we can define cotton as a cellulosic multilayer fiber, which contains; first wall, second wall and lumen channel. Qualities and properties of cotton fiber depend on the second wall which is made of cellulosic layers, the thicker the second wall is, the more mature the fiber is and under this situation it can show desirable mechanical and chemical properties of itself. The Cotton can be classified into three groups by its maturity; hard bodies (maturity is more than 84%), soft bodies (maturity is less than 67%) and fibers which have 68-76% maturity are medium. This fiber is thermoset and smells like paper when it burns.
Macrostructure properties of cotton fiber:
This fiber is staple and it is known as a short fiber because, the length of the fiber depends on the weather and genetic of the cotton. The longer the cotton fiber becomes, the finer fiber we have and its diameter would decrease.
Length classification of cotton fiber:
|High quality||26-65 mm|
|Medium quality||12-33 mm|
|Poor quality||9-26 mm|
Diameter classification of cotton fiber:
Cotton is a semitransparent fiber and because of the presence of convolutions in the fiber, it cannot be a radiant fiber. There are some impurities like pectin, dust, and wax in the cotton fiber that make the cotton different in color; white, gray, yellowish white.
Microstructure properties of cotton fiber:
Cotton fibers are ribbon-like and have convolution in their structure and their cross-section shape is not completely circular.
But why the cotton is important in world trade of textile…
cotton is hydrophilic and its moisture regain is about 7-8 % which makes the cotton breathable. By having these properties cotton can absorb dye and water.
The Crystallinity of this fiber is about 65-70% which means that cotton has suitable tensile properties. Cotton becomes stronger about 20% when it absorbs water. The breaking Elongation for this fiber is about 5-10%.
Cotton can be used with other fibers like PET and can be dyed in different ways.
All these properties demonstrate the reasons for the popularity of cotton in the world market.