federal Trade Commission). Acetate was
the second manufactured fiber to be developed.
- Acetate and triacetate are modified cellulosic fibers also known as
derivative cellulosic fibers. They are produced by acetylation (replacing the
hydroxyl groups with acetyl groups) of the cellulose molecule. Replacing the
hydroxyl groups with acetyl groups changes the polymer and fiber properties.
- Due to the changes in the polymer structure, acetate and triacetate fibers
could not be dyed with the dyes available when these fibers were initially
developed. A new class of dyes, known as disperse dyes, was created.
- One of the major drawbacks in dyeing acetate with certain disperse dyes
was poor colorfastness to atmospheric fumes. As a result, blue fabrics changed
to pink, green to brown, and gray to red/pink. With advancement in technology,
solutions are now available that address the problem of fume fading.
Inhibitors and improved dyes can prevent fume fading of acetate fibers.
- Triacetate is no longer produced in the U.S. because the use of methylene
chloride as a solvent for fiber manufacturing was banned by the Environmental
Protection Agency (EPA).
- Surface Contour (longitudinal view) - Acetate and triacetate fibers have striations along the fiber length. The striations are due to the change in surface characteristics when the solvent evaporates during the spinning process. Fibers extruded through spinnerets with circular cross-sections "shrink," resulting in striations along the surface. These are similar, but not as numerous as the striations seen in viscose rayon.
- Shape (cross-section) - Acetate and triacetate extruded through spinnerets with circular holes have a crenulated, crumpled multilobal cross-section because of the collapsing of the round filament as the solvent evaporates. The cross-section can be varied by changing the shape of the spinneret holes.
- Luster - Acetate and triacetate fibers are inherently lustrous. Delusterant is added to produce semi-dull and dull fibers.
- Size - Acetate and triacetate, like other manufactured fibers, can be produced in varying sizes based on the intended end use.