BY: SUMAIR IQBAL

(TS-1A)

ASSIGNMENT ONPOLYESTER

DEFINATION

Polyester (aka Terylene) is a category of polymers which contain the ester functional group in their main chain.

“Long chain polymers chemically composed of at least 85% by weight of an ester and a dihydric alcohol and terephthalic acid”. The name “polyester” refers to the linkage of several monomers (esters) within the fiber.

HISTORY

In 1926, United States-based E.I. du Pont de Nemours and Co. began research into very large molecules and synthetic fibers

W.H. Carothers, centered on what became nylon, the first synthetic fiber. 1939-41, British research chemists took interest in the du Pont studies and

conducted their own research in the laboratories of Calico Printers Association, Ltd. This work resulted in the creation of the polyester fiber known in England as Terylene.

In 1946, du Pont purchased the right to produce this polyester fiber in the United States.

The company conducted some further developmental work, and in 1951, began to market the fiber under the name Dacron

FORMS OF POLYESTER

1. Filament

2. Staple

3. Tow

4. Fiberfill

Uses Of Different Form In Different Places

1. In the filament form, each individual strand of polyester fiber is continuous in length, producing smooth-surfaced fabrics

2. In staple form, filaments are cut to short, predetermined lengths. In this form polyester is easier to blend with other fibers

3. Tow is a form in which continuous filaments are drawn loosely together

4. Fiberfill is the voluminous form used in the manufacture of quilts, pillows, and outerwear

Microscopic View

Different Structures Of Polyester

STRUCTURE AND APPERANCE

COLOURLESS AND TRANSPARENTSMOOTH AND LUSTURUOSSHAPE AS WE REQIURESHINY GLASSROD LIKE

Polyester Fiber Characteristics

Strong Resistant to stretching and shrinking Resistant to most chemicals Quick drying Crisp and resilient when wet or dry Wrinkle resistant Mildew resistant Abrasion resistant Retains heat-set pleats and crease Easily washed

DISTINGUISHING FORM OTHERS

DISTINGUISHING POLYESTERS FROM OTHER FIBERS:Polyester is soluble in hot meta cresol; however ,unlike acetate it is not soluble in acetone,

and unlike nylon it is not soluble in concentrated formic acid.

Polyester Blends

Polyester and Cotton1. Resist wrinkles2. Resist stains3. Retain shape

Polyester Blends

Polyester and Wool1. Wrinkle resistance2. Shape retention3. Increase durability

Polyester Blends

Polyester and Rayon1. More durable2. Shape retention3. More resilience

Manufacturing Filament Yarn

PolymerizationDryingMelt spinningDrawing the fiberWinding

Polymerization To form polyester, dimethyl terephthalate is first reacted with ethylene glycol in the

presence of a catalyst at a temperature of 302-410°F (150-210°C). The resulting chemical, a monomer (single, non-repeating molecule) alcohol, is

combined with terephthalic acid and raised to a temperature of 472°F (280°C). Newly-formed polyester, which is clear and molten, is extruded through a slot to form long ribbons.

Drying PET polyester fabrics are readily dried at 120˚C. and are normally handled on pin or

clip sentres. Care must be taken to ensure that the fabric is not stentered under heavy tension. If it is necessary to remove scouring creases, the damp fabric should be stentered out, without overfeed, to a width which exceeds the scoured width by 7-14 mm per m (¼-½ in. per yd.), and then drier at 140-150˚C. Relaxed drying methods are preferred for caustic soda softened fabrics and some yarn dyed fabrics.

Melt spinning

Polymer chips are melted at 500-518°F (260-270°C) to form a syrup-like solution. The solution is put in a metal container called a spinneret and forced through its tiny holes, which are usually round, but may be pentagonal or any other shape to produce special fibers. The number of holes in the spinneret determines the size of the yarn, as the emerging fibers are brought together to form a single strand.

At the spinning stage, other chemicals may be added to the solution to make the resulting material flame retardant, antistatic, or easier to dye.

Drawing the fiber When polyester emerges from the spinneret, it is soft and easily

elongated up to five times its original length. This increases the strength, tenacity, and resilience of the fiber. This time, when the filaments dry, the fibers become solid and strong instead of brittle.

Drawn fibers may vary greatly in diameter and length, Also, as the fibers are drawn, they may be textured or twisted to create softer or duller

fabrics.

