Carboxymethylcellulose (CMC) and starch are both polysaccharides, but they have different structures, properties and applications.
Molecular composition:
1. Carboxymethylcellulose (CMC):
Carboxymethylcellulose is a derivative of cellulose, a linear polymer composed of glucose units connected by β-1,4-glycosidic bonds. Modification of cellulose involves the introduction of carboxymethyl groups through etherification, producing carboxymethylcellulose. The carboxymethyl group makes CMC water-soluble and gives the polymer unique properties.
2. Starch:
Starch is a carbohydrate composed of glucose units linked by α-1,4-glycosidic bonds. It is a natural polymer found in plants that is used as an energy storage compound. Starch molecules are generally composed of two types of glucose polymers: amylose (straight chains) and amylopectin (branched chain structures).
Physical properties:
1. Carboxymethylcellulose (CMC):
Solubility: CMC is water-soluble due to the presence of carboxymethyl groups.
Viscosity: It exhibits high viscosity in solution, making it valuable in various applications such as food processing and pharmaceuticals.
Transparency: CMC solutions are typically transparent.
2. Starch:
Solubility: Native starch is insoluble in water. It requires gelatinization (heating in water) in order to dissolve.
Viscosity: Starch paste has viscosity, but it is generally lower than CMC.
Transparency: Starch pastes tend to be opaque, and the degree of opacity may vary depending on the type of starch.
source:
1. Carboxymethylcellulose (CMC):
CMC is typically made from cellulose from plant sources such as wood pulp or cotton.
2. Starch:
Plants such as corn, wheat, potatoes and rice are rich in starch. It is a main ingredient in many staple foods.
Production Process:
1. Carboxymethylcellulose (CMC):
The production of CMC involves the etherification reaction of cellulose with chloroacetic acid in an alkaline medium. This reaction results in the replacement of hydroxyl groups in cellulose with carboxymethyl groups.
2. Starch:
Starch extraction involves breaking down plant cells and isolating starch granules. Extracted starch can undergo various processes, including modification and gelatinization, to obtain desired properties.
Purpose and application:
1. Carboxymethylcellulose (CMC):
Food industry: CMC is used as a thickener, stabilizer and emulsifier in various foods.
Pharmaceuticals: Due to its binding and disintegrating properties, it finds use in pharmaceutical formulations.
Oil Drilling: CMC is used in oil drilling fluids to control rheology.
2. Starch:
Food industry: Starch is the main component of many foods and is used as a thickening agent, gelling agent and stabilizer.
Textile industry: Starch is used in textile sizing to provide stiffness to fabrics.
Paper industry: Starch is used in papermaking to increase paper strength and improve surface properties.
Although CMC and starch are both polysaccharides, they have differences in molecular composition, physical properties, sources, production processes and applications. CMC is water-soluble and highly viscous and is often preferred in applications requiring these properties, while starch is a versatile polysaccharide widely used in the food, textile and paper industries. Understanding these differences is critical to selecting the appropriate polymer for specific industrial and commercial applications.
Post time: Jan-12-2024