Production process and Uses of Cotton

Cotton:

Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium in the family of Malvaceae. The fiber is almost pure cellulose. Under natural conditions, the cotton bolls will tend to increase the dispersion of the seeds.

Types:

• Gossypium  hirsutum

• Gossypium  barbadense

• Gossypium  arboreum 

• Gossypium  herbaceum

Production: 

Organic cotton is generally understood as cotton, from plants not genetically modified, that is certified to be grown without the use of any synthetic agricultural chemicals, such as fertilizers or pesticides..

Genetically modified (GM) cotton was developed to reduce the heavy reliance on pesticides. The bacterium Bacillus thuringiensis (Bt) naturally produces a chemical harmful only to a small fraction of insects, most notably the larvae of moths and butterflies, beetles, and flies, and harmless to other forms of life.

Uses:

1. Cotton is used to make highly absorbent bath towels and robes. 

2. Most T-shirts are made from cotton.

3. Bed sheets often are made from cotton

4. Cotton also is used to make yarn used in crochet and knitting.

5. Cotton is used in fishing nets, coffee filters, tents, explosives manufacture, cotton paper, and in 

        bookbinding.

6. The first Chinese paper was made of cotton fiber.

Silk: 

Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the cocoons of the larvae of the mulberry silkworm Bombyx mori reared in captivity.

Properties:

1. Silk fibers from the Bombyx mori silkworm have a triangular cross section with rounded corners, 5–10         μm wide.

2. Silk has a smooth, soft texture that is not slippery, unlike many synthetic fibers.

3. Silk is one of the strongest natural fibers, but it loses up to 20% of its strength when wet.

4. Silk is a poor conductor of electricity and thus susceptible to static cling.

5. Silk is resistant to most mineral acids, except for sulfuric acid.

6. The addition of alanine and serine makes the fibers strong and resistant to breaking.

Production process: 

The entire production process of silk can be divided into several steps which are typically handled by different entities. Extracting raw silk starts by cultivating the silkworms on mulberry leaves. Once the worms start pupating in their cocoons, these are dissolved in boiling water in order for individual long fibres to be extracted and fed into the spinning reel.

Uses:

1. Silk's absorbency makes it comfortable to wear in warm weather and while active.

2. Its low conductivity keeps warm air close to the skin during cold weather. 

3.     It is often used for clothing such as shirts, ties,blouses, formal dresses, high fashion clothes, lining,        

        lingerie.

4. It is used for upholstery, wall coverings, window treatments (if blended with another fiber), rugs, 

        bedding and wall hangings.

5. Silk has had many industrial and commercial uses, such as in parachutes, bicycle tires.

6. Silk's attractive luster and drape makes it suitable for many furnishing applications.

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Properties and Production of Dacron

Dacron:

Polyethylene terephthalate is the most common thermoplastic polymer resin of the polyester family and is used in fibers for clothing, containers for liquids and foods, thermoforming for manufacturing, and in combination with glass fiber for engineering resins.

It may also be referred to by the brand name Dacron.

Properties:

1. PET in its natural state is a colorless, semi-crystalline resin.

2. PET can be semi-rigid to rigid, and it is very lightweight. It makes a good gas and fair moisture barrier,           as well as a good barrier to alcohol and solvents.

4.     It is strong and impact-resistant.

5.     PET becomes white when exposed to chloroform and also certain other chemicals such as toluene.

Production: 

Polyethylene terephthalate is produced from ethylene glycol and dimethyl terephthalate (C₆H₄(CO₂CH₃)₂) or terephthalic acid. Dimethyl terephthalate process:

Polyesterification reaction in the production of PET.

