Isophthalate/terephthalate ratio

Extensive literature is available on the effects of the variation of the isophthalate/terephthalate ratio upon the melting behavior and solubility characteristics of the polyesters of bis-phenol a2 5,6 properties of the tetrachlorobisphenol A... 

A seemingly contradictory set of objectives exist when one attempts to optimize solution stability of a methylene chloride solution of a polymer while requiring a fiber, from that polymer, to be resistant to perchlorethylene (Perclene) dry cleaning solvent. Initial evaluations of fibers show that the CAPE and BRAPE polyesters are attacked by dry cleaning solvent when the isophthalate/terephthalate ratios lie in the range of 50/50 to 80/20. These combinations, which are required for solution stability also lead to a maximum in Perclene susceptability. 

A convenient method of compositional designation uses molar percentages of ester and carbonate linkages coupled with the molar percentages of iso- and terephthalate units in the polymer. A 70% ester, 30% carbonate polyester carbonate with 60 parts of isophthalate and 40 parts of terephthalate is designated 70(60/40)30. Similarly, a standard PC resin is 0(0/0)100, and a polyarjlate resin composed of a 1 1 molar ratio of iso- to terephthalate units esterfied with bisphenol A is designated 100(50/50)0. 

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). 

Hajek et al. [173] have reported a detailed kinetic study of the solid phase decomposition of the ammonium salts of terephthalic and iso-phthalic acids in an inert-gas fluidized bed (373—473 K). Simultaneous release of both NH3 molecules occurred in the diammonium salts, without dehydration or amide formation. Reactant crystallites maintained their external shape and size during decomposition, the rate obeying the contracting volume equation [eqn. (7), n = 3]. For reaction at 423 K of material having particle sizes 0.25—0.40 mm, the rate coefficients for decompositions of diammonium terephthalate, monoammonium tere-phthalate and diammonium isophthalate were in the ratio 7.4 1.0 134 and values of E (in the same sequence) were 87,108 and 99 kJ mole-1. 

A PEIT of 50/50 (molar ratio) composition is synthesized by a two-step reaction sequence as follows. In the first step, 97.10 g (0.5 mol) dimethyl terephthalate (DMT), 97.10 g (0.5 mol) dimethyl isophthalate (DMI), 136.55 g (2.2 mol) 1,2-ethanediol, and zinc acetate dihydrate ester interchange catalyst (2.7 x 10 4% mass of the total amount of DMI and DMT mixture) are weighed into a threenecked flask fitted with a mechanical stirrer, a nitrogen inlet, and a condenser. The medium is stirred for 2.0-2.5 h at 180-210°C under nitrogen. Ninety-two percent of the theoretical amount of methanol is removed by distillation. In the second step, antimony acetate polycondensation catalyst and trimethyl phosphate thermal stabilizer (9.9 x 10-4 and 1.5 x 10 3% mass of the total amount of DMI... 

Mixed diacid chlorides with Terephthalate/isophthalate ratio of 50/50 was used during the reactions to inhibit the formation of crystalline ester segments b Composition in weight percent remaining part of the siloxane backbone is dimethylsiloxane ... 

For convenience, the letters T (terephthalic acid), I (isophthalic acid), H [50/50 cw/trarw-hexahydroterephthalic acid (1,4-cyclohexane-dicarboxylic acid)], and NPG [neopentyl glycol (2,2-dimethyl-l,3- propanediol)] are used to refer to the polyesters prepared from these intermediates thus, T50I(NPG) is the copolyester from neopentyl glycol and equimolar amounts (50/50 molar ratio) of terephthalic and isophthalic acids. 

In contrast, the intramolecular energy transfer in cyclooctene derivatives 63E-65E, which are tethered to benzoate, isophthalate, and terephthalate moieties through a (/ ,/ )-2,4-pentadiol linker, does not appear to be seriously affected by the steric bulk of 1-alkylation (Scheme 10) [50]. Upon irradiation at — 65°C, 63, 64, and 65 afforded ZJE ratios of 0.8,0.15, and 0.06, with diastereomeric excesses (des) of 33, 37, and 44%, respectively. 

Copolymers of isophthalic acid (IPA), terephthalic acid (TA), 1,3- bis(car-boxyphenoxy)-propane (CPP), or hexane (CPH), and fumaric acid (FA) were synthesized. Copolymers containing a mass fraction of 20% of a second aromatic monomer became soluble and melted at temperatures below 120°C. The polymers had a molecular weight of 35000. The copolymer properties were dependent on the nature and ratio of the comonomers in the polymer as seen in Table 9. Polymers of isophthalic acid containing a mole fraction of 10 to 90% fumaric acid or a mole fraction of 10 to 60% CPP were soluble, non-crystalline, and melted below 120°C. The copolymers of terephthalic acid (TA), however, were soluble only between the mole fraction range of 15 to 40% TA content as shown in Table 10. 

