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Sodium carboxymethyl cellulose (Na-CMC) is one of the most widely used water-soluble cellulose derivatives.
It is a polyanionic polysaccharide obtained from cellulose, the most abundant natural polymer, through chemical modification involving substitution of hydroxyl groups with carboxymethyl groups.
This structural modification enhances water solubility, colloidal stability, and functional versatility, making it highly valuable in industries such as food, pharmaceuticals, cosmetics, petroleum, paper, and textiles.
CAS Number: 9004-32-4
SYNONYMS:
CMC,Cellulose gum,Carboxymethylcellulose sodium salt,Sodium salt of carboxymethylcellulose,Cellulose carboxymethyl ether, sodium salt
Historical Background
Cellulose was first chemically modified in the 19th century to obtain derivatives with improved solubility and functionality.
In the 1920s–1930s, sodium carboxymethyl cellulose was first synthesized and studied as a water-soluble derivative of cellulose.
By the 1940s, it became commercially available and was rapidly adopted in the food and pharmaceutical industries due to its stability and safety.
Over decades, extensive research expanded its applications into oil drilling, paper manufacturing, detergents, coatings, adhesives, and biomedical products.
Chemical Structure and Properties
Chemical Formula
The repeating unit of sodium carboxymethyl cellulose can be expressed as:
[C6H7O2(OH)2OCH2COONa]n
Molecular Structure
CMC is derived from cellulose, consisting of linear chains of β-(1→4)-linked D-glucose units.
During carboxymethylation, the hydroxyl groups at the C2, C3, and C6 positions of the anhydroglucose units are partially substituted by carboxymethyl (-CH2COONa) groups.
Degree of Substitution (DS)
DS ranges from 0.4 to 1.4 in commercial products.
A higher DS increases water solubility and viscosity.
Physical Properties
Appearance: White to off-white powder or granules
Solubility: Readily soluble in cold and hot water; insoluble in most organic solvents
Viscosity: Varies from low (10 mPa·s) to very high (>10,000 mPa·s) depending on molecular weight and DS
pH of aqueous solution: Typically 6.0–8.5
Hygroscopic nature: Tends to absorb moisture from the atmosphere
Thermal Properties
Decomposition starts around 200–250°C
Not meltable but forms stable films
Methods of Production
Raw Materials
Cellulose: Obtained from wood pulp or cotton linters
Sodium hydroxide (NaOH): Used for alkalization
Monochloroacetic acid (MCA) or its sodium salt: Used for carboxymethylation
Process Steps
Alkalization: Cellulose is treated with NaOH in an alcohol medium to form alkali cellulose.
Etherification (Carboxymethylation): Alkali cellulose reacts with monochloroacetic acid or sodium monochloroacetate, producing sodium carboxymethyl cellulose.
Purification: Unreacted chemicals, salts, and by-products (such as sodium chloride and sodium glycolate) are removed by washing, filtration, and drying.
Drying and Milling: The purified product is dried and milled to the required particle size.
Variants
Technical grade CMC: Used in detergents, textiles, paper, and drilling fluids
Food and pharmaceutical grade CMC: Purified to minimize sodium chloride and sodium glycolate levels
Analytical Characterization
Degree of substitution (DS) determined by titration, FTIR, or NMR
Viscosity measured using Brookfield viscometers
Molecular weight analyzed by gel permeation chromatography
Purity tested by ash content, sodium chloride, and sodium glycolate levels
Functional group analysis by FTIR, Raman, and elemental analysis
Applications
Food Industry
Thickener, stabilizer, emulsifier in ice cream, sauces, dressings, bakery products
Fat replacer in low-calorie foods
Suspension agent in beverages
Pharmaceutical Industry
Binder and disintegrant in tablets
Suspension stabilizer in syrups and liquid formulations
Controlled release agent in drug delivery systems
Component of ophthalmic solutions as a lubricant
Cosmetics and Personal Care
Thickener in creams, lotions, shampoos, and toothpaste
Film-forming agent for moisture retention
Petroleum Industry
Used in drilling muds for viscosity control and water retention
Enhances oil recovery processes
Paper Industry
Surface sizing agent for better printability
Improves paper strength and coating properties
Textile Industry
Used as a thickener in textile printing pastes
Provides viscosity control for uniform dyeing
Detergents
Soil redeposition inhibitor
Stabilizes liquid detergent formulations
Biomedical Applications
Hydrogel formation for wound dressings
Scaffold material in tissue engineering
Carrier for enzyme immobilization
SAFETY INFORMATION ABOUT SODIUM CARBOXYMETHYL CELLULOSE
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