In dimethyl terephthalate process, this compound and excess ethylene glycol are reacted in the melt at 150–200 °C with a basic catalyst. Methanol (CH₃OH) is removed by distillation to drive the reaction forward. Excess ethylene glycol is distilled off at higher temperature with the aid of vacuum. The second transesterification step proceeds at 270–280 °C, with continuous distillation of ethylene glycol as well.The reactions are idealized as follows:

First step:

C₆H₄(CO₂CH₃)₂ + 2 HOCH₂CH₂OH → C₆H₄(CO₂CH₂CH₂OH)₂ + 2 CH₃OH

Second step:

n C₆H₄(CO₂CH₂CH₂OH)₂ → [(CO)C₆H₄(CO₂CH₂CH₂O)]_n + n HOCH₂CH₂OH

Cotton:

Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium in the family of Malvaceae. The fiber is almost pure cellulose. Under natural conditions, the cotton bolls will tend to increase the dispersion of the seeds.

Types:

• Gossypium  hirsutum

• Gossypium  barbadense

• Gossypium  arboreum 

• Gossypium  herbaceum

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Importance and Uses of Polyester Fibers

Polyester :

Polyester is a category of polymers that contain the ester functional group in their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). polyesters include occurring chemicals, such as in the cutin of plant cuticles, as well as synthetics through step-growth polymerization such as polybutyrate.

The main raw materials:

•  Purified terephthalic acid (PTA) or 1,4 benzenedicarboxylic acid,

• Dimethylterephthalate (DMT) or1,4 benzenedicarboxylic acid dimethyl ester

• Mono Ethylene Glycol (MEG) or 1,2 ethanediol

Production of Polyester: 

Synthesis of polyesters is generally achieved by a poly condensation reaction. The general equation for the reaction of a diol with a diacid is :

(n+1) R(OH)₂ + n R´(COOH)₂ → HO[ROOCR´COO]_nROH + 2n H₂O

Aliphatic polyesters can be assembled from lactones under very mild conditions, catalyzed anionically, cationically or metallorganically. A number of catalytic methods for the copolymerization of epoxides with cyclic anhydrides have also recently been shown to provide a wide array of functionalized polyesters, both saturated and unsaturated.

Importance of Polyester:

1.    The relatively easy accessible raw materials PTA or DMT and MEG

2.    The very well understood and described simple chemical process of polyester synthesis

3.  The low toxicity level of all raw materials and side products during polyester production and processing

4.    The possibility to produce PET in a closed loop at low emissions to the environment

5.    The outstanding mechanical and chemical properties of polyester

6.    The recyclability

7.    The wide variety of intermediate and final products made of polyester.

Uses of Polyester:

      1. Polyester fiber is used as cushioning and insulating material in pillows, comforters and upholstery padding.

    2. Polyesters are also used to make bottles, films, tarpaulin, canoes, liquid crystal displays, holograms, filters, dielectric film for capacitors, film insulation for wire and insulating tapes.

     3. Polyesters are widely used as a finish on high-quality wood products such as guitars, pianos and vehicle/yacht interiors.

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Production & Characteristics of Acetate Rayon

Characteristics of Acetate Rayon : 

     1. Feel natural and is gentle on the skin.
     2. Elegant gloss and chromogenic quality.
     3. Drapes lightly and flexibly.
     4. Ideal water absorption and quick-drying qualities.
     5. Does not shrink easily, so provides stability for dimensions and
     6. No worries of pilling.
     7.  Measurements. Relatively high temperature range for safe ironing.
     8. Does not stain easily, and stains are easy to remove.

Nylon :

Nylon is a generic designation for a family of synthetic polymers known generically as aliphatic polyamides. Nylon is one of the most commonly used polymers. Example : Nylon 6.

Characteristics :

     1. Variation of luster : nylon has the ability to be very lustrous, semilustrous or dull.
     2. High elongation
     3. Highly resilient (nylon fabrics are heat-set)
     4. paved the way for easy-care garments
     5. High resistance to insects, fungi., animals, as well as molds, mildew, rot many chemicals.
     6. Melts instead of burning.
    7. Good specific strength

Production of nylon :

Nylon are condensation copolymers formed by reacting equal parts of a diamine and a dicarboxylic acid, so that amides are formed at both ends of each monomer in a process analogous to polypeptide biopolymers. A compound has an acid at one end and an amine at the other and is polymerized to from a chain with repeating unites of  (-NH-[CH₂]_n-CO-)_x.

