Saturated Diacids

The most commonly used saturated acids are listed in Table F.6.6. 

All these acids are solids at room temperature. Their solubility in water decreases with increasing molecular mass. 

At room temperature, a solution of 10% oxalic acid leads to uniform dissolution of 0.10 mm per year. 

The other acids, as a solution or in concentrated form, only have an insignificant action on aluminium. The dissolution rate increases with temperature. For oxalic acid, it is multiplied by four between 20 and 100 °C. 

These acids are transported and stored in aluminium vessels. 

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Fumaric and itaconic acids are also used as the diacid component. Most reaction formulations involve a mixture of a saturated diacid (iso- and terephthalic, adipic) with the unsaturated diacid or anhydride in appropriate proportions to control the density of crosslinking (which depends on the carbon-carbon double-bond content of the prepolymer) for specific applications [Parker and Peffer, 1977 Selley, 1988], Propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, and bisphenol A are also used in place of ethylene glycol as the diol component. Aromatic reactants are used in the formulation to improve the hardness, rigidity, and heat resistance of the crosslinked product. Halogenated reactants are used to impart flame resistance. 

The three basic polymorphic forms shown in Figure 2, which may apply to the saturated monoacid TAGs, are largely modified when the shape of a TAG molecule becomes more heterogeneous. For example, TAGs containing unsaturated fatty acid moieties or saturated diacid moieties exhibit two p or p forms. In other cases, p does not occur and p becomes most stable with the highest T instead. These properties will be discussed in Section 3. 

Atomic-Level Crystal Structures of p Form We discuss crystal structures of the p forms of two saturated diacid TAGs, C10C12C10 (41) and C16C16C14 (42). Both are the first p polymorphs of TAG that have been analyzed at the atomic level by using single crystals. Two different types of the p structures were found as revealed in the unit cell parameters shown in Table 3. 

Aliphatic polyanhydrides synthesized lirom saturated diacid monomers are crystalline, melt at tanperatuies below 100 °C, and are soluble in chlorinated hydrocarbons. They are degraded and eliminated from the body within weeks [39],... 

This section in a similar way as the previous one summarizes a number of studies on the adsorption saturated and unsaturated diacids to (oxy)(hydr)oxide minerals. The chemical speciation (in terms of the number of species in solution) becomes more complex for these compounds, which concomitantly enhances the possibilities of the diacids to form surface complexes of different stoichiometries in terms of bonding and proton balances. The diacids addressed are summarized in tables 3 (saturated diacids) and 4 (imsaturated diacids). The remainder of the section discusses in some detail published findings from ATR-FTIR spectroscopy. 

An unsaturated polyester resin has two primary components, a polyester containing polymerisable double bonds and a copolymerisable solvent monomer, of which the most commonly used is styrene. Unsaturated polyesters are made by esterification of glycols with mixtures of maleic anhydride and saturated diacids (Structure 9.1). The term alkyd is used to describe low-molecular-weight polyesters, where molecular weight is broadly... 

The double bond in the maleic acid is inert toward condensation polymerization. Note that the degree of unsaturation (average number of double bonds per repeating unit) could be varied from zero to one (as it is here) by employing mixtures of a saturated diacid, for example, phthalic anhydride (III), and the maleic anhydride to form copolyesters with saturated and unsaturated repeating units ... 

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