Polytrimethylene terephthalate (PTT), is a

polyester Polyester is a category of polymers that contain one or two ester linkages in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include some natura ...

synthesized and patented in 1941. It is produced by a method called

condensation polymerization In polymer chemistry, condensation polymers are any kind of polymers whose process of polymerization involves a condensation reaction (i.e. a small molecule, such as water or methanol, is produced as a byproduct). Natural proteins as well as s ...

transesterification Transesterification is the process of exchanging the organic functional group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. Strong acids catalyze the r ...

. The two

monomer A monomer ( ; ''mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or two- or three-dimensional network in a process called polymerization. Classification Chemis ...

units used in producing this polymer are: 1,3-propanediol and

terephthalic acid Terephthalic acid is an organic compound with formula C6H4(CO2H)2. This white solid is a commodity chemical, used principally as a precursor to the polyester PET, used to make clothing and plastic bottles. Several million tons are produced annuall ...

dimethyl terephthalate Dimethyl terephthalate (DMT) is an organic compound with the formula . It is the ester, diester formed from terephthalic acid and methanol. It is a white solid that melts to give a distillable colourless liquid. Production Dimethyl terephthalat ...

. Similar to

polyethylene terephthalate Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in synthetic fibre, fibres for clothing, packaging, conta ...

, the PTT is used to make

carpet A carpet is a textile floor covering typically consisting of an upper layer of Pile (textile), pile attached to a backing. The pile was traditionally made from wool, but since the 20th century synthetic fiber, synthetic fibres such as polyprop ...

fibers. PTT's value as a commercial polymer has improved due to more economical and efficient methods to produce 1,3-propanediol in the 1980s by Degussa, via

acrolein Acrolein (systematic name: propenal) is the simplest unsaturated aldehyde. It is a colorless liquid with a foul and acrid aroma. The smell of burnt fat (as when cooking oil is heated to its smoke point) is caused by glycerol in the burning fat ...

, and

Shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

via the hydroformylation of

ethylene oxide Ethylene oxide is an organic compound with the chemical formula, formula . It is a cyclic ether and the simplest epoxide: a three-membered ring (chemistry), ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless ...

DuPont Dupont, DuPont, Du Pont, duPont, or du Pont may refer to: People * Dupont (surname) Dupont, also spelled as DuPont, duPont, Du Pont, or du Pont is a French surname meaning "of the bridge", historically indicating that the holder of the surname re ...

has successfully commercialized the production of this polymer via 1,3-propanediol obtained by fermentation. These developments may allow PTT to effectively compete against PBT and

PET A pet, or companion animal, is an animal kept primarily for a person's company or entertainment rather than as a working animal, livestock, or a laboratory animal. Popular pets are often considered to have attractive/ cute appearances, inte ...

, two polyesters that have been far more successful than PTT to date.

Production

Similar to the ubiquitous

poly(ethylene terephthalate) Polyethylene terephthalate (or poly(ethylene terephthalate), PET, PETE, or the obsolete PETP or PET-P), is the most common thermoplastic polymer resin of the polyester family and is used in synthetic fibre, fibres for clothing, packaging, conta ...

, this polymer is prepared by the esterification of 1,3-propanediol (HO(CH₂)₃OH) with

(C₆H₄(COOH)₂), or by transesterification of

: This polymer has been commercialized as

Sorona Sorona is DuPont de Nemours, Inc.'s brand of Triexta, a subclass of polytrimethylene terephthalate (PTT) named and commercialized in 2000. The fibers are soft and stain-resistant while exhibiting high strength and stiffness. Sorona is a co-poly ...

Applications

On Friday, March 20, 2009, the Federal Trade Commission approved a subclass to polyester called triexta. The PTT fiber used in Mohawk's SmartStrand carpet, and branded Sorona by Dupont can be labeled triexta. Triexta has been reported to have several advantages over polyethylene terephthalate, including better stain resistance and softness.{{Cite web , title=Triexta PTT Carpet Fiber , last=Simmons , first=Cheryl , work=The Spruce , date=8 August 2019 , url= https://www.thespruce.com/triexta-ptt-carpet-fiber-2908799 The FTC had last approved an extension for residential carpet in 1959. Mohawk Industries and DuPont applied jointly for FTC approval of the triexta polyester subclass in 2006; it was approved three years later.

References

External links

Forensic Science Communications literature review of Polytrimethylene terephthalate
Polyesters Plastics Terephthalate esters