Terephthalic acid polymer

Lurgi 01 Gas Chemie GmbH Terephthalic acid-polymer grade (MTA) p-Xylene Liquid-phase oxidation with unique mild colditions. Advanced purification, section. Effective with respect to operation and investment costs NA NA... 

Nagata, M., Goto, H., Sakai, W. and Tsutsumi, N. (2000) Synthesis and enzymatic degradation of poly(tetramethylene succinate) copolymers with terephthalic acid. Polymer, 41 (11), 4373-4376. 

A. B. Padias and FI. K. Hall, Oligomeric bishydroxybutyl terephthalates from terephthalic acid, /. Polym. Sci. Part A Polym. Chem., 19-.1021-1032,1981. 

Carboxylic acids are used in the production of polymers, pharmaceuticals, solvents, and food additives. Industrially important carboxylic acids include acetic acid (component of vinegar, precursor to solvents and coatings), acrylic and methacrylic acids (precursors to polymers, adhesives), adipic acid (polymers), citric acid (beverages), ethylenediaminetetraacetic acid (chelating agent), fatty acids (coatings), maleic acid (polymers), propionic acid (food preservative), terephthalic acid (polymers). 

Ishaq, M., Blackwell, J. Chvalun, S. N. (1996). Molecular Modeling of the Structure of the Copolyester Prepared from p-hydroxybenzoic Acid, Bisphenol and Terephthalic Acid. Polym, 37(10), 1765-1774. 

Condensation polymerization differs from addition polymerization in that the polymer is formed by reaction of monomers, each step in the process resulting in the elimination of some easily removed molecule (often water). E.g. the polyester polyethylene terephthalate (Terylene) is formed by the condensation polymerization (polycondensation) of ethylene glycol with terephthalic acid ... 

PCTA Copolyester. Poly(l,4-cyclohexanedimethylene terephthalic acid) (PCTA) copolyester is a polymer of cyclohexanedimethanol and terephthalic acid, with another acid substituted for a portion of the terephthalic acid otherwise required. It has the following formula ... 

Those polymers which are the condensation product of two different monomers are named by applying the preceding rules to the repeat unit. For example, the polyester formed by the condensation of ethylene glycol and terephthalic acid is called poly(oxyethylene oxyterphthaloyl) according to the lUPAC system, as well as poly (ethylene terephthalate) or polyethylene terephthalate. 

Fig. 4. The Amoco purification process for polymer-grade terephthalic acid.

Table 20. Specifications for Polymer-Grade Terephthalic Acid...

Polyester—any long-chain synthetic polymer composed of at least 85% hy weight of an ester of a dihydric alcohol and terephthalic acid (p—HOOC—C6H4—COOH). 2.2-7.8 E-G G G-F G G 1.38 300... 

Another recent development is the preparation of a polyester-polycarbonate copolymer. The polymers involve a polyester component based on the reaction between bis-phenol A and iso- or terephthalic acid with the carbonate component arising from the reactions described in Section 20.3 (see Section 20.9). 

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 1972 Eastman Kodak introduced a copolymer produced by reacting 1,4-cyclohexylene glycol with a mixture of isophthalic and terephthalic acids. Thus the polymer contains 1,4-cyclohexanedimethyloxy units (I), terephthalic acid units (II) and isophthalic acid units (III) Figure 25.20). 

One such material is the copolymer first marketed by the Japanese company Unitika in 1974 as U-Polymer and more recently by the Belgian company Solvay as Arylef and Union Carbide as Ardel. (Around 1986 the Union Carbide interest in Ardel, as well as in polysulphones, was taken over by Amoco.) Similar polyarylates have since been marketed by Hooker (Durel), Bayer (APE) and DuPont (Arylon). This is a copolyester of terephthalic acid, isophthalic acid and bis-phenol A in the ratio 1 1 2 Figure 25.23). 

Polymers based on these structures became available as Victrex SRP (ICI), Vectra (Hoechst) and Xydar (Amoco). It is reported that the Vectra materials are based on p-hydroxybenzoic acid and hydroxynaphthoic acid monomers, whilst Xydar is based on terephthalic acid, p-hydroxybenzoic acid and pp -dihydrox-ybiphenyl. Whilst properties vary between grades, in general they possess the following outstanding properties ... 

Polyesters are the most important class of synthetic fibers. In general, polyesters are produced by an esterification reaction of a diol and a diacid. Carothers (1930) was the first to try to synthesize a polyester fiber by reacting an aliphatic diacid with a diol. The polymers were not suitable because of their low melting points. However, he was successful in preparing the first synthetic fiber (nylon 66). In 1946, Whinfield and Dickson prepared the first polyester polymer by using terephthalic acid (an aromatic diacid) and ethylene glycol. 

Using excess ethylene glycol is the usual practice because it drives the equilihrium to near completion and terminates the acid end groups. This results in a polymer with terminal -OH. When the free acid is used (esterification), the reaction is self catalyzed. However, an acid catalyst is used to compensate for the decrease in terephthalic acid as the esterification nears completion. In addition to the catalyst and terminator, other additives are used such as color improvers and dulling agents. For example, PET is delustred hy the addition of titanium dioxide. 

At constant PBT/PTMO composition, when the molar mass of PTMO block is >2000, partial crystallization of the polyether phase leads to copolymer stiffening. The properties of polyesterether TPEs are not dramatically different when PTMO is replaced by polyethers such as poly(oxyethylene) (PEO) or poly(oxypropylene). PEO-based TPEs present higher hydrophilicity, which may be of interest for some applications such as waterproof breathable membranes but which also results in much lower hydrolysis resistance. Changing PBT into a more rigid polymer by using 2,6-naphthalene dicarboxylic acid instead of terephthalic acid results in compounds that exhibit excellent general properties but poorer low-temperature stiffening characteristics. 

Polymers are further defined based on the number of carbon atoms they contain. Thus, the PA based on 1,6-hexamethylene diamine and sebacic acid is named PA-6,10 and the polymer based on caprolactam, PA-6. Terephthalic and isophthalic acid units are coded T and I. Thus, PA-6,T represents the PA from hexamethylene diamine and terephthalic acid. 

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