Polytrimethylene terephthalate

Polytrimethylene terephthalate (PTT), is a polyester synthesized and patented in 1941.[1][2] It is produced by a method called condensation polymerization or transesterification. The two monomer units used in producing this polymer are: 1,3-propanediol and terephthalic acid or dimethyl terephthalate. Similar to polyethylene terephthalate, the PTT is used to make carpet fibers.

Polytrimethylene terephthalate
Strukturfromel PPT.svg
Other names
Poly(trimethylene terephthalate); Poly(oxy-1,3-propanediyloxycarbonyl-1,4-phenylenecarbonyl)
  • none
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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, and Shell via the hydroformylation of ethylene oxide.[3] DuPont 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, two polyesters that have been far more successful than PTT to date.


Similar to the ubiquitous poly(ethylene terephthalate), this polymer is prepared by the esterification of 1,3-propanediol (HO(CH2)3OH) with terephthalic acid (C6H4(COOH)2), or by transesterification of dimethyl terephthalate:[3]

Reaction scheme of PTT-synthesis …
… by esterification.
… by transesterification.

This polymer has been commercialized as Sorona by DuPont.


On Friday, March 20, 2009, the Federal Trade Commission approved a subclass to polyester called triexta.[4] 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.[5]

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.


  1. ^ John Rex Whinfield and James Tennant Dickson (1941) "Improvements Relating to the Manufacture of Highly Polymeric Substances", UK Patent 578,079; "Polymeric Linear Terephthalic Esters", U.S. Patent 2,465,319 Publication date: March 22, 1949; Filing date: September 24, 1945; Priority date: July 29, 1941
  2. ^ Max M. Houck; et al. (July 2001). "Poly(Trimethylene Terephthalate): A "New" Type of Polyester Fiber". Forensic Science Communications. 3 (3). Archived from the original on November 11, 2005.
  3. ^ a b Helmut Sattler; Michael Schweizer. "Fibers, 5. Polyester Fibers". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.o10_o01.
  4. ^ "FTC Approves Federal Register Notice Establishing New Fiber Name and Definition" (Press release). Federal Trade Commission. 2009-03-20.
  5. ^ Simmons, Cheryl (8 August 2019). "Triexta PTT Carpet Fiber". The Spruce.

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