Polyester began as a group of polymers in W.H. Carothers' laboratory. Carothers was working for DuPont at the time when he discovered that alcohols and carboxyl acids could be successfully combined to form fibers. Polyester was put on the back burner, however, once Carothers discovered nylon. A group of British scientists--J.R. Whinfield, J.T. Dickson, W.K. Birtwhistle, and C.G. Ritchie--took up Carothers' work in 1939. In 1941 they created the first polyester fiber called Terylene. In 1946 DuPont bought all legal rights from the Brits and came up with another polyester fiber which they named Dacron.

In 1958 another polyester fiber called Kodel was developed by Eastman Chemical Products, Inc. The polyester market kept expanding. Since it was such an inexpensive and durable fiber, many small textile mills emerged all over the country--many located in old gas stations--to produce cheap polyester apparel items. Polyester experienced a constant growth until the 1970s when sales drastically declined due to the negative public image that emerged in the late 60s as a result of the infamous polyester double-knit fabric!

Today, polyester is still widely regarded as a "cheap, uncomfortable" fiber, but even now this image is slowly beginning to change with the emergence of polyester luxury fibers such as polyester micro fiber.

Polyester is currently defined as: "Long-chain polymers chemically composed of at least 85 percent by weight of an ester and a di-hydric alcohol and a terephthalic acid." The name "polyester" refers to the linkage of several monomers (esters) within the fiber. Esters are formed when alcohol reacts with a carboxylic acid.

There are many possible variations of the generic polyester fiber. Two that are currently produced commercially are polyethylene terephthalate (PET) and poly-1,4, cyclohexylene dimethylene (PCDT). A third polyester fiber, polyethylene oxybenzoate (PEB) was manufactured in Japan during the 1970s and early 1980s under the trade name A-Tell®. Production of this fiber was discontinued, because it did not offer enough performance advantages to remain competitive in the textile market.

• 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
• able to retain heat-set pleats and creases
• easily washed

Because of their many desirable qualities, polyester fibers and fabrics have many uses.

Polyester is often used in outerwear because of its high tenacity and durability. It is a strong fiber and consequently can withstand strong and repetitive movements. Its hydrophobic property makes it ideal for garments and jackets that are to be used in wet or damp environments - coating the fabric with a water-resistant finish intensifies this effect.

Many jackets and quilted garments are made of polyester. Since polyester can be molded into almost any shape, certain insulating properties can be built-in to the fiber. One method is to create hollow fibers: 

This process traps air inside the fiber which is then heated by the body. The warm air stays inside and helps warm the body in cool weather. A second method is to use crimped polyester in a fiberfill product. The crimp helps to keep in warm air. Polyester is an ideal fiber to use for this since it will retain its shape, unlike its cotton and wool counterparts that tend to flatten out over time, significantly reducing their ability to trap warm air.

Polyester is used in pants, shirts, suits, and bed sheets either by itself or as a blend, because of its wrinkle-resistant property and its ability to retain its shape. Since these garments are frequently worn and washed, its stain-resistance and durability are also desirable.

Polyester also has industrial uses as well, such as carpets, filters, synthetic artery replacements, ropes, and films. 

• POY yarns
• flat yarn
• textured yarn
• airtextured yarn 
• high tenacity
• monofilament
• staple fibers
• cut flock 
• tow
• spun yarns

Most polyesters are made from petroleum from which the constituent acids and alcohols are derived. The types of processes that manufacturers use vary, and little is known about specific manufacturing processes, because the companies want to keep them a secret in order to remain competitive. Here is a general description of how polyester is synthesized: 

1) Polymerization
Condensation polymerization occurs when the acid and alcohol are reacted in a vacuum at high temperatures. The polymerized material is extruded in the form of a ribbon onto a casting trough or cooling wheel. After the ribbon hardens, it is cut into chips.

