Poly „-oxybenzoic acid

The -hydroxybenzoic ( -oxybenzoic) acid has been extensively used at polymeric synthesis for the improvement of thermal stability of polymers for the last years [18, 19]. The aromatic polyester ECONOL, homopolymer of poly -oxybenzoic acid, possesses the highest thermal resistant among the all homopolymeric polyethers [20] and attracts attention for the industry. 

Several methods for the producing the poly -oxybenzoic acid have been proposed [20,23-30], which are based of the high-temperature poly-... 

Materials and Processing. Copolyesters of poly(ethylene terephtha-late) (PET) and para-oxybenzoic acid (FOB) were supplied by the Tennessee Eastman Corporation. Past work Indicates the copolyesters form thermotropic liquid crystalline phases at compositions containing more than 30 mole% POB (26,27,28). The composition of the copolyester studied here contains 60 mole% POB. Quiescent liquid crystalline films were made by compression molding the copolyester at 210, 230, 255, and 285 C, and followed by a quench Into Ice water, ambient air, or cooled In the press with the power off. Film thicknesses ranged between 0.05-0.15 mm. Another sa(q>le of the 40/60 PET/POB copolyester was melted at 270 °C In a Mettler hot stage, manually sheared between glass slides, and then ambient air cooled. 

The mixing of melts poly 4,4 -oxybenzoic acid/polyethyleneterephthalate was studied in Ref. [Ill] the kinetic characteristics of the mix became incompatible at leetherification. 

POB, see poly(4-hydroxybenzoic acid), as well as polyoxybenzoate POBcoON, see poly(oxybenzoate-co-oxynaphthoate)... 

In 1973, the Federal Trade Commission modified the generic definition of polyester to include in the polyester category materials that previously were polyester ethers or benzoate polyesters. As a result, the fiber known as poly (ethylene oxybenzoate) or PEB and manufactured under the trade name A-Tell in Japan came to be known as polyester. This material is made by reacting parahydroxy-benzoic acid and ethylene oxide to give... 

Copolyesters of poly(ethylene terephthalate) and 4-acetoxybenzoic acid (PET / oxybenzoate) were synthesized by Jackson et al. through high temperature melt transesterification. However intricate details pertaining to the polyesterification kinetics have remained unexamined. In this system, insertion of 4-oxybenzoate moieties, with stiff rod like conformations, into flexible PET chains fosters the development of thermotropic character within a definite range of copolyester composition. 

Copolycondensation of dicarboxylic acids, diacetated of bisphenols and/or acetated of aromatic oxy-acids ( -oxybenzoic one) with poly-ethyleneterephthalate. 

Stnctnrally, the simplest of the wholly aromatic polyesters are those based on hydroxybenzoic acids, with poly(p-oxybenzoate) being the most commonly encountered ... 

Of special importance is in this case that the backbone of the copolymer can change chemically by trans-esterification (see Fig. 3.47). In fact, heating poly(ethylene terephthalate) and acetoxybenzoic acid in the melt is a common synthetic route to PETcoOB. The inclusion of oxybenzoate groups makes poly(ethylene terephthalate) increasingly stiffer (see Fig. 1.50). In POBcoON, oxynaphthoate adds an additional off-set of the large zig-zag of the benzoate. As a result of this chain stiffening, the PETcoOB with more than 30 mol-% oxybenzoate shows an anisotropic melt, as for a nematic main-chain liquid crystal (see Fig. 5.136) and the system POBcoON has a mesophase character over the whole concentration range. 

Poly(p-oxybenzoate) n. Poly(4-hydroxy-benzoic acid). 

An understanding of the melt polyesterification kinetics is a must to economise on the process productivity and to improve the polymer properties. There is no published literature on the melt polyesterification kinetics of PBT, HQDA and TA. Kinetic investigation of copolymerisation between PET and 4-acetoxy benzoic acid (PET/OB) did not reveal precipitation of poly (4-oxybenzoate). Here we explore the kinetics of a three component system, wherein many parallel reactions take place simultaneously. Homopolymerisation between HQDA and TA lead to a rigid rod system. 

There has been no evidence of kinetic studies of melt transpolyesterification of PBT-TA-HQDA ternary system. An earlier study relating to copolyesterification of PET and 4-acetoxy benzoic acid did not manifest precipitation of poly(4-oxybenzoate) °. This work is an attempt to investigate the melt reaction behaviour of the PBT/HQDA/TA system. The work is presented as follows A simple reaction sequence is suggested to outline the dominant steps involved. The major reactions, which lead to acetic acid production, are taken into account in the kinetic analysis. Simple second order kinetics is found to be effective for each of the steps significant to the acetic acid production. The correctness of this procedure is justified by experimental observations. Finally, physico-chemical characterization of the copolyesters are considered. 

A combined main-chain/side-chain liquid-crystalline polymer can be s)mthesized, which comprises of poly[(phenylsulfonyl-p-phenylenene 1,4-tetramethylene bis(oxybenzoate)] as the main-chain backbone and 8-[(4-cyano-4 -phenyl)oxy]octanoic acid as the... 

All of the reactions listed above can be equally applied to the preparation of aromatic copolyesters from almost any combination of hydroxyacids, dicarboxylic acids and biphenols of the types listed in Table 3. In general, the copolymers so obtained are random or statistical in composition. Furthermore, the acidolysis reaction has been successfully applied to preparation of random copolyesters by interchanging monomers and high molecular weight polymers, most notably in the preparation of poly(ethylene terephthalate-co-oxybenzoate) by the insertion reaction of /7-acetoxybenzoic acid with preformed poly(ethylene terephthalate), as follows... 

The term solid state polycondensation (SSP) simply says that chain growth by condensation steps occur under conditions, where at least one reaction partner exists in the solid state. As discussed below, SSP encompasses a broad variety of condensation reactions and substrates. Seemingly, the first example of a SSP (but not recognized as such) was the synthesis of poly(4-hydroxybenzoic acid), poly(4-oxybenzoate) by dry distillation of 4-hydroxybenzoic acid (see Chap. 2, Refs. [64—66]). A more detailed discussion of syntheses of poly(4-hydroxybenzoic acid) will we presented in Sect. 14.3. The first section is dedicated to SSPs of peptide esters which were also described for the first time before World War 1. 

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