Cotton physical properties

Chemical composition of cotton:

Cotton fibers are composed  mostly  Alpha cellulose. The non cellulosics are located either on the outer layers(Cuticle and Primary cell wall) or inside the lumens of the fibers whereas the secondary cell wall is purely cellulose. The specific  chemical compositions  of the cotton fibers vary by their varieties,growing  conditions(soil ,water,temperature,pest etc) and maturity. Due to this reason we can express the average value of different component of cotton.

Constituents	Percent
Cellulose	94.0
Protein	1.3
Pectin Substance	1.2
Ash	1.2
Fat and Wax	0.6
Organic acid ,sugar and others	1.7

   

Of the non cellulosic components in the cotton fibres , the wax and pectins are mostly resposible for the hydrophobicity or low water wettability of the cotton fibers.

Properties of cotton fibers:

Cotton , a unique cellulosic fibers, Possesses an outstanding range of properties making it one  of the most popular apparel fibers worldwide.

Physical properties:

          I.            Length and Width: Cotton is the shortest natural fiber used in commercially in the textile industry ranging from 0.5-2.5 inches in length. The width of typical cotton fiber may vary between 12 to 20 microns.

        II.            Shape: A typical, matured raw cotton fiber looks like a flattened tube and cross section is oval or kidney shape. Under  microscope , it is a long twisted ribbon.

      III.            Strength: Tenacity of a cotton a  fiber is a  26.5-44 cN/TEX  and the extension at break is about 8-10%.

     IV.            Elasticity: Cotton is relatively rigid fiber(Less elastic) .At 2% extension is has an elastic recovery 74% , at 5% extension , the elastic recovery is only 45%.

       V.            Porosity:  Cotton fiber is somewhat porous, and consequently, it absorbs moisture readily.

     VI.            Moisture Regain:  Due to presence of a large number of OH groups ,cotton fibers are very  hygroscopic in nature and contain moisture also in normal  dry condition ( air- dry ) . In a standard atmosphere of 65% RH and 20°C, cotton has a moisture regain 7-8%. The recommended allowance for calculating the mass of fibre in commercial transaction is 8.5% .At 100% humidity , cotton has an absorbency of 25-27%

   VII.            Color: Normally , the color of cotton is creamy white.

 VIII.            Handle: Cotton is naturally very soft and comfortable , that is why it is particularly  favored for garments that get close to the skin.

      IX.            Luster: Cotton fibers have a natural luster which due to natural polish on the surface and its nearly cross sectional shape.