Cotton is a cellulosic fiber. It is important to know the physical and chemical properties of cotton fiber. Firstly, it has a worldwide popularity for its variety of use. Besides, cotton fiber is the most used fiber for producing various types of fabric all over the world. Cotton Fabrics are more comfortable to wear than the other fibers product. After all, it is comfortable to wear in all seasons. If cotton fiber is properly ginned it becomes soft and 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 to know for better processing in spinning, weaving, knitting, dyeing, printing as well as finishing. It is important to know the physical and chemical properties of cotton fiber. Here, I describe the physical and chemical properties of cotton fiber.
Physical Properties of Cotton:
The followings are the physical properties of cotton fibers. They are-
- Color: The color of cotton fiber could be white, creamy white, bluish white, yellowish white or grey.
- Tensile Strength: Cotton is moderately strong fiber. Moreover, it has a tenacity of 3-5 gm/den. Moisture affect the strength of cotton greatly when the wet strength of cotton is 20%, which is higher than dry strength.
- Elongation at break: Cotton does not stress easily. In fact, it has an elongation at break of 5-10%.
- Elastic Recovery: Cotton is inelastic and rigid fiber. Although, at 2% extension it has an ER of 74% and at 5% extension it has an ER of 45%.
- Specific Gravity: Specific gravity of cotton fiber is 1.54.
- Moisture Regain (MR %): Standard moisture regain of cotton fiber is 8.5.
- Effect of Heat: Cotton has an excellent resistance to degradation by heat. But, it begins to turn yellow after several hours at 1200C and decomposes marked by at 1500C. As a result of oxidation, cotton fiber becomes damage severally after few minutes at 2400C. Lastly, cotton burns in air.
- Effect of Sun Light: There is a gradual loss of strength when cotton exposes to sun light and the fiber turn yellow. The degradation of cotton by oxidation happens when heat promote and encourage. Altogether, by sun light much of the damage causes by UV-light and by the shorten weaves of visible light.
- Effect of Age: Cotton shows a small loss of strength when stored carefully. After 50 years of storage cotton may differ only slightly from the new fibers.
Chemical Properties of Cotton:
Cotton is a natural cellulosic fiber and it has some chemical properties. The followings are the chemical properties of the cotton fiber. They are-
- Effect of Acids: Cotton is attacked by hot dilute acids or cold concentrated acids which it disintegrates. Inded, it is not affected by acids.
- Effects of Alkalis: Cotton has an excellent resistance to alkalis. It swells in caustic alkalis ( NaOH) but it does not damaged. However, it can wash repeatedly in soap solution without any problem.
- Effect of Organic Solvent: Cotton has high resistance to normal cleaning solvents. Meanwhile, cotton is dissolved by the copper complexes, such as cuprammonium hydroxide, cupriethylene diamine and concentrated 70% H2SO4.
- Effects of Insects: Cotton is not attacked by moth-grubs or beetles at least.
- Effect of Micro Organism: Cotton is attacked by fungi and bacteria. Mildews will feed on cotton fabric, rotting and weakling the materials. Mildews and bacteria will flourish on cotton under hot and humid condition. They can be protected by impregnation with certain types of chemicals. Copper Nepthenate is one of the chemical for use.