CMC (Carboxymethyl Cellulose) is an anionic cellulose ether derived from the chemical modification of natural cellulose. It is widely used in industries such as food, pharmaceuticals, cosmetics, paper, textiles, and petroleum, primarily as a thickener, stabilizer, emulsifier, and water retention agent.
Chemical Structure
CMC is produced by reacting cellulose with chloroacetic acid (ClCH₂COOH) under alkaline conditions. Its chemical structure is as follows:
Cellulose-O-CH2COONa
Here, the carboxymethyl group (-CH₂COONa) replaces the hydroxyl group (-OH) in the cellulose molecule.
Key Properties
- Water Solubility:
- Easily dissolves in water, forming a transparent or semi-transparent colloidal solution.
- Thickening Ability:
- Provides excellent thickening effects, significantly increasing the viscosity of the system.
- Water Retention:
- Effectively prevents rapid water evaporation in construction materials.
- Stability:
- Exhibits good stability in acidic, alkaline, and saline solutions.
- Film-Forming Ability:
- Can form flexible and transparent films.
- Eco-Friendliness:
- Biodegradable and environmentally friendly.
Applications
- Food Industry:
- Used as a thickener, stabilizer, or emulsifier in products such as ice cream, yogurt, and sauces.
- Pharmaceuticals:
- Used as a drug release agent, capsule material, or tablet binder.
- Cosmetics:
- Used in emulsions, creams, and other products as a thickener and stabilizer.
- Paper Industry:
- Used as a surface sizing agent to improve the strength and water resistance of paper.
- Textile Industry:
- Used as a sizing agent to enhance the strength and wear resistance of yarns.
- Petroleum Industry:
- Used as a thickener and stabilizer in drilling fluids.
Role in Construction Materials
- Improved Workability:
- Enhances the lubricity and operability of mortars.
- Enhanced Water Retention:
- Prevents rapid water loss, improving the strength after hardening.
- Reduced Cracking:
- Minimizes shrinkage and cracking by improving water retention and cohesion.
- Increased Bonding Strength:
- Enhances the bonding performance between mortar and substrates.
Technical Parameters
- Degree of Substitution (DS): Typically ranges from 0.4 to 1.5, indicating the extent of carboxymethyl substitution on cellulose molecules.
- Viscosity: Available in different viscosities based on application requirements.
- Appearance: White or light yellow powder.
- Solubility: Easily dissolves in cold water, forming a transparent or semi-transparent solution.
Usage Methods
- Direct Addition: Add CMC directly to dry-mix mortars and mix thoroughly with other components.
- Pre-Dissolution: Dissolve it in water first, then add it to the system.
Storage and Handling
- Store in a cool, dry place to avoid moisture absorption.
- Keep the packaging sealed to prevent clumping.
- Avoid contact with strong acids, bases, or oxidizers.
Summary
CMC is a versatile polymer material widely used in the food, pharmaceutical, cosmetic, paper, textile, and petroleum industries due to its excellent thickening, water retention, and eco-friendly properties. If you need more information about its applications or technical details, feel free to ask!