Obviously, there are a very large number of copolycondensation combinations of various glycols or diphenols with different dicarboxylic acids. For example, polymers from terephthalic acid, isophthalic acid, and bisphenol A in the molar ratios of 1 1 2 are offered commercially under the name poly-arylates. The mechanical properties of these amorphous polymers correspond to those of a typical engineering plastic. 

The hydroxyl containing polyester was synthesized from dimethyl terephthalate, isophthalic acidr trimellitic acidy and diethylene glycol or ethylene glycol using a butyl titanate catalyst. Ratios of reactants can be varied within limits to produce desired levels of hydroxyl content. 

Ester Single Tg I was Ardel D-lOO II was made from cyclohexane dimethanol and terephthalic acid/isophthalic acid (80-87 % tere) (Kodar A-150) and another copolymer with tere/iso ratio of 70/30 Robeson (1985)... 

The copolymers listed in Tables 1 and 2 comprise two series. In the first series (Table 1), a polysulfone oligomer of 6,000 g/mole was utilized. The sulfone-ester composition was held constant at 50-50 weight ratios while the composition of the polyester block itself was varied from 100% isophthalate to 100% terephthalate. At the extremes of composition (Samples I-l, 1-2, 1-7), the... 

The preferred aromatic diphenol based on current commercial offerings is bisphenol A the aromatic dicarboxylic acid is proportioned between isoph-thalic acid and terephthalic acid (eq. (1)). The election of a particular isophthalic acid/terephthalic acid ratio is influenced by both the commercial manufacturing process and market orientation (1). The ratio of x, y in the product of equation (1) is close to one for U-Polymer, produced by Unitika, the only current commercial polyarylate. 

A PAN copolymer containing itaconic acid (PAN-I) was synthesized by emulsion polymerization at the Research Institute of Synthetic Fibers (Tver, Russia) at feed ratio of 98.5/1.5 w/w acrylonitrile/itaconic acid, and has an intrinsic viscosity (dimethylsulfoxide, 25°C) of 2.06 dl/g. An aromatic polyamide (PA) derived fix>m terephthalic and isophthalic acid dichlorides (tere/iso ratio of 85/15 w/w) and 9,9-(4-aminophenyl) fluorene was synthesized at the Nesmeyanov Institute of Organoelement Compounds, and has [r ]=0.98 dl/g (N-methylpyrrolidone, 25 C). Co2(CO)g was recrystallized from pentane, while DMF (Aldrich) was used as received. 

APE, CAPE and BRAPE — show solubility which varies with the ratio of iso/terephthalate units. In all cases the solubility is a maximum at a 60-70% (molar) isophthalate level. The 100% isophthalate or terephthalate compositions are all insoluble in most of the useful solvent systems. In addition to the effect of the acid composition there is an effect on solubility from the substitution on the bisphenol A moiety, with the BRAPE composition showing the lowest degree of solubility. 

McKee et al. (2004b) reported that the fiber diameter d for electrospinning of polyfethylene terephthalate-co-ethylene isophthalate) copolymers from CHCfi/DMF (70/30) scaled with the ratio c/cj d c/c f ). 

This equation does not take into account in a visible way the conformational restrictions (although they can be partly accounted for, hidden in the value of the chararteristic ratio CJ. Conformational consttaints are espedally important for rigid chains. For instance, the equilibrium concentration of cydics in poly(butylene isophthalate) is 3 rimes higher than in poly(buty-lene terephthalate), because the former has abent rigid stmcture. ... 

As a member of the nylon family, it is a semicrystalline material composed from a diacid and a diamine. However, the diacid portion contains at least 55% terephthalic acid (TPA) or isophthalic acid (IPA). TPA and IPA are aromatic components which serve to raise the melting point and glass transition temperature, and generally improve chemical resistance versus standard aliphatic nylon polymers. The structure of the polymer depends on the ratio of the... 

The high performance LCP (HP-LCP) was made of copolyester of 2-hydroxy-6-naphthoic acid (HNA), hydroquinone (HQ), 2,6-naphthalene dicarboxylic acid (NDCA) and terephthalic acid (TA). HNA and NDCA were selected as naphthalene moiety because of imparting hydrolysis resistance to copolyester. Isophthalic acid (lA) was not used as one of the components because it was observed that the lA moiety, a bent-shaped monomer, deteriorates hydrolysis resistance. The ratio of HQ was specifically selected for adjusting the target melt viscosity of the copolymer. The level of heat resistance depends mainly on the ratio of both TA and HQ. Although many TLCPs have been developed and each commercial TLCP has a different combination of monomers, the composition of the HP-LCP... 

Fig. 3. Post yield stress drop (PYSD) versus tan 5 of at SCC for bisphenol-A PC, polysulfone, and PEC resins of various ester/caibonate (E/C) ratios and terephthalic/isophthalic (T/I) ratios (from lef. 4).

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