Polyestera class of synthetic polymers built up from multiple chemical repeating units linked together by ester CO-O groups. Polyesters display a wide array of properties and practical applications. Permanent-press fabrics, disposable soft-drink bottles, compact discs, rubber tires, and enamel paints represent only a few of the products made from this group. Polyesters most commonly are prepared from a condensation reaction between an organic alcohol containing hydroxyl [OH] groups and a carboxylic acid containing carboxyl [COOH] groups.
These two functional groups react to form the characteristic ester linkage, a chemical group with the structure:. The precise composition and structure of these repeating units vary widely, but roughly speaking they can be grouped into chains that are aliphatic i. Among the aliphatic group are the unsaturated polyestersa class of resins that are molded into fibreglass -reinforced structures such as pleasure-boat hulls.
Another aliphatic polyester is polyglycolic acid, a special type of degradable polymer that is made into bioabsorbable surgical sutures. Ring-containing polyesters are the larger and commercially more important group. By far the most prominent member of this class is polyethylene terephthalate PETa stiff, strong polymer that is spun into fibres known by such trademarks as Dacron and Terylene. PET is also extruded into the film known as Mylar and is blow-molded into disposable beverage bottles.
A related polyester is polybutylene terephthalate PBT. PBT is used in applications similar to those of PET, and it is also employed in a synthetic rubber known as copolyester elastomer.
In general, the more aromatic groups included in the repeating units, the stiffer and higher-melting the polymer. This rule can be illustrated by polycarbonatea rigid, tough, crystal-clear resin from which compact discs are made, and the polyarylatesa class of engineering plastics that often take the place of metals in machine parts. Alkyd resins are oil-modified polyesters used in paints, varnishes, and other kinds of coating materials.
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Read More on This Topic. When a carboxylic acid with two carboxyl groups is esterified with an alcohol containing two hydroxyl groups, long chains called polyesters Get exclusive access to content from our First Edition with your subscription.
Subscribe today. Learn More in these related Britannica articles:. When a carboxylic acid with two carboxyl groups is esterified with an alcohol containing two hydroxyl groups, long chains called polyesters can be made.Polyester is a category of polymers that contain the ester functional group in their main chain. As a specific materialit most commonly refers to a type called polyethylene terephthalate PET.
Polyesters include naturally occurring chemicals, such as in the cutin of plant cuticlesas well as synthetics such as polybutyrate. Natural polyesters and a few synthetic ones are biodegradablebut most synthetic polyesters are not.
The material is used extensively in clothing.
Polyester fibers are sometimes spun together with natural fibers to produce a cloth with blended properties. Cotton -polyester blends can be strong, wrinkle- and tear-resistant, and reduce shrinking. Synthetic fibers using polyester have high water, wind and environmental resistance compared to plant-derived fibers.
They are less fire-resistant and can melt when ignited. 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. Natural polyesters could have played a significant role in the origins of life. Depending on the chemical structure, polyester can be a thermoplastic or thermoset. There are also polyester resins cured by hardeners; however, the most common polyesters are thermoplastics.
What is Polyester Fabric: Properties, How its Made and Where
The OH group is reacted with an Isocyanate functional compound in a 2 component system producing coatings which may optionally be pigmented. 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 fibers have high tenacity and E-modulus as well as low water absorption and minimal shrinkage in comparison with other industrial fibers.
Unsaturated polyesters UPR are thermosetting resins. They are used in the liquid state as casting materials, in sheet molding compoundsas fiberglass laminating resins and in non-metallic auto-body fillers. They are also used as the thermoset polymer matrix in pre-pregs. Fiberglass-reinforced unsaturated polyesters find wide application in bodies of yachts and as body parts of cars.
Increasing the aromatic parts of polyesters increases their glass transition temperaturemelting temperature, thermal stabilitychemical stability They are then used as prepolymers. 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 car tire 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.
Polyester fabrics are highly stain-resistant—in fact, the only class of dyes which can be used to alter the color of polyester fabric are what are known as disperse dyes. Polyesters are also used to make bottles, films, tarpaulinsails Dacroncanoes, liquid crystal displayshologramsfiltersdielectric film for capacitorsfilm insulation for wire and insulating tapes. 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. To make a polymer of high molecular weight a catalyst is needed. The most common catalyst is antimony trioxide or antimony tri-acetate :. Inabout 10, tonnes Sb 2 O 3 were used to produce around 49 million tonnes polyethylene terephthalate. In the following table, 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 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.Polyesters are one of the most important classes of thermoplastic polymers.
They can be formed from the reaction of a diacid or acid anhydride and a diol with the elimination of water, or by ring-opening polymerization of cyclic di- esters.
