Polyester dibasic acid type

Unsaturated Polyesters. Unsaturated polyesters are produced by reaction between two types of dibasic acids, one of which is unsaturated, and an alcohol to produce an ester. Double bonds in the body of the unsaturated dibasic acid are obtained by using maleic anhydride or fumaric acid. 

Meanwhile, Rohm and Haas introduced the first of the polymeries - polyesters based on the reaction of a dibasic acid with a glycol and with a monohydric alcohol or monobasic acid as chain terminator(j>). These plasticizers were developed as highly permanent, extraction and migration resistant types for specialty applications. 2-Ethylhexanol and isodecyl alcohol are examples of monohydric alcohols used as chain terminators in today s polymeries. 

In order to obtain the high molecular weight required for commercial application, the reactive groups in linear condensation pol3rmer intermediates must be very close to an exact balance. In the three commercially produced types of polymer, this balance is achieved in different wajrs. The three systems are polycaprolactam, polyamides (from dibasic acids and (fiamines), and polyesters (from glycols and dibasic acids). 

Different types of chemical compounds such as vegetable oils, fatty adds, dibasic acids and anhydrides, dihydroxyamine and catalysts are required for the preparation of vegetable oil-based poly(ester amide)s. The methods of resinification or polymer formation are similar to those of vegetable oil-based polyesters, as discussed in the earlier chapter (Chapter 4). 

Unsaturated polyester resins are complex polymers resulting from a crosslinking reaction of a liquid unsaturated polyester with vinyl-type monomers, most often a styrene monomer. The unsaturated polyester is formed via the condensation reaction of an unsaturated dibasic acid or anhydride, a saturated dibasic acid or anhydride, and a polyfunctional alcohol [32]. 

In this compilation common usage is more nearly followed by naming the source materials, or monomers, and the name of the functional group, if any, incorporated into the chain backbone. Since the same polymer can often be formed in a variety of ways, from different source materials, it is necessary to specify arbitrarily the dass of source materials from which each functional type of polymer shall be named. For example polyesters shall be named according to the dibasic acid and diol from which they could have been formed, even though some other route to the polymer may actually have been used. They are indexed only under the name of the acid. The source materials chosen for naming the various types of polymers are tabulated bdow. 

A somewhat analogous type of structural isomerism occurs in certain polymers formed by condensation of two co-reagents, for example the polyesters of 1,2-propanediol with dibasic acids, or polyamides of 3-methylhexanedioic acid. Two different structural units are possible ... 

In addition to a reaction diols with dibasic acids, most polyester polymeric plasticizers, as mentioned above, are end-capped. Organic monobasic end caps are normally saturated fatty acid types. Alcohol end caps are usually in the Cg to Cio range. For several appheations, it is desirable to finish the polymeric plasticizer and reduce the residual acid or hydroxyl content essentially to zero. Acetic anhydride is typically used to eliminate hydroxyl content. 

Unsaturated polyesters are produced via a condensation reaction between a dibasic organic acid or anhydride and a difunctional alcohol. The prepolymer is then dissolved in an unsaturated monomer, such as styrene. To initiate a cross-linking, a free radical source such as an organic peroxide is added to the liquid resin. The types and ratio of components used to manufacture the prepolymers, the manufacturing procedure, and the molecular weight of the prepolymer will determine the properties of the cured polyester. 

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