Tow molecules of water are given off and the nylon is formed. Its properties are determined by the R and R' groups in the monomers.

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Acetate Rayon and Acetate Fiber Properties

Properties of Cuprammonium Rayon :

1. Produce a soft silk like handle.

2. Have same properties as cotton except the average DP is lower, and a larger part of this fiber is occupied by amorphous region.

3. It burns rapidly and chars at 180 deg C.

4. On ignition, it leaves behind ash containing copper.

Production of Cuprammonium Rayon :

It is produced by making cellulose a soluble compound by combining it with copper and ammonia. The solution of this material in caustic soda is passed through the spinneret and cellulose is regenerated in the hardening baths that remove the copper and ammonia and neutralize the caustic soda.

The reactions involved are as follows :

NaOH (aq) + CuSO4 (aq) → Cu(OH)2 (s) + Na2SO4 (aq)
Cu(OH)2 (aq) → Cu2+ (aq) + 2 OH− (aq)
n Cu2+ (aq) + (cellulose)n + 2n OH− → (CuC6H8O5)n + 2n H2O

Acetate Rayon :

If the cellulose is treated with acetic acid under certain conditions the free hydroxyl groups of cellulose are converted into ester groups.

                          Alcohol + Acid  --------  Ester

Raw Material :

Cotton linters and wood pulp are the most common employed raw materials for the manufacture of acetate rayon.

Production Process of Acetate Fiber :

Acetate fiber is produced by reacting high purity wood pulp with acetic anhydride. The acetate flakes that are produced through this chemical reaction are dissolved in a solvent, filtered, and adjusted to obtain spinning stock solution. The spinning stock solution is extruded through controlled nozzles with extremely small  pore diameters ranging from 30 to 50μm. The solvent is then evaporated, and the yarns are formed. The cross section of acetate fiber is called a “chrysanthemum,” and is shaped uniquely with many lobes. After the spinning stock has been extruded through the pores, it takes on a round-shaped cross section.

However, rapid evaporation of the solvent from the surface results in the formation if a skin layer on the surface of the fiber. After that, evaporation of the solvent from the inside of the fiber causes the skin layer to cave in toward the fiber cross-section, giving rise to the final multi-location cross-section.


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Advantage & Disadvantage of Synthetic Fibers

Advantages of Synthetic Fiber : 

1. A great advantage of synthetic fibers is that they are more durable than most natural fibers. 

2. Many synthetic fibers offer consumer-friendly functions such as stretching, waterproofing and stain resistance.

3. Synthetic fibers are not a good source for these fabric-damaging insects.

4. Synthetic fibers do not break down easily when exposed to light, water, or oil.

5. Modern synthetic fabrics can look and as luxurious as silk or wool.

Disadvantages of Synthetic Fiber :

1. Synthetic fibers burn more readily than natural.

2. More electrostatic charge is generated by rubbing than with natural fibers. 

3. Prone to heat damage. Melt relatively easily.

4. Not skin friendly, so uncomfortable for long wearing.

5. Allergic to some people.

6. Non-biodegradable in comparison to natural fibers.

Viscose Rayon :

Viscose is both a semi-synthetic fabric formerly called viscose rayon or rayon and a solution of cellulose xanthate produced by treating dissolving pulp with aqueous sodium hydroxide and carbon dssulfide used to spin the viscose rayon fiber. Byproducts of the production process include sodium thiocarbonate, sodium carbonate, and sodium sulfide. Viscose rayon fiber is a soft fiber commonly used in dresses, linings, shirts, shorts, cats, jackets, and other outer wear, it is also used in industrial yarns, unholstery and carpets. It is also used in the casting of Cellophane.

