Sodium carboxymethyl cellulose
A colorless, odorless, water-soluble polymer. Sodium carboxymethyl cellulose, NaCMC or CMC, was first developed in 1947. Commonly known as carboxymethyl cellulose, it is composed of the sodium salt of an alkaline modified cellulose. CMC is water-soluble but will react with heavy metal salts to form films that are clear, tough and insoluble in water. It is thixotropic, becoming less viscous when agitated. In most cases, CMC functions as a polyelectrolyte. It is used commercially in detergents, food product and as size for textiles and paper. In conservation, CMC has been used as an adhesive for textiles and paper. Aging studies indicate that most carboxymethyl cellulose (CMC) polymers have very good stability with negligible discoloration or weight loss (Feller and Wilt 1990).
Synonyms and Related Terms
carboxymethylcellulose; NaCMC; CMC; carboximetilcelulosa sódica (Esp.); carbossi metil cellulosa (It.); cellulose gum; sodium carboxymethylcellulose; CM cellulose;
Examples: Cellulose Gum CMC 7HSP [Aqualon]; Cellofas® B-3500 [ICI]; Cellosize® CMC P-75-M [Union Carbide]; Tylose® C [Hoechst]
Soluble in cold and hot water.
Insoluble in carbon tetrachloride, perchloroethylene and most organic solvents.
pH of a 1% solution is 6.5-8.0.
|Refractive Index||1.515 (dried film)|
Hazards and Safety
Finely divided dry dust is flammable.
R.L.Feller, M.Wilt, Evaluation of Cellulose Ethers for Conservation. Getty Conservation Institute, Los Angeles, 1990, p. 95.
Sources Checked for Data in Record
- Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
- Matt Roberts, Don Etherington, Bookbinding and the Conservation of Books: a Dictionary of Descriptive Terminology, U.S. Government Printing Office, Washington DC, 1982
- Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989
- Random House, Webster's Encyclopedic Unabridged Dictionary of the English Language, Grammercy Book, New York, 1997
- The American Heritage Dictionary or Encarta, via Microsoft Bookshelf 98, Microsoft Corp., 1998