2) Spinning
The chips are dried and then put into hopper reservoirs for melting. Polyester is a "melt spun" fiber, which means that it is heated, extruded through the spinnerets, and cools upon hitting the air. From there it is wound around cylinders.

3) Drawing
The fibers are then hot stretched until they are about five times their original length in order to decrease their width. The drawing results in a optimal orientation of the molecules inside the fiber and results in a perfect strength.

Variations on the Basic Polyester

Different fibers can be created by doing one or more of the following:

1. Adding a delusterant (dulling agent) - 
   Polyester is a naturally bright fiber, but can be made dull or semi-dull by the addition of a TiO2.
   
2. Changing the shape of the holes in the spinneret
   The simplest and most common shape is a circle, but by changing the shape of the spinneret, square, oval, and bean-shaped fibers can be formed. One can even create a hollow fiber. The different shapes affect the hand and strength of the fiber.
   
3. Drawing it out more
   Drawing out the fiber to five times its original length is normal, but polyester can be stretched even further. Drawing it out more than normal may also affect the strength, elasticity, and dye-ability.
   
4. Adding dye stuffs
   In its natural state, polyester is a slightly transparent off-white. Adding dye stuffs at the manufacturing stage can create brilliant colors like electric blue and atomic red. In this field Setila is one of the World leader with its DECORA programme, especially for the automotive industry where extremely high fastness requirements are demanded
   
5. Crimping
   When the fiber is drawn out it is long and smooth. Crimping can give the fiber more texture and bulk and can increase its insulation properties, as well as its elasticity. Another word for this is texturizing.

Making Yarns

After the fiber itself is created, it is made into a yarn. There are two types of polyester yarns: filament and spun. 

Filament yarns are made by taking the single polyester filaments, grouping them together and then twisting or air-entangling them to make them workable. A monofilament yarn has just one, single polyester fiber that is usually not twisted.

Spun yarns are produced in much the same way as a cotton or wool yarn is produced. The long filaments are fist cut into short pieces called staple. These are then combined together and spun to create a yarn made up of thousands of short filaments.

Blends

At this stage, polyester can also be combined with other fibers to produce a variety of effects.
Polyester and cotton is probably the most famous and popular blend. The polyester helps the fabric retain its shape and resist stains and wrinkles. The cotton makes the fabric more absorbent and comfortable.

Polyester is combined with wool to give it wrinkle-resistance and shape retention in all kinds of weather. Since polyester is stronger than wool, it increases the durability and life of the fabric. The wool contributes good draping characteristics and elasticity.

Polyester and rayon is another popular blend fabric. Here again the polyester makes the fabric more resilient and durable, and helps it keep its shape. The rayon adds a different texture, has a good hand, is good for draping, and is more absorbent.

Polyester and nylon produce a strong fabric because of nylon's strength and abrasion resistance and polyester's wrinkle-free properties. This combination produces a yarn that is strong, durable, stable, easy to launder, and resistant to mildew and insects. Problems with this blend, however, are that pilling may occur, and it does not have a very nice hand. Furthermore, since neither nylon nor polyester is very absorbent, the fabric may feel wet and clammy in warm or humid weather.

Weaving

After the yarns are made, they are shipped out to textile mills to be woven into fabric. Polyester can be made into both woven and knitted fabrics (such as the infamous double-knit!)

Finishing Processes

Finally, after the fabric is made, one or more of the following finishing processes is often used to improve the quality of the fabric: 

• Heat setting--creates a permanent shape 
• Singeing--improves the hand, reduces pilling, and increases smoothness 
• Anti-static finish--reduces static electricity 
• Water and stain repellency--increases comfort and makes it easier to clean; also used for rainwear 
• Resin finishes--increases ease of care 
• Calendaring--increases smoothness and reduces pilling 
• Embossing--creates a design and/or luster 

• in flat filament yarn
• In POY yarn
• in friction textured yarn
• in airtextured yarn
• in high tenacity yarn
• in monofilament
• in staple fiber
• in spun yarn
• in cut flock