Name: polyester uses and pet production
Uploaded: 2023-04-30T11:25:17.000Z
Duration: 1 min 20 s
Channel: JoVE

Polymers in which the monomers are joined together by an ester bond are called polyesters.
Typically, dicarboxylic acids and diols undergo stepwise condensation to yield polyesters.
For instance, terephthalic acid and ethylene glycol undergo Fischer esterification and lose water to form poly(ethylene terephthalate), or PET.
PET can also be prepared from dimethyl terephthalate and ethylene glycol via a transesterification process with the loss of methanol.
Crude PET can be blow-molded to make soft-drink bottles, spun into Dacron fiber, or cast into Mylar film.
Dacron fiber is widely used in the textile industry because of its light weight, high strength, and moisture resistance properties.
Mylar film is used to manufacture magnetic recording tapes, as it is strong, flexible, and resistant to ultraviolet degradation.
Kodel is another polyester prepared by transesterification of dimethyl terephthalate and 1,4-di(hydroxymethyl)cyclohexane.
It is generally used by blending it with wool or cotton to reduce stiffness.

types of step-growth polymers: polyesters

Types of Step-Growth Polymers: Polyesters

The introduction of polyesters has brought major development to the textile industry. The wrinkle-free behavior of polyester blends has eliminated the need for starching and ironing clothes.
Polyesters are commonly prepared from terephthalic acid and ethylene glycol; the crude product is known as poly(ethylene terephthalate) or PET. However, polyesters are synthesized industrially by transesterification of dimethyl terephthalate with ethylene glycol at 150 &#176;C. The two reactants and the polymer PET are not volatile at this temperature, but the by-product methanol vaporizes from the reaction, thereby driving the reaction to completion.
For PET synthesis, ethylene glycol is obtained by the air-oxidation of ethylene to ethylene oxide, which upon hydrolysis, gives glycol. Terephthalic acid is prepared by the oxidation of p-xylene.
<img alt="Chemical process diagram: Ethylene oxidation, p-xylene oxidation to terephthalic acid, catalyst use." src="/files/ftp_upload/12932/12932_PT_Figure_1.svg" style="text-align: center; height: 225px;" data-altupdatedat="1761830439000" data-alt="Figure1" />
The crude PET can be spun into a Dacron fiber, most commonly used in the textile industry as a clothing material. It can also be fabricated into a film called Mylar. These films are used to prepare magnetic recording tape. Thicker Mylar films are used in compact discs. Poly(ethylene terephthalate) is also blow-molded to make plastic bottles used for soft drinks.
Some polyesters are unstable because they get hydrolyzed in the aqueous medium. Such polyesters find applications where slow degradation is required. For example, the copolymer of glycolic acid and lactic acid is used by surgeons in dissolvable sutures. The copolymer gets hydrolyzed within weeks into starting materials, which get metabolized inside the body.
<img alt="Copolymerization process; glycolic, lactic acids to copolymer; enzymatic hydrolysis; chemical equation." src="/files/ftp_upload/12932/12932_PT_Figure_2.svg" style="text-align: center; height: 175px;" data-altupdatedat="1761830439000" data-alt="Figure2" />

The introduction of polyesters has brought major development to the textile industry. The wrinkle-free behavior of polyester blends has eliminated the ...

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Organic Chemistry

Unit 1

Synthetic Polymers

KEY TERMS AND CONCEPTS

polyester uses and pet production

Polyesters are widely used step-growth polymers, and PET is one of the most important examples. These materials helped transform the textile industry because polyester blends resist wrinkles. That reduced the need for starching and ironing clothes.

Industrial PET is made from dimethyl terephthalate and ethylene glycol by transesterification at 150 °C. In this process, methanol is the by-product. It vaporizes at the reaction temperature, which helps drive the reaction to completion. PET can also be prepared from terephthalic acid and ethylene glycol, and the crude polymer is called poly(ethylene terephthalate), or PET.

The starting materials for PET come from other chemical steps. Ethylene glycol is made by air-oxidizing ethylene to ethylene oxide, then hydrolyzing it to glycol. Terephthalic acid is prepared by oxidizing p-xylene. These production steps supply the raw materials needed for polyester synthesis.

PET has several common forms and uses. It can be spun into Dacron fiber for clothing. It can also be made into Mylar film, which is used for magnetic recording tape. Thicker Mylar films are used in compact discs, and PET is also blow-molded into plastic bottles for soft drinks.

Some polyesters are unstable in water because they hydrolyze in aqueous media. These materials are useful when slow degradation is needed. One example is the copolymer of glycolic acid and lactic acid, which surgeons use in dissolvable sutures. It hydrolyzes within weeks into starting materials that the body can metabolize.

Polyester Uses and PET Production

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Copolymers are polymers made from more than one kind of monomer. When different monomer species are polymerized together, the chain can contain multiple repeating units. This process is called copolymerization. Copolymers can be named by the number of monomers involved. A polymer made from two monomers is a bipolymer. Polymers made from three monomers are called terpolymers, and those made from four monomers are quaterpolymers. A common example is poly(styrene-co-acrylonitrile), also called...

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Polyesters are widely used step-growth polymers, and PET is one of the most important examples. These materials helped transform the textile industry because polyester blends resist wrinkles. That reduced the need for starching and ironing clothes. Industrial PET is made from dimethyl terephthalate and ethylene glycol by transesterification at 150 °C. In this process, methanol is the by-product. It vaporizes at the reaction temperature, which helps drive the reaction to completion. PET can...

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key terms and concepts

Explore how PET is made from terephthalic acid or dimethyl terephthalate and ethylene glycol, plus its uses in fibers, films, bottles, and dissolvable sutures.

Polyester Uses and PET Production | JoVE K12

organic chemistry

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Polyester Uses and PET Production

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