Polyesters from anhydrides

The reaction of glycols with either maleic or phthalic anhydride has been commercially applied to the preparation of polyesters. The reactions involve two distinct steps with the second, the esterification of the free carboxyl group, being slower, viz. 

More usually, phthalic anhydride is reacted with a polyfunctional material such as glycerol to form a network polyester (a glyptal). This class of polymer, modified with monofunctional additives and known as alkyd resins, is very important in the paint and plastics industry. Consequently most of the theoretical studies have been concerned with the formation of infinite networks ( microgel ) and the distinction between this and the so-called gel-point [75]. 

Pentaerythritol reacts with phthalic anhydride at a rate roughly five times greater than with tetrachlorophthalic anhydride the respective activation energies [32] are 24.0 and 27.3 kcal mole . Other polyesters based on phthalic anhydride have been surveyed [32]. 

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Uyama, H., Wada, S., Fukui, T., and Kobayashi, S. (2003) Lipase-catalyzed synthesis of polyesters from anhydride derivatives involving dehydration. Biochem. Eng. J., 16 (2), 145-152. 

Polyesters from polybasic acids and polyhydric alcohols. Alkyd resins. The condensation of polyhydric alcohols and polybasic acids or anhydrides leads to polj esters known as alkyd resins. The most common member of the group is a glycerol - phthahc acid polymer, and this has led to the term glyptal resins being frequently apphed to the whole group. 

Lipase-catalyzed synthesis of polyesters from cyclic anhydrides and oxi-ranes was reported. The polymerization took place by PPL catalyst and the molecular weight reached 1 x 10" under the selected reaction conditions. During the polymerizahon, the enzymatically formed acid group from the anhydride may open the oxirane ring to give a glycol, which is then reacted with the anhydride or acid by lipase catalysis, yielding the polyesters. 

How can you make a polyester and a polyamide Objectives Prepare a polyester from phthalic anhydride and ethylene glycol. Prepare a polyamide from adipoyl chloride and hexamethylenediamine. phthalic anhydride (2.0 g) sodium acetate (0.1 g) ethylene glycol (1 mL) 5% adipoyl chloride in cyclohexane (25 mL) 50% aqueous ethanol (10 mL) 5% aqueous solution of hexamethylenediamine (25 mL) 20% sodium hydroxide (NaOH) (1 mL) scissors copper wire test tube test-tube rack 10-mL graduated cylinder 50-mL graduated cylinder 150-mL beakers (2) ring stand clamp Bunsen burner striker or matches balance weighing papers (2)... 

Polyethylene and a peroxide initiator were added to the usual BPA/DC-BMI-epoxide resin composition. The use of unsaturated polyesters from tetrabromo-phthalic anhydride, maleic anhydride and ethylene glycol as well as of other fire retardants was also described [99]. 

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]. 

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. 

The Introduction of clnnamoyl groups as lateral substituents gives rise to valuable photo-cross-linkable polymers. The transformation of preexisting polymers, especially by esterification, has proved to be the most adequate technique. Cellulose, poly-condensation products of epichlorhydrine and 2,2(4,4 -dihydroxy-diphenyl)propane, polyesters from glycerin and phthallc anhydride... 

Polyester thermosets are based on partly unsaturated linear polyester from the step-growth polymerisation of propylene glycol, phthalic anhydride and maleic anhydride. 

Some glycerine or trimethylolpropane may be used to introduce branching structures within the polyester backbone. Phthalic anhydride may also be used to increase hardness and water resistance. Inexpensive terephthalic add-based polyesters from recycled poly-ethyleneterephthalate (PET) resins have more recently become popular. 

The condensation of acid anhydrides and diols. Similar side reactions can occur as in method 1. The method is used commercially to synthesize unsaturated polyesters from maleic anhydride and ethylene glycol ... 

The polyester from Problem 29.19 can be mixed with additional phthalic anhydride (0.5 mole of phthalic anhydride for each mole of 1,2,3-propanetriol in the original polyester) to form a liquid resin. When this resin is heated, it forms a hard, insoluble thermosetting polyester called glyptal. 

Just as simple esters and amides can be made by condensation reactions, polyesters such as Dacron and Mylar are made by reacting diols with dicarboxylic acids (Figure 13.15 A). Similarly, polyamides such as nylon form from amines and carboxylic acids. Starting from anhydrides and amines, polyimides can be formed. These structures tend to be extremely stable, and so are valuable in high temperature applications. 

Condensation polymerization of glycols with tartaric acid results in poly(alkylene tartrate)s [42 4]. The hydroxylated polyesters from C2 and C4 are hydrophilic and water soluble and those from C6 and higher glycol are water insoluble with increase in hydrophobicity with increasing size of glycols. Crosslinkable unsaturated poly(alkylene tartrate)s are obtained by adding maleic anhydride to the polymerization of glycols with tartaric acid (4) [45]. Poly(tartrate) was obtained from the condensation of tartaric acid ketal with tartaric acid diacetate [46]. 

Fischer, R. F, Polyesters from epoxides and anhydrides,/. Polym. Sci., 44, 155,1960. Bouillon, Nelly, Pascault,/. R, and Tighzert, L., Epoxy prepolymers cured with boron trifluoride amine complexes. 1. Influence of the amine on the curing, Maferomol. Chem., 191, 1403, 1990. 

Fischer RF. Polyesters from expoxides and anhydrides. J Polym Sci 1960 44 155-172. 

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