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

To be continue.....

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.

To be continue........

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.

To be Continue........

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.


To be continue......