Manufacture of Viscose Rayon :

Viscose rayon is a fiber of regenerated cellulose, it is structurally similar to cotton but may be produced from a variety of plants such as soy, bamboo, and suger cane, Cellulose is a linear polymer of β-D-glucose units with the empirical formula (C6H10O5)n. To prepare viscose, dissolving pulp is treated with aqueous sodim hydroxide (typically 16-19%w/w) to form "alkali cellulose," which has the approximate formula [C6H9O4-ONa]n. The alkali cellulose is then treated with carbon disulfide to form sodium cellulose xanthate.

                        [C6H9O4-ONa]n + nCS2 → [C6H9O4-OCS2Na]n

Rayon fiber is produced from the ripnened by treatment with a mineral acid, such as sulfuric acid. In this step, the xanthate groups are hydrolyzed to regenerate cellulose and release dithiocarbonic acid that later decomposes to carbon disulfide and water.

[C6H9O4-OCS2Na]2n + nH2SO4 → [C6H9O4-OH]2n +2nCS2 + nNa2SO4
                                      H2COS2 → H2O + CS2

Aside from regenerated cellulose, acidification given hydrogen sulfide, sulfur. and carbon disulfide. The thread made from the regenerated cellulose is washed to remove acid. The sulfur is then remoyed by the addition of sodium sulfide solution and impurities are oxidized by bleaching with sodium hypochlorite solution.

Wet-Dry-Melt-Gel Spinning Fibers Process Solutions

Wet Spinning :

Wet spinning is the oldest process. It is used for fiber-forming substances that have been dissolved in a solvent. The spinnerets are submerged in a chemical both and as the filaments emerge they precipitate from solution and solidify. Because the solution is extruded directly into the precipitating liquid, this process for making fibers is called wet spinning. Acrylic, rayon, aramid, modacrylic and spandex can be produced by process.

Dry Spinning :

Dry spinning is also used for fiber -forming is solution. However, instead of precipitating the polymer by dilution or chemical reaction., solidification is achieved by evaporating the solvent in a stream of air or inert gas.

The filaments do not come in contact with a precipitating liquid, eliminating the need the drying and easing solvent recovery. This process may be used for the production of acetate, triacetate, acrylic, modacrylic, PBI, spandex, and vinyon.

Melt Spinning :

In melt spinning, the fiber-forming substance is melted for extrusion through the spinneret and then directly solidified by cooling. Nylon, olefin, polyester, saran, and sulphur are produced in this manner. Melt spun fibers can be extruded from the spinneret in different cross-sectiona shapes ( round, trilobal, pentagonal, octagonal, and others ). Trilobal-shaped fibers reflect more light and give an attrative sparkle to textiles.

Gel Spinning :

Gel spinning is a special process used to obtain high strength or other special fiber properties. The polymer is not in a true liquid state during extrusion. Not completely separated as they would be in a true solution, the polymer chains are bound together at various points in liquid crystal form. This produces strong inter-chain forces in the resulting filaments that can significantly increase the tensile strength of the fibers. 

The filaments emerge with an unusually high degree of orientation relative to each other further enhancing strength. The process can also be described as dry-wet spinning, since the filaments first pass through air and then are cooled further in a liquid bath . Some high-strength polyethylene and aramid fibers are produced by gel spinning.

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The Manufacturing of Synthetic Fibers and Availability

Fineness of Staple :

A fiber must possess sufficient fineness of staple to be useful in the production of spun yarns. The principle fibers all have small diameters and a large number of them can be twisted together to yield a fine thread. Other things equal, the finer the staple of the fiber, the finer the yarn which can be produced form it. 

Porosity; Capillarity :

By this is meant that the fiber should be capable of easily adsorbing liquids and solutions and of permitting these thoroughly to permeate its substance. This property is important as it allows of the dyeing, bleaching, and otherwise preparing the fibers by modifying their natural condition.

Luster :

A further quality, which under certain conditions enhances the value of a textile fiber, is luster. Fiber possessing this quality to a marked degree, such as silk, mercerized cotton, and certain kinds of wool, are capable of producing a wide variety of beautiful effects.

