triacetaat

Triacetaat, in English known as cellulose triacetate (CTA), is the triester of cellulose in which the hydroxyl groups of the glucose units are fully acetylated. The molecule is derived from cellulose, a natural polymer, and features three acetyl groups per anhydroglucose unit.

Production and structure: CTA is prepared by acetylating cellulose with acetic anhydride in acetic acid, often with a catalyst. The typical degree of substitution is close to 3, meaning nearly all hydroxyls are acetylated. The resulting material is a thermoplastic polymer with good optical clarity and chemical resistance.

Properties and applications: CTA fibers are known for high dimensional stability, low moisture absorption, and a smooth hand. It is processed by solution spinning into fibers or by casting films. Historically important as a textile fiber and as a base for motion picture and photographic films. In textiles, it was dyed with disperse dyes; in films, it offered high clarity but was eventually surpassed by polyester.

Current status: Production has declined in many sectors due to the rise of polyester and other synthetics, but CTA remains in niche applications and legacy film stock, where a cellulose-derived, transparent, thermoplastic material is desired.