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polyester

 
(pŏl'ē-ĕs'tər, pŏl'ē-ĕs'tər) pronunciation
n.
  1. Any of numerous synthetic polymers produced chiefly by reaction of dibasic acids with dihydric alcohols and used primarily as light, strong, weather-resistant resins in boat hulls, textile fibers, adhesives, and molded parts.
  2. A wrinkle-resistant fabric of fibers made from any of these resins.
polyester pol'y·es'ter adj.
polyesterification pol'y·es'ter·i·fi·ca'tion (-ə-fĭ-kā'shən) n.

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Organic compound, any of a class of polymers formed by ester linkages between monomers. They are usually prepared from equivalent amounts of glycols and dibasic carboxylic acids, which undergo condensation polymerization to produce the polyester and water. Polyesters are strong, colourfast, and resistant to corrosion and chemical attack but tend to build up a static electric charge. In addition to the familiar fibres and films (e.g., Dacron, Mylar), polyesters are used to make reinforced plastics, automotive parts, boat hulls, foams, laminates, tapes, piping, bottles, disposable filters, encapsulations, and coatings.

For more information on polyester, visit Britannica.com.

Gale's How Products Are Made:

How is polyester made?

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Background

Polyester is a synthetic fiber derived from coal, air, water, and petroleum. Developed in a 20th-century laboratory, polyester fibers are formed from a chemical reaction between an acid and alcohol. In this reaction, two or more molecules combine to make a large molecule whose structure repeats throughout its length. Polyester fibers can form very iong molecules that are very stable and strong.

Polyester is used in the manufacture of many products, including clothing, home furnishings, industrial fabrics, computer and recording tapes, and electrical insulation. Polyester has several advantages over traditional fabrics such as cotton. It does not absorb moisture, but does absorb oil; this quality makes polyester the perfect fabric for the application of water-, soil-, and fire-resistant finishes. Its low absorbency also makes it naturally resistant to stains. Polyester clothing can be preshrunk in the finishing process, and thereafter the fabric resists shrinking and will not stretch out of shape. The fabric is easily dyeable, and not damaged by mildew. Textured polyester fibers are an effective, nonallergenic insulator, so the material is used for filling pillows, quilting, outerwear, and sleeping bags.

History

In 1926, United States-based E.I. du Pont de Nemours and Co. began research into very large molecules and synthetic fibers. This early research, headed by W.H. Carothers, centered on what became nylon, the first synthetic fiber. Soon after, in the years 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. During the ensuing years, several companies became interested in polyester fibers and produced their own versions of the product for different uses. Today, there are two primary types of polyester, PET (polyethylene terephthalate) and PCDT (poly-1, 4-cyclohexylene-dimethylene terephthalate). PET, the more popular type, is applicable to a wider variety of uses. It is stronger than PCDT, though PCDT is more elastic and resilient. PCDT is suited to the heavier consumer uses, such as draperies and furniture coverings. PET can be used alone or blended with other fabrics to make clothing that is wrinkle and stain resistant and retains its shape.

Raw Materials

Polyester is a chemical term which can be broken into poly, meaning many, and ester, a basic organic chemical compound. The principle ingredient used in the manufacture of polyester is ethylene, which is derived from petroleum. In this process, ethylene is the polymer, the chemical building block of polyester, and the chemical process that produces the finished polyester is called polymerization.

The Manufacturing
Process

Polyester is manufactured by one of several methods. The one used depends on the form the finished polyester will take. The four basic forms are filament, staple, tow, and fiberfill. In the filament form, each individual strand of polyester fiber is continuous in length, producing smooth-surfaced fabrics. In staple form, filaments are cut to short, predetermined lengths. In this form polyester is easier to blend with other fibers. Tow is a form in which continuous filaments are drawn loosely together. Fiberfill is the voluminous form used in the manufacture of quilts, pillows, and outerwear. The two forms used most frequently are filament and staple.

Manufacturing Filament Yarn

Polymerization

Drying

  • After the polyester emerges from polymerization, the long molten ribbons are allowed to cool until they become brittle. The material is cut into tiny chips and completely dried to prevent irregularities in consistency.