According to the composition of their main chain, polyesters are classified as aliphaticsemi-aromatic and aromatic see table below.
Aromatic reactants improve the hardness, rigidity, and heat resistance, whereas aliphatic acids and diols increase the flexibility, lower the melting or softening point and improve the processability. Common aliphatic diols are ethylene glycol, 1,4-butanediol, and 1,3-propanediol.
They are often reacted with aromatic diacids, such as terephthalic acid, phthalic acid, phthalic anhydride and naphthalene dicarboxylic acid. Glycerol and unsaturated acids anhydrides like maleic anhydride, are sometimes added to crosslink the polyesters.
In the case of unsaturated acids anhydridescrosslinking is achieved in a subsequent free radical chain polymerization. Double bonds in the backbone of the polyesters also improve the resistance to softening and deformation at elevated temperatures. A large number of polyesters exist due to the numerous possible combinations of dialcohols and diacids.
However, only a small number have gained commercial significance. Both are semi-aromatic and are either amorphous when solidified by rapid cooling or semi-crystalline when solidified slowly. Both polyesters can be easily molded or thermoformed and have many attractive properties, like high strength and toughness, good abrasion and heat resistance, low creep at elevated temperatures, good chemical resistance and excellent dimensional stability, particularly when glass-fiber reinforced.
Another important polyester is polyethylene naphthalate PEN. PEN usually surpasses PET in top end demanding applications and is often a good and less expensive alternative to polyimides. Completely aliphatic polyesters, made from aliphatic diacid and aliphatic diol components, are produced on a much smaller scale.
They have low melting or glass transition temperatures and poor hydrolytic stability. They are mainly used as low-molecular-weight plasticizers and as prepolymer reactants in the synthesis of polyurethanes. A few other aliphatic polyesters are known for their biocompatibility and biodegradability, and their capability to be blended with various other commercial polymers.
Polycaprolactone PLC has good water, oil, and solvent resistance. This polymer is often blended with other resins to improve their processing and end use properties. It can also be blended with starch to lower cost and to increase the biodegradability. PLC resin blends are also used as a feedstock for injection-molding of disposable articles like drinking cups and food containers.
However, the market share of biodegradable polymers is rather small but is expected to grow. Fully aromatic polyesters have found very few commercial applications.
Due to their high crystallinity, they are difficult to process. They have high softening points - Kgood dielectric strength, excellent mechanical properties, and good heat resistance. For example, the aromatic polyester produced by the polycondensation of 4-hydroxybenzoic acid and 6-hydroxynaphthalenecarboxylic acid Vectran LCP is on a pound-for-pound basis five times stronger than steel. Other important aromatic polyesters are polyarylates PAR.
They are amorphous thermoplastics produced from terephtalic acid or phthalic acid, and bisphenols.Chemically, polyester is a polymer primarily composed of compounds within the ester functional group. Most synthetic and some plant-based polyester fibers are made from ethylene, which is a constituent of petroleum that can also be derived from other sources.
While some forms of polyester are biodegradable, most of them are not, and polyester production and use contribute to pollution around the world. Use of polyester in apparel reduces production costs, but it also decreases the comfortability of apparel. When blended with cotton, polyester improves the shrinkage, durability, and wrinkling profile of this widely-produced natural fiber.
Polyester fabric is highly resistant to environmental conditions, which makes it ideal for long-term use in outdoor applications. The fabric we now know as polyester began its climb toward its current critical role in the contemporary economy in as Terylene, which was first synthesized by W. Carothers in the UK. Throughout the s and s, British scientists continued to develop better forms of ethylene fabric, and these efforts eventually garnered the interest of American investors and innovators.
Polyester fiber was originally developed for mass consumption by the DuPont Corporation, which also developed other popular synthetic fibers like nylon. During World War II, the Allied powers found themselves in increased need of fibers for parachutes and other war materiel, and after the war, DuPont and other American corporations found a new consumer market for their synthetic materials in the context of the postwar economic boom.
Initially, consumers were enthusiastic about the improved durability profile of polyester compared to natural fibers, and these benefits are still valid today. In recent decades, however, the harmful environmental impact of this synthetic fiber has come to light in great detail, and the consumer stance on polyester has changed significantly. Apparel that contains polyester, however, will melt in extreme heat, while most natural fibers char. Molten fibers can cause irreversible bodily damage.
The production processes used to make polyester may vary depending on the type of polyester is made:. Ethylene polyester PET is the most commonly-produced form of polyester fiber.
The primary component of PET is petroleum-derived ethylene, and in the process of creating polyester fiber, ethylene serves as the polymer that interacts with other chemicals to create a stable fibrous compound.
