Polyester Totally Explained

Everything about Polyester totally explained

Polyester (aka Terylene) is a category of polymers which contain the ester functional group in their main chain. Although there are many forms of polyesters, the term "polyester" is most commonly used to refer to polyethylene terephthalate (PET). Other forms of polyester include the naturally-occurring cutin of plant cuticles as well as synthetic polyesters such as polycarbonate and polybutyrate.
Polyester may be produced in numerous forms. For example, polyester as a thermoplastic may be heated and processed into different forms and shapes, for example, fibers, sheets and three-dimensional shapes. While combustible at high temperatures, polyester tends to shrink away from flames and self-extinguishes. Industrial polyester fiber have high tenacity and E-modulus, low water absorption and shrinkage properties compared to other industrial fibers as polyamid fibers.

Applications

Polyester is the most widely used man-made fiber in the world. The industrial applications become more and more important. Woven polyester fabrics are used for apparel, home furnishings and a wide range of industrial uses. These include bed sheets, bedspreads, curtains and draperies. Industrial applications are: tyre reinforcements, ropes, fabrics for conveyor belts, safety belts, coated fabrics, plastic reinforcements with high energy absorption, e.g Diolen(R) in wild water canoes. Polyester fiberfill is also used to stuff pillows, comforters and cushion padding.
   Polyester fabrics sometimes have a "less natural" feel when compared to similarly-woven fabrics made from natural fibers, for example, cotton in textile uses. This are significant advantages in industrial uses. However, polyester fabrics may exhibit other advantages over natural fabrics, for example improved wrinkle resistance. As a result, polyester fibers are often spun together with natural fibers, for example cotton, to produce a cloth with blended properties. Polyesters are also used to make bottles, films,tarpaulin, reinforcement of plastics for SF6 switches, canoes, liquid crystal displays, holograms, filters, dielectric film for capacitors, film insulation for wire and insulating tapes.
   Liquid crystalline polyesters are among the first, industrially-used liquid crystalline polymers. In general they've extremely good mechanical properties and are extremely heat resistant. For that reason, they can be used as an abradable seal in jet engines. Thermosetting polyester resins are generally copolymers of unsaturated polyesters with styrene. The unsaturation in the polyester is generally governed by maleic acid or fumaric acid. Another important family is the group of vinyl esters. Here the unsaturation is found in the alcohol part of the polyester. The double bond of the unsaturated polyester reacts with styrene resulting in a 3-D crosslinked structure, the thermoset material. The cross-linking is initiated through an exothermic reaction involving an organic peroxide, such as methyl ethyl ketone peroxide or benzoyl peroxide. Unsaturated polyesters are commonly used as casting materials, fiberglass laminating resins, and non-metallic auto-body fillers. Fiberglass-reinforced, unsaturated polyesters find wide application in bodies of yachts and as body parts of cars.
   Polyester is also widely used as a finish on high-quality wooden products like guitars, pianos and vehicle/yacht interiors (Burns Guitars, Rolls Royce and Sunseeker are examples of companies that use polyester on their products). The thixotropic properties of the sprayable form of polyester make it ideal for use on open-grain timbers, as it can quickly fill the grain and has a high-build film thickness per coat. The cured polyester can then be sanded and polished to a high-gloss, durable finish.

Polyester fiber properties

1. Mechanical properties (will continued soon) Energy absorption of chemical fiber reinforced plastics (impact, bending and tensile tests) Investigation of the practical requirements for measuring the energy absorption of composite materials, and development of a suitable method for carrying out such measurements. A number of dynamic testing methods for measuring the energy absorption of laminates are reviewed, including animpact bending test, repeated-impact tests, an impact tensile test, and a ram bending test. Also discussed are impact tests on plate laminates. Particular emphasis is placed in these studies on composites with a chemical fiber reinforcement. It is established that a relation exists between the quasi-static energy absorption of the fibers and the dynamic energy absorption of the composite. Composites with commercial polyester and polyamide fibers lead to the highest energy absorptions, in which case the testing apparatus has a significant effect.
2. Chemical properties (will be edit soon)