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. The stretching forces the random polyester molecules to align in a parallel formation. 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, depending on the characteristics desired of the finished material. 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.

Manufacturing Staple Fiber

In making polyester staple fiber, polymerization, drying, and melt spinning (steps 1-4 above) are much the same as in the manufacture of filament yarn. However, in the melt spinning process, the spinneret has many more holes when the product is staple fiber. The rope-like bundles of polyester that emerge are called tow.

Drawing tow

  • Newly-formed tow is quickly cooled in cans that gather the thick fibers. Several lengths of tow are gathered and then drawn on heated rollers to three or four times their original length.

Crimping

  • Drawn tow is then fed into compression boxes, which force the fibers to fold like an accordion, at a rate of 9-15 crimps per inch (3-6 per cm). This process helps the fiber hold together during the later manufacturing stages.

Setting

  • After the tow is crimped, it is heated at 212-302°F (100-150°C) to completely dry the fibers and set the crimp. Some of the crimp will unavoidably be pulled out of the fibers during the following processes.

Cutting

  • Following heat setting, tow is cut into shorter lengths. Polyester that will be blended with cotton is cut in 1.25-1.50 inch (3.2-3.8 cm) pieces; for rayon blends, 2 inch (5 cm) lengths are cut. For heavier fabrics, such as carpet, polyester filaments are cut into 6 inch (15 cm) lengths.

The Future

Following its introduction to the United States in 1951, polyester quickly became the country's fastest-growing fiber. Easy care of the permanent press fabric made polyester doubleknits extremely popular in the late 1960s. However, polyester has suffered an "image problem" since that time, and clothes made out of polyester were often devalued and even ridiculed. Several new forms of polyester introduced in the early 1990s may help revitalize the image of polyester. A new form of polyester fiber, called microfiber, was introduced to the public in 1991. More luxurious and versatile than traditional polyester, microfiber fabrics are difficult to tell apart from silk fabrics. Clothing designers such as Mary McFadden have created a line of clothes using this new form of polyester. Textile researchers at North Carolina State University are developing a form of polyester that may be as strong as Kevlar, a superfiber material used to make bulletproof vests. This type of polyester may eventually be used as composite materials for cars and airplanes.

Where To Learn More

Books

Corbman, Bernard P. Textiles: Fiber to Fabric. 6th ed. Gregg Division, McGraw-Hill, 1983, pp. 374-92.

Encyclopedia of Textiles. 3rd ed. Prentice-Hall, Inc., 1980, pp. 28-33.

Polyester: Fifty Years of Achievement. State Mutual Book & Periodical Service, 1993.

Periodicals

Fellingham, Christine. "Will You Learn to Love Polyester?" Glamour, April 1992, p. 204.

Templeton, Fleur. "Show Me a Bulletproof Leisure Suit, In Pink." Business Week, July 6, 1992, p. 65.

Thomas, Marita. "At 50 Years, Polyester Gains New Fashion Vitality." Textile World, December 1993, p. 62+.

[Article by: Kristine M. Krapp]


Columbia Encyclopedia:

polyester

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polyester, synthetic fiber, produced by the polymerization of the product formed when an alcohol and organic acid react. The outstanding characteristic of polyesters is their ability to resist wrinkling and to spring back into shape when creased. In addition, polyesters have good dimensional stability, wash and dry easily and quickly, and have excellent wash-and-wear or minimum-care characteristics; one of their principal uses is in apparel fabrics of this kind. Microfiber, which was introduced in 1986, is a variety of polyester that has extremely thin filaments (half as thick as silk fibers). Polyesters are also used in casement curtains, throw rugs, and as a cushioning or insulating material.


Word Tutor:

polyester

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pronunciation

IN BRIEF: An artificial resin used in making plastics and fibers for fabrics.

pronunciation Do you prefer cotton or polyester shirts?

LearnThatWord.com is a free vocabulary and spelling program where you only pay for results!


any synthetic polymer in which the constitutional units are joined by ester bonds; proprietary materials include Dacron and Mylar. Polyesters are extensively used in textiles, ropes, etc.

Previous:polyenoic acid, polyene antibiotic, polyene
Next:polyethylene, polyethylene glycol, polyfructosan

A multifilament strand of synthetic polymer.

