Hydroxylated polyesters applications

Curing of oil-modified alkyds with polyisocyanates results in faster drying, better chemical resistance and abrasion resistance. Hydroxylated polyesters crosslinked with both aromatic and aliphatic polyisocyanates are finding extensive applications in high-quality maintenance finishes. These two-component finishes cure at ambient temperature. Aliphatic urethane types are used on aircraft, rail and other transportation equipment where excellent gloss retention and... 

It should additionally be noted that a number of the paths of the schemes above have received some confirmation in a number of literature reports dealing with the photolysis and photo-oxidation of other polyesters [32-35], Because these reports investigated poly(butylene terephthalate) (PBT), poly(ethylene naphthalate) and poly(butylene naphthalate), however, they may not have direct application to understanding of the processes involved in PET and PECT and so have not been discussed in this present chapter. All do contain support for the formation of radicals leading to CO and C02 evolution, as well as the hydrogen abstraction at glycolic carbons to form hydroperoxides which then decompose to form alkoxy radicals and the hydroxyl radical. These species then were postulated to undergo further reaction consistent with what we have proposed above. 

Together, antifreeze, PET, and polyester polymers account for about 98% of the ethylene glycol produced in the United States. It is also used sometimes as a deicer for aircraft surfaces. The two hydroxyl groups in the EG molecule also make EG suitable for the manufacture of surfactants and in latex paints. Other applications include hydraulic brake fluid, the manufacture of alkyd resins for surface coatings, and stabilizers for water dispersions of urea-formaldehyde and melamine-formaldehyde The hygroscopic properties (absorbs moisture from the air) make EG useful as a humectant for textile fibers, paper, leather, and adhesives treatment. 

The primary and secondary alcohol functionalities have different reactivities, as exemplified by the slower reaction rate for secondary hydroxyls in the formation of esters from acids and alcohols (8). 1,2-Propylene glycol undeigoes most of the typical alcohol reactions, such as reaction with a free acid, acyl halide, or acid anhydride to form an ester reaction with alkali metal hydroxide to form metal salts and reaction with aldehydes or ketones to form acetals and ketals (9,10). The most important commercial application of propylene glycol is in the manufacture of polyesters by reaction with a dibasic or polybasic acid. 

The selection of a stationary phase suitable for the GC analysis of all amino acids seemed to be the main problem hindering the wider use of these derivatives, which were always applied to a limited number of amino acids only. For the separation of TFA-amyl esters about 100 stationary phases have been tested, most of which were rejected owing to the decomposition of the acyl derivatives of hydroxyl and thiol groups that proceeds on some stationary phases with Tyr, Ser, Hypro, Thr and CysH. The application of 25% DECS led to the elution of only eight derivatives of amino acids out of thirteen that were analysed [225], The polyester PEGA and the silicones QF-1 and MS-710 [197,227, 228] were reported as the most suitable liquid stationary phases. For the analysis of... 

Unsaturated polyesters having hydroxyl groups can be prepared by the reaction of glycols, maleic anhydride and dicarboxylic acids in more than the stoichiometric amount of glycols/carboxylic acids (13, 34). Edwards discussed the application of isophthalic unsaturated polyester urethane hybrids in conventional molding techniques (13). He also applied the hybrids to foamed products (21). Vinyl esters can be prepared by the reaction of bisphenol A with glycidyl methacrylate (21). 

A number of organotin polyesters, polyamides, polythiols, polyethers, and polyaminoesters have been synthesized from dialkyltin halides with dicarboxylic acids, diols, diamines, dithiols, urea, thiourea, amino acids, and hydroxyl acids involving polycondensation reactions. These polymers have potential applications as thermostabilizers for PVC. 

The hydroxyl terminated polybutadienes lead to PU with physico-mechanical properties significantly lower than those of PU based on polyether or polyester polyols. The nonpolar polymeric chain and the extraordinary hydrophobicity mean that hydroxy terminated polybutadienes are used for special applications, due to their excellent electrical insulation properties which are equal or superior to epoxies or silicone elastomer systems. The hydrolytic stability of PU elastomers derived from hydroxyl terminated polybutadiene is superior to the majority of other types of PU. Thus, some specific applications of... 

Polyurethane Enamels. Small volumes of this enamel type are used in applications for which the temperature does not rise above approximately 105 C. These enamels are made from hydroxyl-bearing polyesters and blocked isocyanates. During the heating cycle in the enameling process the isocyanates become unblocked and react with hydroxyl groups of the polyesters to form a cross-linked polyurethane film. Wires so insulated can be directly soldered, without prior removal of the polyurethane insulation. 

Two-Package Polyol Urethane Coatings (ASTM Type 5). Two-package polyol urethane coatings consist of isocyanate-terminated adducts of polymers that are cured by reaction with di- or polyfunctional hydroxyl-containing materials. The latter may consist of low- to medium-weight polyols with a polyester, polyether, polyether urethane, or castor oil backbone. When the two components (OH- and NC0-) are mixed together, they have only a limited pot life. Therefore, the components are mixed prior to application. Catalysts may be used to speed up the cure either for room temperature or oven cure. 

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