1. Structure and composition:

CMC (carboxymethylcellulose):

CMC is a derivative of cellulose, a natural polymer found in plant cell walls.
Cellulose molecules undergo a chemical modification process called carboxymethylation, in which carboxymethyl groups (-CH2-COOH) are introduced into the cellulose backbone.
The degree of substitution (DS) represents the number of carboxymethyl groups per glucose unit in the cellulose chain.

starch:

Starch is a carbohydrate composed of glucose units linked together by α-1,4-glycosidic bonds.
It is a polysaccharide that is the primary energy storage molecule in plants.
Starch is made up of two main components: amylose (straight chains of glucose units) and amylopectin (branched chains).

2. Source:

Sodium carboxymethyl cellulose:

CMC is typically derived from cellulose-rich plant sources such as wood pulp, cotton, or other fibrous plants.
The carboxymethylation process converts cellulose into water-soluble and more versatile compounds.

starch:

Starch is found in large amounts in a variety of plants, including cereals (e.g., corn, wheat, rice) and tubers (e.g., potatoes, cassava).
The extraction process involves breaking down the cell walls to release the starch granules.

3. Solubility:

Sodium carboxymethyl cellulose:

CMC is highly water-soluble due to the introduction of carboxymethyl groups, which imparts hydrophilicity to the molecule.
It forms clear, viscous solutions in water and is suitable for a variety of applications in industries such as food, pharmaceuticals and cosmetics.

starch:

Starch is generally insoluble in cold water.
However, heating starch in water causes it to swell and eventually gelatinize, forming a colloidal suspension.

4.Rheological properties:

Sodium carboxymethyl cellulose:

CMC exhibits pseudoplastic behavior, meaning that its viscosity decreases with shear stress.
This property is valuable in applications where viscosity control is critical, such as the formulation of paints, adhesives and food products.

starch:

Starch-based systems can gelatinize, forming gels with unique rheological properties.
Starch gels are essential in the food industry for thickening and gelling applications.

5.Industrial application:

Sodium carboxymethyl cellulose:

Widely used in the food industry as a thickener, stabilizer and humectant.
It is commonly used in pharmaceuticals due to its binding and disintegration properties in tablet formulations.
Found in various personal care products such as toothpaste and facial creams.

starch:

The main ingredient in the food industry, it has thickening, gelling and texturizing effects.
Used in the production of biodegradable plastics and as a source of fermentable sugars in ethanol production.
For sizing and coating in the paper industry.

6. Biodegradability:

Sodium carboxymethyl cellulose:

CMC is biodegradable and therefore has environmentally friendly properties.
Its use in various industries is in line with the growing demand for sustainable and environmentally friendly materials.

starch:

Starch is also biodegradable, making it a suitable choice for environmentally friendly applications.
The biodegradability of starch-based materials helps reduce environmental impact.

7. Film-forming performance:

Sodium carboxymethyl cellulose:

CMC can form films with good mechanical strength and flexibility.
This property is used in the production of edible films and food coatings.

starch:

A starch film is formed through the gelatinization process.
These films find application in packaging, where biodegradable materials are preferred.

8. Conductivity:

Sodium carboxymethyl cellulose:

CMC solutions exhibit a certain degree of conductivity due to the presence of carboxyl groups.
This property is exploited in certain applications, such as the electrochemical industry.

starch:

Starch does not have significant electrical conductivity.

9. Conclusion:

CMC and starch differ in structure, origin, properties and applications. CMC is derived from cellulose, is water-soluble, has pseudoplastic behavior, and is widely used in the food, pharmaceutical, and cosmetic industries. Starch is a polysaccharide that is insoluble in cold water but gels when heated, making it valuable in the food, paper and packaging industries. Both CMC and starch contribute to the development of sustainable and biodegradable materials, in line with the global emphasis on environmentally friendly solutions. Understanding these differences can help you make informed choices when choosing the right material for a specific industrial application.