Cotton Fiber: Physical And Chemical Properties Of Cotton

Cotton Fiber

Cotton is a cellulosic fiber. It is important to know the physical and chemical properties of this valuable fiber. Firstly, it has worldwide popularity for its variety of uses. Besides, it is the most used fiber for producing various types of fabric all over the world. Cotton fabrics are more comfortable to wear than other fiber products. After all, it is comfortable to wear in all seasons. If this fiber is properly ginned, it becomes soft, which makes it easy to use for dyeing when it has a high absorbency power. It has good strength and good drape ability at the same time.

Like all textile fibers, cotton has its own physical and chemical properties, which require knowledge for better processing in spinning, weaving, knitting, dyeing, printing, and finishing. It is important to know the physical and chemical properties of this fiber. Here, I describe the properties of cotton fiber.

Physical Properties of Cotton

The following are the physical properties of cotton fibers:

  1. Color: The color of cotton fiber could be white, creamy white, bluish-white, yellowish white, or grey.
  2. Tensile Strength: It is a moderately strong fiber. Moreover, it has a tenacity of 3-5 g/den. Moisture affects the strength of cotton greatly when the wet strength of cotton is 20%, which is higher than the dry strength.
  3. Elongation at break: It does not stress easily. It has an elongation at a break of 5–10%.
  4. Elastic Recovery: This is an inelastic and rigid fiber. Although at a 2% extension it has an ER of 74%, at a 5% extension it has an ER of 45%.
  5. Specific Gravity: The specific gravity of this fiber is 1.54.
  6. Moisture Regain (MR%): The standard moisture regain of cotton is 8.5.
  7. Effect of Heat: It has excellent resistance to degradation by heat. But it begins to turn yellow after several hours at 120 °C and decomposes at 150 °C. As a result of oxidation, this fiber becomes damaged several times after a few minutes at 240 °C. Lastly, cotton burns in the air.
  8. Effect of Sunlight: There is a gradual loss of strength when it is exposed to sunlight, and the fiber turns yellow. The degradation of this fiber by oxidation happens when heat promotes and encourages it. Altogether, sunlight causes much of the damage caused by UV light and by the short wavelengths of visible light.
  9. Effect of Age: It shows a small loss of strength when stored carefully. After 50 years of storage, this fiber may differ only slightly from the new fibers.
Physical And Chemical Properties Of Cotton

Chemical Properties of Cotton

It is a natural cellulosic fiber, and it has some chemical properties. The following are the chemical properties of this fiber:

  1. Effect of Acids: It is attacked by hot dilute acids or cold concentrated acids, which disintegrate. Indeed, it is not affected by acids.
  2. Effects of Alkalis: These have excellent resistance to alkalis. It swells in caustic alkalis (NaOH), but it does not damage. However, it can be washed repeatedly in a soap solution without any problem.
  3. Effect of Organic Solvent: It has high resistance to normal cleaning solvents. Meanwhile, this fiber is dissolved by the copper complexes, such as cuprammonium hydroxide and cupriethylene diamine, and concentrated at 70% H2SO4.
  4. Effects of Insects: It is not attacked by moth-grubs or beetles, at least.
  5. Effect of Microorganisms: This fiber is attacked by fungi and bacteria. Mildew will feed on fabric, rotting and weakening the materials. Mildew and bacteria will flourish on it under hot and humid conditions. They can be protected by impregnation with certain types of chemicals. One of the substances is copper naphthenate.

The above physical and chemical properties will indeed help us to be careful about the processing of this fiber in the different stages of processing, from spinning to garment making.

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