*3.1.2 Cotton fiber*

Raw cotton is being used as a material for clothing for a long and its origin can be traced to 2200 BC. The cotton hair during its growth is almost cylindrical and contains a central canal called is the lumen. When remove from the seed, however the cell collapse into a flat ribbon which forms an irregular spiral band under the influence of light and air.

The cotton fibers are having different lengths. These depend upon the types of soil, weather condition, duration of harvesting the crops, etc. the length of cotton fibers are expressed in the terms of staple length. Very good fibers measure a length of 2 inches. The length of fiber also depends on the fineness of the fibers, longer the fiber finer will be the diameter. The length of cotton fiber varies from 1200 to 1300 times its width.

*Strength and Elasticity:* Cotton is a strong fiber among the natural fibers; the cotton gets additional strength in wet conditions. In addition to strength, cotton possesses good elasticity. Tenacity Dry 2.1–6.3 gpd and Wet 110–130% Dry.

*Color:* Usually cotton fibers are creamy white in color. Most of Egyptian cotton has a yellowish-brown color.

*Luster:* Among the important natural fibers cotton has the lowest luster which however can be improved by mercerization. To reduce the luster, delustering agents are used.

*Effect of temperate:* Cotton fibers ignite easily and burn to produce a smell that is obtained by burning paper or wood.

*Exposure to heat:* There is no visible change until a temperature of 120°C is reached. At this temperature, cotton becomes yellowish after 5 hours of exposure but shows little change in strength. At 140°C the color changes to brown and develops a serious loss of strength. Again, when heated for a few hours at 240°C, it loses its complete strength.

*Moisture relation:* The percentage of moisture in the fiber influences the spinning quality of fiber. Cotton cannot be spun satisfactorily in a dry atmosphere. Cotton contains 7–8.5% of moisture regain. Fabrics made from these fibers get soiled and crushed easily, but they can be washed and ironed without causing damage.

*Effect of light:* Cotton fibers are affected by ordinary light and more particularly by ultraviolet rays and they lose their strength to some extent. Cotton has the least resistance to exposure to sunlight.

*Action of Acid:* Cotton fibers are degraded by strong acids like HCl, H2SO4, and HNO3. Dilute solutions of these acids if washed immediately to no harm, organic acids like acetic acid do not harm cotton fibers.

*Action of Alkalis:* Dilute alkalis at room temperature do not injure cotton. If cotton is boiled in a dilute solution of an alkali-like caustic soda in the presence of air, it turns yellow and loses its strength.

*Dyeability:* Cotton can easily be dyed using direct, sulfur, naphthol, vats, reactive and similar types of dyes.

*Application for cotton fibers:* It is used in summer wear, towelings, furnishings, medical textiles, canvas, sewing threads, dress material jeans and in sewing thread, etc.

### *3.1.3 Kapok fiber*

Kapok is a silky fiber obtained from the pod of kapok tree. The botanical name is Ceiba pentranda of the family Boombacaceae. This tree is grown principally in Java, Africa, Netherlands, and South East Asia, where the soil and hot climate conditions are especially suited for its growth. The fibers are contained in the outer shell, loosely surrounding the seeds and entirely free from the cell. The Kapok fiber has a hollow structure with an external radius of around 8.25 (±4) mm, internal diameter around 7.25 (±4) mm, and length around 25 (±5) mm. Combined with the specific material density of 1.3 g/cm3 .

*Application:* Kapok fibers are moisture-resistant, resilient, soft, and brittle. This fiber is not suitable for spinning but it is very much suitable for stuffing. So, this fiber is mostly used in jackets, sleeping bags, insulating materials, and upholstery.

#### **3.2 Bast fiber**

Basically are the bast fiber category in Jute, Flex, Hemp, Ramie, etc. [9].

