Carboxymethylcellulose (CMC) is a functional additive widely used in various industries such as food, pharmaceuticals, papermaking, textiles, and mining. It is derived from natural cellulose, which is abundant in plants and other biological materials. CMC is a water-soluble polymer with unique properties including viscosity, hydration, adhesion and adhesion.
CMC characteristics
CMC is a cellulose derivative that is chemically modified by introducing carboxymethyl groups into its structure. This modification enhances the solubility and hydrophilicity of cellulose, thereby improving functionality. The properties of a CMC depend on its degree of substitution (DS) and molecular weight (MW). DS is defined as the average number of carboxymethyl groups per glucose unit in the cellulose backbone, while MW reflects the size and distribution of the polymer chains.
One of the key properties of CMC is its water solubility. CMC is easily soluble in water, forming a viscous solution with pseudoplastic properties. This rheological behavior results from intermolecular interactions between CMC molecules, resulting in a decrease in viscosity under shear stress. The pseudoplastic nature of CMC solutions makes them suitable for a variety of applications such as thickeners, stabilizers, and suspending agents.
Another important characteristic of CMC is its film-forming ability. CMC solutions can be cast into films with excellent mechanical properties, transparency, and flexibility. These films can be used as coatings, laminates and packaging materials.
In addition, CMC has good bonding and bonding properties. It forms a strong bond with different surfaces, including wood, metal, plastic and fabric. This property has led to the use of CMC in the production of coatings, adhesives and inks.
CMC viscosity
The viscosity of CMC solutions depends on several factors such as concentration, DS, MW, temperature, and pH. In general, CMC solutions exhibit higher viscosities at higher concentrations, DS, and MW. Viscosity also increases with decreasing temperature and pH.
The viscosity of CMC solutions is controlled by the interaction between the polymer chains and solvent molecules in the solution. CMC molecules interact with water molecules through hydrogen bonds, forming a hydration shell around the polymer chains. This hydration shell reduces the mobility of the polymer chains, thereby increasing the viscosity of the solution.
The rheological behavior of CMC solutions is characterized by flow curves, which describe the relationship between the shear stress and shear rate of the solution. CMC solutions exhibit non-Newtonian flow behavior, which means that their viscosity changes with shear rate. At low shear rates, the viscosity of CMC solutions is higher, while at high shear rates, the viscosity decreases. This shear thinning behavior is due to polymer chains aligning and stretching under shear stress, resulting in reduced intermolecular forces between chains and a decrease in viscosity.
Application of CMC
CMC is widely used in different fields due to its unique properties and rheological behavior. In the food industry, CMC is used as a thickener, stabilizer, emulsifier and texture improver. It is added to foods such as ice cream, drinks, sauces and baked goods to improve their texture, consistency and shelf life. CMC also prevents the formation of ice crystals in frozen foods, resulting in a smooth, creamy product.
In the pharmaceutical industry, CMC is used as a binder, disintegrant and controlled release agent in tablet formulations. Improve the compressibility and fluidity of the powder and ensure the uniformity and stability of the tablets. Due to its mucoadhesive and bioadhesive properties, CMC is also used as an excipient in ophthalmic, nasal, and oral formulations.
In the paper industry, CMC is used as a wet end additive, coating binder and sizing press agent. It improves pulp retention and drainage, increases paper strength and density, and provides a smooth and shiny surface. CMC also acts as a water and oil barrier, preventing ink or other liquids from penetrating the paper.
In the textile industry, CMC is used as sizing agent, printing thickener, and dyeing auxiliary. It improves fiber adhesion, enhances color penetration and fixation, and reduces friction and wrinkles. CMC also imparts softness and stiffness to the fabric, depending on the DS and MW of the polymer.
In the mining industry, CMC is used as a flocculant, inhibitor and rheology modifier in mineral processing. It improves settling and filtration of solids, minimizes separation from coal gangue, and controls suspension viscosity and stability. CMC also reduces the environmental impact of the mining process by minimizing the use of toxic chemicals and water.
in conclusion
CMC is a versatile and valuable additive that exhibits unique properties and viscosity due to its chemical structure and interaction with water. Its solubility, film-forming ability, binding and adhesion properties make it suitable for different applications in the food, pharmaceutical, paper, textile and mining sectors. The viscosity of CMC solutions can be controlled by several factors, such as concentration, DS, MW, temperature, and pH, and can be characterized by its pseudoplastic and shear-thinning behavior. CMC has a positive impact on the quality, efficiency and sustainability of products and processes, making it an essential part of modern industry.
Post time: Sep-25-2023