There are four ways to make PET fiber, and the polyester production process varies slightly depending on which method is used:. Filament: Polyester filaments are continuous fibers, and these fibers produce smooth and soft fabrics.
Staple: Polyester staples resemble the staples used to make cotton yarn, and like cotton staples, polyester staples are usually spun into a yarn-like material. Tow: Polyester tow is like polyester filament, but in polyester tow, the filaments are loosely arranged together. Fiberfill: Fiberfill consists of continuous polyester filaments, but these filaments are produced specifically to have the most possible volume to make bulky products like pillows, outerwear, and stuffing for stuffed animals.
The process of creating polyester fiber begins with reacting ethylene glycol with dimethyl terephthalate at high heat. This reaction results in a monomer, which is then reacted with dimethyl terephthalate again to create a polymer. This molten polyester polymer is extruded from the reaction chamber in long strips, and these strips are allowed to cool and dry, and then they are broken apart in to small pieces.
The resulting chips are then melted again to create a honey-like substance, which is extruded through a spinneret to create fibers. Depending on whether filaments, staple, tow, or fiberfill fibers are desired, the resulting polyester filaments may be cut or reacted with various chemicals to achieve the correct end result.
In most applications, polyester fibers are spun into yarn before they are dyed or subjected to other post-production processes. The process of creating PCDT polyester is similar to the process of creating PET polyester, but this polyester variant has a different chemical structure.
While PCDT also consists of ethylene glycol reacted with dimethyl terephthalate, different production processes are used to make these two common polyester variations.
Most types of plant-based polyester are also made from ethylene glycol reacted with dimethyl terephthalate. While the source of the ethylene used in PET and PCDT polyester is petroleum, however, producers of plant-based polyester use ethylene sources like cane sugar instead.
PPC 1121: Polyester Polymer Concrete
For instance, this plastic is used to make food containers, water bottles, and a variety of other types of industrial and consumer products. In its fiber form as polyester fabric, however, PET is used in hundreds of different consumer applications.Polyesters are polymers made by a condensation reaction taking place between monomers in which the linkage between the molecules occurs through the formation of ester groups.
The esters, which in almost all cases link an organic alcohol to a carboxylic acidhave the general structure. The major industrial polyesters include polyethylene terephthalate, polycarbonate, degradable polyesters, alkyds, and unsaturated polyesters.
PET is produced by the step-growth polymerization of ethylene glycol and terephthalic acid. The presence of the large benzene rings in the repeating units. The stiffness of PET fibres makes them highly resistant to deformation, so that they impart excellent resistance to wrinkling in fabrics.
They are often used in durable-press blends with other fibres such as rayon, wool, and cotton, reinforcing the inherent properties of those fibres while contributing to the ability of the fabric to recover from wrinkling. PET is also made into fibre filling for insulated clothing and for furniture and pillows. When made in very fine filaments, it is used in artificial silkand in large-diameter filaments it is used in carpets.
Among the industrial applications of PET are automobile tire yarns, conveyor belts and drive belts, reinforcement for fire and garden hoses, seat belts an application in which it has largely replaced nylonnonwoven fabrics for stabilizing drainage ditches, culverts, and railroad beds, and nonwovens for use as diaper top sheets and disposable medical garments.
PET is the most important of the man-made fibres in weight produced and in value. At a slightly higher molecular weightPET is made into a high-strength plastic that can be shaped by all the common methods employed with other thermoplastics.
Recording tape and magnetic film is produced by extrusion of PET film often sold under the trademarks Mylar and Melinex. Molten PET can be blow-molded into a transparent container of high strength and rigidity that also possesses good impermeability to gas and liquid. In this form PET has become widely used in carbonated-beverage bottles and in jars for food processed at low temperatures. It is the most widely recycled plastic. PET was first prepared in England by J.
Rex Whinfield and James T. Dickson of the Calico Printers Association during a study of phthalic acid begun in Because of wartime restrictions, patent specifications for the new material, named Terylene, were not published, and production by ICI did not begin until Meanwhile, by DuPont had independently developed a practical preparation process from terephthalic acid, and in the company began to produce Dacron.
PBT, a strong and highly crystalline engineering plastic, is similar in structure to PET but has a lower melting pointso it can be processed at lower temperatures.
Either unmodified or reinforced with glass fibres or mineral fillers, it is used in numerous applications, especially electrical and small machine parts, owing to its excellent electrical resistancesurface finish, and toughness.