  • p. base — the film on which the photographic emulsion is added to make an x-ray plate.
  • p. mesh — see surgical mesh.
  • p. suture — a multifilament strand, Dacron impregnated or coated with Teflon, silicone or polybutylate used as nonabsorbable sutures. Their virtue is their strength, their disadvantage the difficulty encountered in tying a knot that holds.
Random House Word Menu:

categories related to 'polyester'

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Random House Word Menu by Stephen Glazier
For a list of words related to polyester, see:

SEM picture of a bend in a high-surface area polyester fiber with a seven-lobed cross section
Close-up of a polyester shirt
Supermacro closeup of a speaker cover fabric

Polyester is a category of polymers which contain the ester functional group in their main chain. Although there are many polyesters, the term "polyester" as a specific material most commonly refers to polyethylene terephthalate (PET). Polyesters include naturally occurring chemicals, such as in the cutin of plant cuticles, as well as synthetics through step-growth polymerization such as polycarbonate and polybutyrate. Natural polyesters and a few synthetic ones are biodegradable, but most synthetic polyesters are not.

Depending on the chemical structure, polyester can be a thermoplastic or thermoset; however, the most common polyesters are thermoplastics.[1]

Fabrics woven or knitted from polyester thread or yarn are used extensively in apparel and home furnishings, from shirts and pants to jackets and hats, bed sheets, blankets, upholstered furniture and computer mouse mats. Industrial polyester fibers, yarns and ropes are used in tyre reinforcements, fabrics for conveyor belts, safety belts, coated fabrics and plastic reinforcements with high-energy absorption. Polyester fiber is used as cushioning and insulating material in pillows, comforters and upholstery padding. 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. Polyesters are widely used as a finish on high-quality wood products such as guitars, pianos and vehicle/yacht interiors. Thixotropic properties of spray-applicable polyesters make them ideal for use on open-grain timbers, as they can quickly fill wood grain, with a high-build film thickness per coat. Cured polyesters can be sanded and polished to a high-gloss, durable finish.

While synthetic clothing in general is perceived by many as having a less natural feel compared to fabrics woven from natural fibres (such as cotton and wool), polyester fabrics can provide specific advantages over natural fabrics, such as improved wrinkle resistance, durability and high color retention. As a result, polyester fibres are sometimes spun together with natural fibres to produce a cloth with blended properties. Synthetic fibres also can create materials with superior water, wind and environmental resistance compared to plant-derived fibres.

Liquid crystalline polyesters are among the first industrially used liquid crystal polymers. They are used for their mechanical properties and heat-resistance. These traits are also important in their application as an abradable seal in jet engines.

Contents

Types

Polyesters as thermoplastics may change shape after the application of heat. While combustible at high temperatures, polyesters tend to shrink away from flames and self-extinguish upon ignition. Polyester fibres have high tenacity and E-modulus as well as low water absorption and minimal shrinkage in comparison with other industrial fibres.

Unsaturated polyesters (UPR) are thermosetting resins. They are used as casting materials, fiberglass laminating resins and non-metallic auto-body fillers. Fibreglass-reinforced unsaturated polyesters find wide application in bodies of yachts and as body parts of cars.

According to the composition of their main chain, polyesters can be:

Composition of the main chain Number of repeating units Examples of polyesters Examples of manufacturing methods
Aliphatic Homopolymer Polyglycolide or Polyglycolic acid (PGA) Polycondensation of glycolic acid
Polylactic acid (PLA) Ring-opening polymerization of lactide
Polycaprolactone (PCL) Ring-opening polymerization of caprolactone
Copolymer Polyethylene adipate (PEA)
Polyhydroxyalkanoate (PHA)
Semi-aromatic Copolymer Polyethylene terephthalate (PET) Polycondensation of terephthalic acid with ethylene glycol
Polybutylene terephthalate (PBT) Polycondensation of terephthalic acid with 1,4-butanediol
Polytrimethylene terephthalate (PTT) Polycondensation of terephthalic acid with 1,3-propanediol
Polyethylene naphthalate (PEN) Polycondensation of at least one naphthalene dicarboxylic acid with ethylene glycol
Aromatic Copolymer Vectran Polycondensation of 4-hydroxybenzoic acid and 6-hydroxynaphthalene-2-carboxylic acid

Increasing the aromatic parts of polyesters increases their glass transition temperature, melting temperature, thermal stability, chemical stability...