Commercial Availability :

The second feature to which reference is made has principally an economic significance. In order to possess commercial value a fiber must be available in large quantity, and its supply must be more or less constant and readily marketed.

Synthetic Fiber :

Synthetic fibers or fibers are the result of extensive research by scientists to improve on naturally occurring animal and plant fibers. In general, synthetic fibers are created by forcing, usually through extrusion, fiber forming materials through holes (called spinnerets) into the air and water forming a thread. Before synthetic fibers were developed, artificially manufactured fibers were made from polymers obtained from petrol chemicals. These fibers are called synthetic fibers and and also called artificial fibers . Some of the fibers are made from plant cellulose. They are called as "cellulose fibers"

Manufacturing of Synthetic Fiber :

The fiber-forming polymers are solids and therefore must be first converted into a fluid state for extrusion. This is usually achieved by melting, if the polymers are thermoplastic synthetics. There are four methods of spinning filaments of manufactured fibers, wet, dry, melt, and gel spinning.

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Classification & Definition of Textile Fibers

Textile :

The definition of textile is something related to fabrics or the fabric industry. textile is defined as cloth or woven or knitted fabric.

A piece of heavy linen that you buy in order to sew a dress is in example of a textile.

Classification of Textile Fiber :

Generally two types of Textile fiber-

1. Natural fiber.

2. Man made fiber.

Natural Fiber :

Natural fiber include those produced by plants, animals and geological processes. They are biodegradable over time. They can be classified according to their origin. 

Example : Vegetable, Animal Cotton.

Man-made Fiber : 

Synthetic or man-made fibers generally come from synthetic materials such as petrochemicals. But some types of synthetic fibers are manufactured from natural cellulose, including rayon, model, and the more recently developed Lyocell. Cellulose-based fibers are of two types, regenerated or pure cellulose such as from the cupro-ammonium process and modified or derivatives cellulose such as the cellulose acetates. 

Examplie : Fiber glass.

Difference between Natural Fiber and Synthetic fiber : 

Natural Fiber	Synthetic Fiber
1. All the natural fiber comes from nature.	1. Synthetic fibers are completely man made.
2. Length of the fiber is nature given.	2. The length of fiber is controlled by men
3. Fibers are found in shape or filament form.	3. It is found in filament form but sometimes it could be converted into shape or cut length.
4. No need to spinneret for spinning process.	4. Spinneret is essential for filament production.
5. No need of chemical solution for yarn production.	5. Chemical solution is essential for yarn production.
6. Natural fabric is comfortable to wear.	6. Synthetic textile product is not as comfortable as natural product.

General Properties of Textile Fiber :

Tensile Strength :

There are a number of fibers, especially among the vegetable class ( such as those of the common milkweed, etc ). Which might prove of considerable value but for their lack of sufficient tensile strength. Although dependent also on other qualities, the resistance of a fiber to use and wear is primarily dependent on its tensile strength.

Length of Fiber :

The second important quality which determines the usefulness of a textile fiber is its length. Where a continuous thread is to be made up of a large number of individual elements, these elements must possess a considerable length with reference to their thickness, otherwise it would not be possible to make a thread that would hold together. In a general way and other conditions being equal, the strength of such a thread will be directly proportional to the length of the individual fiber elements employed.

Cohesiveness :

A third essential quality for a textile fiber is cohesiveness. By this is meant the property of the individual fibers cohering or holding on to one another when spun into a yarn. This is usually brought about by the surface of the surface of the fibers possessing a high degree of frictional resistance.

Pliability; Elasticity :

Another quality which is very essential to a satisfactory textile fiber is pliability, which permits of one fiber being easily wrapped around another in the spinning operation. The pliability of a fiber also determines on great measure its elasticity and resiliency, qualities which are often of prime importance in the manufacture of textile fabrics. Lack of these properties will make the fiber and its resulting products brittle and unyielding, and hence greatly limit the field of its usefulness.

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