### *3.2.1 Jute fiber*

Jute fiber is moderately strong, lustrous & yellowish-brown in color. It tends to disintegrate in water and has poor elasticity. However, this rigidity becomes virtuous. It is our best bagging material. Jute is difficult to bleach and it cannot be made pure white. It is the most important among all bast fibers. It is 2rd only to cotton in terms of crop polymer. It is easy to be spun but deteriorates when exposed to moisture. It can be converted wool-like fiber by treatment with strong caustic soda. It is highly hygroscopic with moisture regain of 13.75% and moisture content of 12% and the staple length of the fiber varies between 60 and 120 inches. Its color varies from yellow to brown. Generally, fiber is coarser and it is harsh. It is attacked by bacteria when damp. Jute is mixed with wool. Jute cloth is used for covering the cattle during winter because of its thermal insulation properties. It can be used for backing cloth for carpets and in the making of gunny bags, ropes, etc. it can be substituted for plywood also [10, 11].

*Application:* Jute is used for hessian sacking, backing for rugs, webbing, carpets, wall coverings, thread, canvas, matting, hammocks & beltings.

#### *3.2.2 Flex fiber*

Flax is also called as linen and many times it is called as linen, when it is turned into yarn or fabric. This is known very well around the world as the oldest of all the cultivated fiber raw materials. Flax is the bast fiber found in the stem of the plant "Linium usitatissium". The plant is cultivated in cold and humid conditions. So, the plantation is centered in cold countries. The major source of supply of flax is from the old U.S.S.R. the other countries which have flax growing areas are North Ireland, Egypt, Japan, Brazil, France, U.S.A., Australia, Canada, etc. Like jute, flax is an annual plant. The plant from which the fiber extracts grows in moist and cold conditions. The plant grows up to 160 to 170 cm in height and 1.5 cm in diameter. The tree is matured by changing its color from green to yellow. The flax fiber color is yellowish to gray, length 18 to 30 inches, elongation at a break of 2.7 to 3.5%, and moisture regain 10 to 12% [12].

*Application:* The flax fibers are used in household clothing fabrics, lace, sheetings, canvas, threads, papermaking, and industrial application like a fire house.

#### *3.2.3 Hemp fiber*

Basically hemp fiber is bast fiber category and similar harvesting process like for the flex fiber. These fibers are thick as compared to flax and darker color, tough to bleach process. This fiber is strong and more durable. The strands of the hemp fiber, approximate length of 6 to 8 feet and fiber length of 1.2 to 2.5 cm. The hemp fiber cross-section is polygonal shape and fiber is very stiff and surrounds considerable lignin. They are hemp fiber to produce for the coarse count cloths like sack material, rope, canvas, etc. Generally, hemp fiber is color yellowish to deep brown and moisture regains 12%. The hemp fiber is very poor elasticity recovery performance [13].

*Basic Functional Application for Natural Fibers and Types DOI: http://dx.doi.org/10.5772/intechopen.102998*

*Effect of acid:* Hemp is attacked by hot dilute acid or cold concentration acids which it breaks down.

*Effect of alkalis:* Hemp fiber has excellent resistance to alkalis.

*Effect of organic solvent:* It does not affect by the organic solvents.

*Application:* The coarse hemp fibers to produced yarn are used in woven into cordage, rope, sacking and heavy duties tarpaulins and fine hemp fibers are used for hats, shawls, rugs, towels.

### *3.2.4 Ramie fiber*

The ramie fiber is also bast fiber categories and generally to known this fiber as a china grass. All produced fiber processes are similar to hemp fiber. The ramie fiber is a white color with more luster and good strength. This fiber is basically used for industrial application and furnishing where rough, irregular clothes are desired. The plant grows to a height of 1 to 3 meters with a diameter of approximately 8 to 20 mm thick. The plant requires a tropical climate, where the winter temperature should be above freezing. This plant is also grown in India Australia, America, Japan, Brazil, etc. Ramie is a perennial fiber, with a yield from two to five crops of fiber per year, which depends upon the soil and climate. Ramie is ready for harvesting when the lower part of the stalk turns light yellowish-brown and the lower leaves matured by turning yellow and detachable. Harvesting is done by cutting the stalks. The physical properties of Ramie fiber exhibited high tenacity, high luster, and brightness. It has resistance to heat, light, acid, and alkali, etc. The ramie fiber is moisture regain used 12% [14, 15].

*Application:* In general, the fiber is strong, stiff with silky luster. The ramie fiber is used for sailcloth, ropes, fishnets, paper making, and upholstery fabric.

#### **3.3 Animals fibers**

They basically are used for animal fiber like wool and silk.
