triacetat

Triacetat, or cellulose triacetate (CTA), is a cellulose derivative produced by acetylating cellulose so that three acetyl groups replace the hydroxyls on each anhydroglucose unit. The resulting polymer is a triester of cellulose, more hydrophobic and thermoplastic than native cellulose. The degree of substitution approaches three, giving an acetyl content sufficient to render the material insoluble in water but soluble in certain organic solvents used for processing.

CTA is prepared by reacting cellulose with acetic anhydride in the presence of an acid catalyst, followed by purification. The acetyl content and molecular weight can be adjusted to produce grades suitable for fibre or film applications. Historically, cellulose triacetate was developed for high-performance films and fibres and remains a representative example of early cellulose esters.

In textiles, triacetate fibers were marketed as a smooth, drapable alternative to rayon and certain synthetics, offering good shape retention and a distinctive hand. They require specific dyeing and finishing processes. In film and optics, CTA served as a base material for photographic and motion-picture film, as well as for niche packaging and membrane applications, due to its dimensional stability and processing characteristics.

Key properties of CTA include good dimensional stability, moderate heat resistance, and resistance to many common solvents. It is thermoplastic and can be processed from solution or by extrusion under controlled conditions. CTA fibers and films are generally non-toxic when handled properly, but processing involves flammable organic solvents and acetic acid derivatives, necessitating appropriate ventilation and handling procedures.

Today, cellulose triacetate remains in use in specialized applications and as a historical example of cellulose ester technology, having largely given way to other polymers where performance and cost are optimized.