Sodium carboxymethyl cellulose, abbreviated as CMC-Na, is a white to light yellow powder, granular, or fibrous substance with strong hygroscopic properties. It dissolves readily in water, forming a high-viscosity liquid in neutral or alkaline conditions. It remains stable in the presence of light, heat, and most chemical agents, though its thermal stability is limited to around 80°C. Prolonged heating above this temperature can cause a reduction in viscosity and eventual insolubility. The relative density is about 1.60 for the powdered form and 1.59 for flakes, with a refractive index of 1.515. It begins to discolor to brown at 190–205°C and carbonizes at 235–248°C. Its solubility in water depends on the degree of substitution (DS). CMC-Na is insoluble in acids and alcohols, does not precipitate upon salt addition, resists fermentation, and has excellent emulsifying ability for oils and waxes. It can be stored for extended periods without significant degradation.
This article includes the following content:
- Uses in oil and natural gas drilling, well construction, and similar projects
- Industrial applications
- Applications in food
For Oil and Natural Gas Drilling, Well Digging, and Related Projects
Mud containing CMC helps form a thin, strong, and low-permeability filter cake on the wellbore wall, effectively reducing water loss.
The addition of CMC to drilling mud lowers the initial gel strength, which allows entrapped gases to escape more easily and enables solid cuttings to be rapidly discarded in the mud pit.
Like other suspension fluids, drilling mud has a limited service life. Incorporating CMC stabilizes the mud and extends its usable duration.
CMC-containing mud is less susceptible to mold growth, eliminating the need for high pH maintenance or additional preservatives.
When used as a washing fluid treatment agent in drilling mud, CMC can resist contamination from various soluble salts.
Mud with CMC retains good stability and low water loss even at elevated temperatures above 150°C.
High-viscosity, high-DS CMC is suitable for low-density muds, while low-viscosity, high-DS CMC works better with high-density muds. The selection of CMC type depends on specific conditions such as mud composition, geographic region, and well depth.
Application in Industry
In the textile, printing, and dyeing industries, CMC serves as a sizing agent for yarns made from cotton, silk, wool, synthetic fibers, and blends, enhancing strength and smoothness.
In paper manufacturing, CMC functions as a smoothing and sizing agent. Adding 0.1–0.3% CMC to pulp can increase paper tensile strength by 40–50%, boost bursting strength by about 50%, and improve flexibility by 4–5 times.
CMC can be added to synthetic detergents as a soil-suspending agent. In toothpaste, the glycerol-water solution acts as a gelling base. In pharmaceuticals, it is used as a thickener and emulsifier. CMC solutions are also applied in mineral flotation as thickening and stabilizing agents.
In the ceramics industry, CMC is used as an adhesive, plasticizer, glaze suspending agent, and fixing agent.
Application in Food
Edible-grade CMC has thickening, emulsifying, shaping, moisture-retaining, and stabilizing properties. Its addition to foods can reduce production costs, improve product quality and taste, and extend shelf life, making it an ideal additive in the food industry. It is widely used in solid and liquid beverages, canned goods, candies, cakes, meat products, biscuits, instant noodles, quick-cooking foods, frozen snacks, soy milk, yogurt, peanut milk, fruit tea, juices, and other products. Usage levels and functions vary depending on the specific food application.
In summary, sodium carboxymethyl cellulose (CMC) is the most widely produced and applied cellulose ether, known for its versatility and ease of use—often referred to as the "industrial monosodium glutamate."