Polyesters can also be telechelic oligomers like the polycaprolactone diol (PCL) and the polyethylene adipate diol (PEA). They are then used as prepolymers.

Industry

Basics

Polyester is a synthetic polymer made of purified terephthalic acid (PTA) or its dimethyl ester dimethyl terephthalate (DMT) and monoethylene glycol (MEG). With 18% market share of all plastic materials produced, it ranges third after polyethylene (33.5%) and polypropylene (19.5%).

The main raw materials are described as follows:

  • Purified terephthalic acid – PTA – CAS-No.: 100-21-0
Synonym: 1,4 benzenedicarboxylic acid,
Sum formula; C6H4(COOH)2 , mol weight: 166.13
  • Dimethylterephthalate – DMT – CAS-No: 120-61-6
Synonym: 1,4 benzenedicarboxylic acid dimethyl ester
Sum formula C6H4(COOCH3)2 , mol weight: 194.19
  • Mono Ethylene Glycol – MEG – CAS No.: 107-21-1
Synonym: 1,2 ethanediol
Sum formula: C2H6O2 , mol weight: 62,07

To make a polymer of high molecular weight a catalyst is needed. The most common catalyst is antimony trioxide (or antimony tri acetate):

Antimony trioxide – ATO – CAS-No.: 1309-64-4 Molecular weight: 291.51 Sum formula: Sb2O3

In 2008, about 10,000 tonnes Sb2O3 were used to produce around 49 million tonnes polyethylene terephthalate.

Polyester is described as follows:

Polyethylene Terephthalate CAS-No.: 25038-59-9 Synonym/abbreviations: polyester, PET, PES Sum Formula: H-[C10H8O4]-n=60–120 OH, molelcular unit weight: 192.17

There are several reasons for the importance of Polyester:

  • The relatively easy accessible raw materials PTA or DMT and MEG
  • The very well understood and described simple chemical process of polyester synthesis
  • The low toxicity level of all raw materials and side products during polyester production and processing
  • The possibility to produce PET in a closed loop at low emissions to the environment
  • The outstanding mechanical and chemical properties of polyester
  • The recyclability
  • The wide variety of intermediate and final products made of polyester.

In table 1 the estimated world polyester production is shown. Main applications are textile polyester, bottle polyester resin, film polyester mainly for packaging and specialty polyesters for engineering plastics. According to this table, the world's total polyester production might exceed 50 million tons per annum before the year 2010.

Table 1: World polyester production

Market size per year
Product type 2002 [Million tonnes/year] 2008 [Million tonnes/year]
Textile-PET 20 39
Resin, bottle/A-PET 9 16
Film-PET 1.2 1.5
Special polyester 1 2.5
Total 31.2 49

Raw material producer

The raw materials PTA, DMT, and MEG are mainly produced by large chemical companies which are sometimes integrated down to the crude oil refinery where p-Xylene is the base material to produce PTA and liquefied petroleum gas (LPG) is the base material to produce MEG.[citation needed]

Polyester processing

After the first stage of polymer production in the melt phase, the product stream divides into two different application areas which are mainly textile applications and packaging applications. In figure 2 the main applications of textile and packaging polyester are listed.

Table 2: Textile and packaging polyester application list

Polyester-based polymer (melt or pellet)
Textile Packaging
Staple fiber (PSF) Bottles for CSD, Water, Beer, Juice, Detergents
Filaments POY, DTY, FDY A-PET Film
Technical yarn and tire cord Thermoforming
Non-woven and spunbond BO-PET Biaxial oriented Film
Mono-filament Strapping

Abbreviations: PSF = Polyester Staple Fiber; POY = Partially Oriented Yarn; DTY = Draw Textured Yarn; FDY = Fully Drawn Yarn; CSD = Carbonated Soft Drink; A-PET = Amorphous Polyester Film; BO-PET = Biaxial Oriented Polyester Film;

A comparable small market segment (much less than 1 million tonnes/year) of polyester is used to produce engineering plastics and masterbatch.