The polyester industry

Some basics

To get an idea about coverage, importance and complexity of the polyester industry, some basic information about polyester or polyethylene terephthalate (PET) at first:
   What is polyester? Polyester is a synthetic polymer made of purified terephthalic acid (PTA) or its dimethyl ester dimethyl terephthalate (DMT) and monoethylene glycol (MEG). It ranges after polyethylene and polypropylene at the third place in terms of market size.
   The main raw materials are described as follows:
Purified Terephthalic Acid – PTA – CAS-No.: 100-21-0 Synonym: 1,4 Dibenzenedicarboxylic acid, Sum formula; C6H4(COOH)2, mol weight: 166,13 Dimethylterephthalate – DMT- CAS-No: 120-61-6 Synonym: 1,4 Dibenzenedicarboxylic 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
   More information about polyester raw materials one can find for PTA,DMT and MEG, at the webpage INCHEM "Chemical Safety Information from Intergovernmental Organizations".
   To make finally a polymer of high molecular weight one needs a catalyst. The most common catalyst is antimony trioxide (or antimony tri acetate) Antimony trioxide – ATO – CAS-No.: 1309-64-4 Synonym: non, mol weight: 291,51 Sum formula: Sb2O3
   In 2008 about 10 000 t Sb2O3 are used to produce around 49 Mio t 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, mol unit weight: 192,17
   What are the success factors of the unbroken capacity growth of polyethylene terephthalate?
    ->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 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 recycle ability ->The wide variety of intermediate and final products made of polyester
   All these facts are making this polymer one of the key elements of our daily life.
   In table 1 we see the estimated world polyester production for textile polyester, bottle polyester resin, film polyester mainly for packaging and specialty polyesters for engineering plastics, which are the main fields of application. 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 - year 2002 [Miot/a] 2008 [Miot/a] Product Type Textile-PET 20 39 Resin, Bottle/ A-PET 9 16 Film-PET 1,2 1,5 Special Polyester 1,0 2,5 TOTAL 31,2 49,0
   With its production volume and product diversity, polyester ranges after polyethylene (33.5%), polypropylene (19,5%) with a market share of about 18% in third position among all plastic materials produced worldwide.
   The polyester production chain, and the relative polyester industry chain, will now be explained in greater detail and step by step.

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.
   Large PTA producers are for instance BP, Reliance, Sinopec, SK-Chemicals, Mitsui and Eastman Chemicals. MEG production is in the hand of about 10 global players which are headed by MEGlobal a JV of DOW and PIC Kuweit followed by Sabic.
   Let us assume the average production capacity of a single polyester plant is about 200 t/day: we're talking about nearly 500 polyester plants around the globe. Adding to this figure the continuously-growing polyester recycling industry, which is estimated to have processed about 3 million t polyester waste in 2007 alone (5 million T/a in 2010 estimated) and where each plant produces on average about 10 000 t/a, we've another 500 plants. This is 1000 polyester production plants, all needing specific and polyester-dedicated engineering and equipment, machinery, process technology and know-how, producing, processing and recycling polyester.
   Among the world's largest polyester producers are the following companies:
Artenius, Advansa, DAK, DuPont, Eastman/Voridian, Hyosung, Huvis, Indorama, Invista, Jiangsu Sanfangxian, M&G Group, Mitsui, Mitsubishi, NanYa Plastics,Reichhold, Reliance, Rongsheng, Sabic, Teijin, Toray, Tonkun, Tuntex, Wellman, Yizheng Sinopec and Sanfanxiang. One should notice that China's capacity to produce and process polyester in more than 500 plants is nearly half that of the world's polyester capacity meanwhile. More information about polyester in China can be found under the web site of China Chemical Fiber Economic Information Network .

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 PELLETS) 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 Softdrink; A-PET = Amorphous Polyester Film; BO-PET = Biaxial Oriented Polyester Film;
   A comparable small market segment (<< 1 million t/a) 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 t/d per spinning line) or POY /FDY (up to 600 t/d split into about 10 spinning machines) are meanwhile more and more horizontal, 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 horizontal 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 introduced at first the idea to close the chain from PX to PET resin with their so-called INTEGREX® process. The capacity of such horizontal, integrated productions sites is >1000 t/d and can easily reach 2500 t/d.
   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's still growing by 4–8% per annum, depending on the world region. Useful information about the polyester industry can be found under 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

See main article on transesterification. CH₃ + OH[Oligomer2] / [Oligomer1] 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.

Further Information

Get more info on 'Polyester'.

leftrightarrow

O \ C - O[Oligomer2] + CH₃OH / [Oligomer1]

External Link Exchanges

Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:

<a href="http://polyester.totallyexplained.com">Polyester Totally Explained</a>

Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned.