Poly trimethylene Terephthalate

Although poly(trimethylene terephthalate) has been known for many years it was only introduced by Shell in the late 1990s as a consequence of a breakthrough in the synthesis of the monomer 1,3-propane diol which enabled the polymer to be produced at costs suitable for commercialisation. The polymer itself is prepared by melt condensation of the diol with terephthalic acid. 

In most respects PTT can be considered as intermediate in properties between PBT and PET but does appear to possess two special properties  

As is common for crystalline thermoplastics the deflection temperature of unfilled grades is similar to Tg (quoted as being in the range 45-70°C) while for glass-filled grades it is much closer to the of 225°C. 

More to be expected of a more hydrocarbon polymer than PET is a somewhat lower water absorption, typically about 70% that of PET. With appropriate flame retardants, grades can have a UL V-0 rating at 0.8 mm thickness. 

PCT may be used for the production of electronic and automotive components such as circuit board components, connectors, switches and relays, and alternator armatures and pressure sensors. The main application has been in the fabrication of surface-mount coimectors that can withstand infrared reflow soldering operations. 

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TABLE 2.11 Typical Properties of Unfilled Polyethylene terephthalate) (PET), Poly(trimethylene terephthalate) (PTT), and Poly(butylene terephthalate (PBT) Solid-State Polyester Resins... 

H. H. Chuah, Corterra Poly (trimethylene) terephthalate — New Polymeric Fiber for Carpets, Paper presented at Tifcon 96, Blackpool, U.K. (1966). http //www. shellchemicals.com. 

Journal of Applied Polymer Science 82, No. 1, 3rd October 2001, p.99-107 ALKALINE DEPOLYMERISATION OF POLY(TRIMETHYLENE TEREPHTHALATE)... 

Poly(trimethylene terephthalate) (PTT) is a polymer with very useful properties. As a textile fibre it has excellent softness, stretch and recovery. As a resin it has excellent barrier properties. Developed over 60 years ago, PTT has not been very widely used compared to poly(ethylene terephthalate) (PET) as one of the key monomers 1,3-propanediol (PDO) has been expensive. 

Synthesis, Properties and Applications of Poly(Trimethylene Terephthalate)... 

Poly(trimethylene terephthalate) (PTT) is a newly commercialized aromatic polyester. Although available in commercial quantities only as recently as 1998 [1], it was one of the three high-melting-point aromatic polyesters first synthesized by Whinfield and Dickson [2] nearly 60 years ago. Two of these polyesters, polyethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT), have become well-established high-volume polymers. PTT has remained an obscure polymer until recent times because one of its monomers, 1,3-propanediol (PDO), was not readily available. PDO was sold as a small-volume fine chemical at more than 10/lb., and was therefore not suitable as a raw material for commercial polymers. 

Figure 11.1 The chemical structure of poly(trimethylene terephthalate)...

Figure 11.7 Experimental and calculated heat capacities of solid and liquid PTT [49], From Heat capacity of poly(trimethylene terephthalate), Pyda, M., Boiler, J., Grebowicz, J., Chuah, H., Lebedev, B. V. and Wunderlich, B., J. Polym. Sci., Polym. Phys. Ed., 36, 2499-2511 (1998), Copyright (1998 John Wiley Sons, Inc.). Reprinted by permission of John Wiley Sons, Inc...

Figure 11.14 Effect of applied strain on the 002 d-spacing of a PTT fiber drawn at 3.3 x measured by WAXD [76], Reprinted from Polymer, 42, Wu, J., Schultz, J. M., Samon, K. M., Pangelinan, A. B. and Chuah, H. H., In situ study of structure development in poly(trimethylene terephthalate) fibers during stretching by simultaneous synchrotron small- and wide-angle X-ray scattering, 7141-7151, Copyright (2001), with permission from Elsevier Science...

Figure 11.16 PTT WAXD pattern and indices of the reflections [45]. From Polym. Bull., Crystal orientation function of poly(trimethylene terephthalate) by wide-angle X-ray diffraction, Chuah, H. H. and Chang, B. T. A., 46, p. 310, Figure 2, Copyright Springer-Verlag (2001). Reproduced by permission of Springer-Verlag GmbH Co. KG...

Chuah, H. H., Wemy, F. and Langley, T., Dyeing and staining of poly(trimethylene terephthalate) carpets, in Proceedings of the Book of Paper International Conference and Exhibition, October 8-11, 1995, Atlanta, GA, The American Association of Textile Chemists and Colorists, Research Triangle Park, NC, 1995, pp. 98-106. 

Kiibler, K. S., C. A. Caico, Lin-Vien, D. and French, R. N Byproduct Emissions from Poly(trimethylene terephthalate) Studies on the Release of Acrolein and Allyl Alcohol During Processing, Storage, and Shipping of PTT, Technical Information Report, WTC-3659, Shell Chemical Company, Houston, TX, 2000. 

It should be taken into account that all of the aspects described above are of a general nature and therefore more or less valid for any kind of industrially relevant polyester resin. Upon closer examination, the experiences gained with PET are particularly applicable to poly(butylene terephthalate) (PBT), poly(trimethylene terephthalate) (PTT) and polyethylene naphthalate) (PEN). These polymers have gained major industrial importance as a result of a number of different properties in comparison with PET. 

The newest commercial polymer to join the polyester family is poly(trimethylene terephthalate) (PTT) which is being targeted at fibre applications (Chapter 11). It is sold under the Corterra trademark by Shell. After packaging, the single largest use for polyesters is for fibre applications such as clothing, textiles and non-wovens. The technology of polyester fibre formation is described in Chapters 12 and 13. 

Propanediol. Both the diol and the dicarboxylic acid components of poly-trimethylene-terephthalate, a high performance polyester fiber with extensive applications in textile apparel and carpeting, are currently manufactured from petrochemical raw materials. 

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