Cellulose acetate
Description
A general name for thermoplastic polymers composed of the acetic acid ester of cellulose. Cellulose acetate was first developed by Schutzenberger in 1865. In 1908 it was introduced as safety film by Eastman Kodak and by 1910, with production by Dreyfus in France, acetate began replacing cellulose nitrate film. Cellulose acetate fibers were first manufactured commercially in Great Britain in 1919 (Celanese®). Cellulose acetate is prepared from cotton linters and/or purified wood pulp that is acidified, usually with Sulfuric acid, then acetylated with Acetic acid and Acetic anhydride. This produces cellulose triacetate; cellulose diacetate is obtained by partial hydrolysis to replace some of the acetyl groups with hydroxyl groups. Cellulose diacetate is commonly called acetate while the cellulose triacetate is called triacetate. Plasticizers, such as Glycol phthalate, Tributyl phosphate or Dibutyl phthalate, are added to cellulose acetate to increase flexibility. As the cellulose acetate ages, the plasticizers can migrate to the surface producing an oily film. Cellulose acetate resins are used in lacquers, photographic film, transparent sheeting and as fibers.
See also Acetate fiber, Cellulose diacetate, Cellulose triacetate, and Cellulose acetate butyrate.
Synonyms and Related Terms
CA; acétate de cellulose (Fr.); Celluloseacetat (Deut.); acetato de celulosa (Esp.); acetato di cellulosa (It.); acetato de celulose (Port.); safety film; secondary acetate
Examples: Celanese [British Celanese]; Kodacel [Eastman Kodak]; Tenite; Similoid;
Other Properties
Resistant to dilute alkalis and dry-cleaning solvents. Degrades in acids and concentrated alkalis. Soluble in acetone, phenol and chloroform.
Produces tiny sparks when burnt and gives faint odor of acetic acid.
Plasticized cellulose acetate: refractive index = 1.48-1.51
| Melting Point | 232 |
|---|---|
| Density | 1.25-1.35 |
| Refractive Index | 1.48 (pure) |
Hazards and Safety
Degradation produces volatile acetic acid. Plasticizer migration may result in oily or sticky surfaces.
Burns readily.
Degrades in sunlight, heat, and high humidity. Resistant to insects, slowly degraded by microorganisms.
Additional Information
Museum Handbook, Part 1. Museums Collections. Web Edition. Appendix M. Management of Cellulose Nitrate and Cellulose Acetate Films, NPS, 2001. http://www.cr.nps.gov/museum/publications/MHI/AppendM.pdf
Comparisons
Physical Properties for Selected Thermoplastic Resins
General Characteristics of Polymers
Sources Checked for Data in Record
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