In order to produce the polyester melt with a high efficiency, high-output processing steps like staple fiber (50–300 tonnes/day per spinning line) or POY /FDY (up to 600 tonnes/day split into about 10 spinning machines) are meanwhile more and more vertically integrated direct processes. This means the polymer melt is directly converted into the textile fibers or filaments without the common step of pelletizing. We are talking about full vertical integration when polyester is produced at one site starting from crude oil or distillation products in the chain oil → benzene → PX → PTA → PET melt → fiber/filament or bottle-grade resin. Such integrated processes are meanwhile established in more or less interrupted processes at one production site. Eastman Chemicals were the first to introduce the idea of closing the chain from PX to PET resin with their so-called INTEGREX process. The capacity of such vertically integrated production sites is >1000 tonnes/day and can easily reach 2500 tonnes/day.

Besides the above mentioned large processing units to produce staple fiber or yarns, there are ten thousands of small and very small processing plants, so that one can estimate that polyester is processed and recycled in more than 10 000 plants around the globe. This is without counting all the companies involved in the supply industry, beginning with engineering and processing machines and ending with special additives, stabilizers and colors. This is a gigantic industry complex and it is still growing by 4–8% per annum, depending on the world region. Useful information about the polyester industry can be found under [2] where a “Who is Producing What in the Polyester Industry” is gradually being developed.

Synthesis

Synthesis of polyesters is generally achieved by a polycondensation reaction. See "condensation reactions in polymer chemistry". 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

Azeotrope esterification

In this classical method, an alcohol and a carboxylic acid react to form a carboxylic ester. To assemble a polymer, the water formed by the reaction must be continually removed by azeotrope distillation.

Alcoholic transesterification

Transesterification: An alcohol-terminated oligomer and an ester-terminated oligomer condense to form an ester linkage, with loss of an alcohol. R and R' are the two oligomer chains, R'' is a sacrificial unit such as a methyl group (methanol is the byproduct of the esterification reaction).

Acylation (HCl method)

The acid begins as an acid chloride, and thus the polycondensation proceeds with emission of hydrochloric acid (HCl) instead of water. This method can be carried out in solution or as an enamel.

Silyl method
In this variant of the HCl method, the carboxylic acid chloride is converted with the trimethyl silyl ether of the alcohol component and production of trimethyl silyl chloride is obtained

Acetate method (esterification)

Silyl acetate method

Ring-opening polymerization

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.

Cross-linking

Unsaturated polyesters are thermosetting resins. They are generally copolymers prepared by polymerizing one or more diol with saturated and unsaturated dicarboxylic acids (maleic acid, fumaric acid...) or their anhydrides. The double bond of unsaturated polyesters reacts with a vinyl monomer mainly the styrene, resulting in a 3-D cross-linked structure. This structure acts as a thermoset. The cross-linking is initiated through an exothermic reaction involving an organic peroxide, such as methyl ethyl ketone peroxide or benzoyl peroxide.

See also

References

Further reading

  • Textiles, by Sara Kadolph and Anna Langford. 8th Edition, 1998.

External links


Translations:

Polyester

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Dansk (Danish)
n. - polyester

Nederlands (Dutch)
polyester

Français (French)
n. - polyester

Deutsch (German)
n. - Polyester

Ελληνική (Greek)
n. - (χημ.) πολυεστέρας

Italiano (Italian)
poliestere

Português (Portuguese)
n. - poliéster (m)

Русский (Russian)
полиэстер

Español (Spanish)
n. - poliéster

Svenska (Swedish)
n. - polyester, esterplast

中文(简体)(Chinese (Simplified))
多元酯

中文(繁體)(Chinese (Traditional))
n. - 多元酯

한국어 (Korean)
n. - 폴레에스테르

日本語 (Japanese)
n. - ポリエステル

العربيه (Arabic)
‏(الاسم) قماش اصطناعي‏

עברית (Hebrew)
n. - ‮בד עשוי סיבים מלאכותיים מפולימרים, פוליאסטר (אריג)‬


 
 

 

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