Isophthalic acid, polyesters from

Isophthalic acid s main use is for producing polyesters that are characterized hy a higher abrasion resistance than those using other phthalic acids. Polyesters from isophthalic acid are used for pressure molding applications. 

Wholly aromatic hyperbranched polyesters based on 3,5-dihydroxyisophthalic acid can be prepared either from bis(acetoxy)isophthalic acid or from its silylated derivative (Scheme 2.67). 

From these data it is apparent that the resin in the body filler is a styrenated diethylene glycol-isophthalic acid polyester cross-linked with maleic anhy-dride/fumaric acid and modified with adipic acid to give the resin flexibility. 

Processes have been developed separating pure metaxylene from other Cj aromatics.Metaxylene is a raw material for the manufacture of isophthalic acid. The major outlets for the acid are in the synthesis of unsaturated polyester and alkyd resins, and for the production of isophthalic esters (plasticizers). 

The primary crystalline polymer based on CHDM is the terephthalate, poly(1,4-cyclohexylenedimethylene terephthalate) (PCT). This polyester was originally developed for fiber applications but has since found wider utility as a reinforced polymer for injection molding and (when copolymerized with a small amount of isophthalic acid) as a material for crystallized food packaging trays. The key property of PCT which sets it apart from other thermoplastic polyesters in these latter applications is its melting point. 

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. 

Ester-based cascades (e.g., 107) have been prepared[77 80i by using 5-(tert-butyldime-thylsiloxy)isophthaloyl dichloride (108), which was synthesized in high yield from 5-hydroxy-isophthalic acid (Scheme 5.26). The dendron wedges were prepared by treatment of siloxane 108 with phenol to give bis(aryl ester) 109, which was hydrolyzed, or desilylated (HC1, acetone), to generate a new phenolic terminus. Treatment of this free phenolic moiety with monomer 108, followed by hydrolysis, afforded the next tier (110). Repetition of the sequence followed by reaction of the free focal phenols with a triacyl chloride core, (e.g., 86), afforded the fourth tier dendrimer 107 of the polyester aryl series. It was noted that the choice of base (N, A-dimethylaniline) used in the final esterification was critical, since with pyridine bases (pyridine or 4-(dimethylamino)pyridine) facile transesterification resulting in branch fragmentation occurred. 

Branched saturated polyester from adipic acid, phthalic anhydride, neopentyl glycol and trimethyl olpropane was mixed with BPA/DC solution in 2-methoxyethanol/ xylene and diluted with ethyl acetoacetate. A thermohardening coating with high hardness and good adhesion on steel was obtained [136]. A similar coating composition consists of BPA/DC and a polyester from adipic and isophthalic acid, trimellitic anhydride, neo pentyl glycol and trimethylolpropane [137, 138]. 

There is a large body of patent literature and a growing amount of scientific literature on blends of polycarbonate with various crystallizable polyesters. The latter would include poly (ethylene terephthalate), poly-(butylene terephthalate), polycaprolactone, and certain copolyesters derived from mixtures of terephthalic acid and isophthalic acid co-reacted with 1,4-cyclohexanedimethanol (79, 80, 81,82). As shown recently, some of these mixtures form miscible blends although the polyester possesses the possibility of crystallizing. The number of patents on such systems indicates a degree of commercial interest. 

Aromatic polyesters formed from 4,4 -isopropylidenebis(2,6-dibromophenol), from various analogous bisphenols differing in the character of the bridge [94] or from 2,2 -bis[3,5-dibromo-4-(2-hydroxyethoxy)phenyl]propane and terephthalic or isophthalic acids possess [194] good thermal resistance and flame retardance. 

A whole series of high-performance polyester LCPs was introduced in 1985. They were assembled from p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid. Polyarylates (PARs) - amorphous phenolic esters derived from aromatic dicarboxylic acids (mixtures of terephthalic acid and isophthalic acid) and biphenols such as bisphenol A - are produced by Amoco (Ardel ), Celanese (Durel ) and DuPont (Arylon ) at a volume of approx. 2000 t/a. 

Polymer concretes show excellent mechanical properties and chemical resistance compared with conventional cement concretes. Polymer concretes can be cured quickly by the use of curing agents. Thus, the applications of polymer concretes are being increased. One of the popular polymers for polymer concretes is unsaturated polyester (UPE) resin. The properties of UPE resin can be modified by changing its molecular features. For the synthesis of the resin, phthalic anhydride or isophthalic acid as well as maleic anhydride can be employed to modify the mechanical properties or hydrothermal resistance. Terephthalic acid which is also used for the synthesis of poly ethylene terephthalate (PET) enhances the thermal resistance of the cured UPE resin. However, the synthesis of unsaturated polyester resin from terephthalic acid is difficult. One method to synthesize unsaturated polyester from terephthalic acid is the use of recycled PET. 

Another possibility for obtaining imide modified thermoplastic polyesters was to use as a monomer the hydroxy acid made from trimellitic anhydride and aminoethanol. Such a poly(ester-imide) was claimed for injection molding [240]. For the same use, poly(ester-imide)s containing aminophenol/trimellitic anhydride [241],imidised polyfbutylene terephthalate) [242] and a wholly aromatic poly(ester-imide) made from trimellitic anhydride, p-aminobenzoic acid, p-acetoxybenzoic acid, diacetoxybiphenyl and terephthalic and isophthalic acids are known, which showing optical anisotropy [243]. 

The unsaturated polyester prepolymers are obtained from the condensation of polyhydric alcohols and dibasic acids. The dibasic acid consists of one or more saturated acid and/or unsaturated acid. The saturated acid may be phthalic anhydride, adipic acid, or isophthalic acid, while the unsaturated acid is usually maleic anhydride or fumaric acid. The polyhydric alcohols in common use include glycol (such as ethylene glycol, propylene glycol, diethylene glycol), glycerol, sorbitol, and pentaeiythritol (Equation 5.1). 

FigureT. DSC investigations of three different aromatic homopolyesters (a) LC polyester composed of chlorohydroquinone and terephthalic acid [poly(ClHQ/TA)], (b) LC polyester composed of chlorohydroquinone and 2,5-thiophene dicarboxylic acid [poly(ClHQ)/ThA], (c) polyester composed of chlorohydroquinone and isophthalic acid [poly(ClHQ/lA)] (adapted from [12]).

In addition to bio-based polyesters such as poly(lactic acid) (PLA), polyhydroxyalkanoates (PHAs), and poly(ethylene furanoate) (PEE), all based upon biomass-derived building blocks that have a structure different from today s commercial petrochemical-based polyesters, biobased polyesters can be developed having an identical structure to well-known petrochemical based polyesters. A very important class of such drop-in type bio-based polyesters are represented by polyesters based upon either isophthalic acid or terephthalic acid, such as PET,... 

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