Pipe made with PBT so-called polybutylene pipe, or PB pipe was formerly popular for residential plumbing as a low-cost and easily handled substitute for copper, but it was found to degrade after prolonged contact with oxidizing chemicals such as chlorine in municipal water supplies, and so it is no longer used. Marketed under the trademarked names Lexan and Merlon, among others, PC is a special type of polyester used as an engineering plastic. It has exceptional stiffness, mainly by virtue of having more aromatic rings incorporated into the polyester chain:.
This structure is arrived at by reacting bisphenol Aan aromatic derivative of benzene, with phosgene, a highly reactive and toxic gas. Polycarbonate is highly transparent, has an impact strength considerably higher than most plastics, and can be injection-molded, blow-molded, and extruded.
These properties lead to its fabrication into large carboys for water, shatter-proof windows, safety shields, and safety helmets. It is the favoured plastic for injection-molding into compact discs. Several degradable polyesters are commercially available. PHB, on the other hand, is made from sugars and starches by bacterial action. Degradation of the ester groups linking the monomers is brought about by microorganisms or water.
Because the degradation products are natural metabolites, the polymers are of interest in medical applications. Besides being made into degradable bottles and packaging film, these compounds can find applications in controlled-release drug packaging and in absorbable surgical sutures. Alkyds, or alkyd resins, are highly complex network polyesters that are manufactured for the paint industry.
Developed from research conducted at the General Electric Co. To the ester-forming monomers are added modifiers consisting of unsaturated oils such as tung oillinseed oil, or dehydrated castor oil.All forms provide good chemical resistance and durability.
Data is to be considered representative and is provided for guidance only. All product performance must be verified by the user under actual application conditions.
Our materials experts will help identify the right solution for your application, put together a quote and a detailed timeline. Polyethylene Terephthalate — known as PET or Polyester— is a thermoplastic polymer that can be amorphous, crystalline, or a mixture of both, depending on how it is processed. Polymershapes offers a wide selection of polyester in sheet, film, rod and tube.
Polyester is known for having high dimensional stability coupled with excellent wear resistance, a low coefficient of friction, high strength, and resistance to moderately acidic solutions.
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Its low moisture absorption enables mechanical and electrical properties to remain virtually unaffected by moisture. These properties make it especially suitable for the manufacture of precision mechanical parts which must sustain high loads and endure persistent wear.
And did you know Polymershapes has the capabilities to be your one-stop shop for all your plastics needs? Ask about our precision cutting and fabrication capabilities to deliver on your specific polyester requirements. We can provide you with any of our high-quality plastics and materials in the length, width and thickness you need. With Engineering Plastics from Polymershapes, you can go where your inspiration takes you!
For all your Polyester needs — and much, much more! Be the first to see our latest promotions, new materials and valuable informative content by signing up for our newsletter. Polyester PET. High strength and rigidity — ideal for close tolerance parts. Good wear resistance and excellent dimensional stability. Better resistance to acids than nylon or acetal. Product Options. General Purpose. Technical Resources. Polymer Industries. Common Applications. Physical Properties.
Have questions? Need a quote? Request Information. View All 5 Regulations. Have a project? Get in touch! About Polyester PET. Stay Connected Be the first to see our latest promotions, new materials and valuable informative content by signing up for our newsletter.Polyester was developed in the years by British chemists at Calico Printers Association, Ltd.
Carothers i n at the United States based E. Pont de Nemours and Co. DuPont bought the rights in to produce polyester fiber in the United States. ByDuPont had begun to market the fiber under the name Dacron. Polyester is made up of long-chain polymers. However, PCDT is more elastic and resilient and is used in heavier consumer applications. Synthetic polyester is made using a chemical reaction involving coal, petroleum, air and water.
The most common type of chemical reaction used to make polyester takes place at high temperatures in a vacuum. The polymer material created during polymerization is extruded while hot into long fibers that are stretched until they are about five times their original length. The resultant fiber forms an arrangement of molecules that is very strong.
Fibers or threads of this material are made using a spinning process.Terylene/ Dacron ( polyester polymer )
There are two types of spinning processes. Synthetic fabrics like polyester are often criticized for having a less natural feel than fabrics such as cotton, silk, or wool. However, it does have some distinct advantages over natural fibers. Synthetic fibers also can exhibit superior water, wind and environmental resistance. Polyester fabrics have come to replace some of the old school natural fabrics.
This material can be a thermoplastic or thermoset. Most polyesters are thermoplastics, meaning they may change their shape with the application of heat. It is combustible at high temperatures but tends to shrink away from flames and is self-extinguishing upon ignition. So just leave your windbreakers off of the ironing board!
Unsaturated polyesters UPR are thermoset resins. They are used for non-metallic body fillers, fiberglass laminating resins, and casting materials. Fiberglass-reinforced unsaturated polyesters are used in a wide range of applications including the bodies of yachts and automobiles.