Winding After the polyester yarn is drawn, it is wound on large bobbins or flat-

wound packages, ready to be woven into material.

Properties

Denier: 0.5 – 15 Tenacity : dry 3.5 - 7.0 : wet 3.5

- 7.0 Elongation at break : dry 15 - 45 : wet 15 45% Moisture Regain: 0.2-0.5% Specific Gravity: 1.36 - 1.41% Elastic Recovery : @2% =98 : @5% = 65 Melting point : 260 - 270 degree C Effect of Sunlight : turns yellow, retains

70 - 80 % tenacity at long exposure Resistance to Weathering: good Rot Resistance: high Alkali Resistance: damaged by CON alkali Acid Resistance: excellent Insects: no effect

General Properties of Fiber

Filament Yarn Staple and tow

Property Regular tenacity

High tenacity

Regular tenacity

High tenacity

breaking tenacity, N/tex

0.35-0.5 0.62-0.85 0.35-0.47 0.48-0.61

breaking elongation

24-50 10-20 35-60 17-40

elastic recovery at 5% elongation, %

88-93 90 75-85 75-85

initial modulus, N/tex

6.6-8.8 10.2-10.6 2.2-3.5 4.0-4.9

specific gravity 1.38 1.39 1.38 1.38

Moisture regain, % 0.4 0.4 0.4 0.4

Melting temperature, o C

258-263 258-263 258-263 258-263

Chemistry of Polyester fiber

COOHHOOC + CH3OH COOCH3CH3OOC

COOCH3CH3OOC + HOCH2CH2OH

COOCH2CH2OHHOCH2CH2OOC CH3OH+

Terephthalic Acid Dimethyl Terephthalate

Bis(2-Hydroxyethyl) Terephthlate

Polyester

Ethylene Glycol

C

O

COCH2CH2O

O

C

O

OCH2CH2OC

O

Polymerization

n

Other Properties Of Polyester

Fineness of polyester textile: Fineness of polyester fiber is also controllable. X-Sectional shape: Normal cross sectional shape is round but it is also made triangular, elliptical or pentagonal. Normally it is white but could be of any color if color is added during spinning.

Extensibility: Extension at break varies from 20% to 30 %. Good recovery from extension. Due to good extension, strength and functional property polyester is widely used as sewing thread in the garment industries.

Resiliency: Polyester textile shows good resiliency property. It does not crease easily and any undue crease can be recovered easily.

Dimensional Stability: Polyester fiber is dimensionally stable. It could be heat-set at around 200 degree C. heat set polyester fiber does not shrink or extended. Action of bleaching agents: It is not damaged by the action of bleaching agents.

Action of acid and alkali: It is unaffected by the action of acid and alkali.

Action of organic solvent: Polyester textile is unaffected by organic solvent, hence polyester fiber could be dry-cleaned.

Demand For Polyester

DYEING

Polyester fibres are hydrophobic, and dyeing of useful depth are obtained by using those classes of dyestuffs which are substantially insoluble in water. These include the disperse dyestuffs, azoic dyestuffs (applied by a modified technique), and a limited number of vat dyes.

PRINTING

Fabrics woven from 100% PET polyester fibre yarn are usually printed with disperse dyestuffs, although a limited number of vat dyestuff may be used. The disperse dye provide a wide range of bright and deep shades, but the choice of individual dyestuffs is governed not only by the projected end-use, but also by the method to be used in fixing the color on to the fibre.

FUTURE

Biodegradable and biocompatible poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), a copolymer of microbial polyester, was fabricated as a Nano fibrous mat by electro spinning

The researchers have developed a process in which polyester is dramatically strengthened with a material known as a liquid crystalline polymer. The liquid crystalline polymer used in the research is called Vectra , a plastic material similar to Kevlar that is five times stronger than steel. Polyester is used because its chemical structure is ideal for making bonds with the liquid crystalline polymer

Some Major Polyester Fiber Uses

Apparel: Every form of clothing Home Furnishings: Carpets, curtains,

draperies, sheets and pillow cases, wall coverings, and upholstery

Other Uses: hoses, power belting, ropes and nets, thread, tire cord, auto upholstery, sails, floppy disk liners, and fiberfill for various products including pillows and furniture

Care of your polyester garment:

1. Machine-wash your fabric in cold water.

2. Wash with light colors.

3. Use a gentle cycle while washing.

4. Tumble dry with the setting low.

5. Do not bleach.

6. If needed, iron with a cool iron.