Hydroxy-terminated polyether

In a similar way, polyester block copolymers were obtained by reacting acid chloride-terminated polyesters with hydroxy-terminated polyethers,401 or by reacting polyester-containing polymer mixtures with coupling agents such as diisocyanates.402... 

Acid anhydride-diol reaction, 65 Acid anhydride-epoxy reaction, 85 Acid binders, 155, 157 Acid catalysis, of PET, 548-549 Acid-catalyzed hydrolysis of nylon-6, 567-568 of nylon-6,6, 568 Acid chloride, poly(p-benzamide) synthesis from, 188-189 Acid chloride-alcohol reaction, 75-77 Acid chloride-alkali metal diphenol salt interfacial reactions, 77 Acid chloride polymerization, of polyamides, 155-157 Acid chloride-terminated polyesters, reaction with hydroxy-terminated polyethers, 89 Acid-etch tests, 245 Acid number, 94 Acidolysis, 74 of nylon-6,6, 568... 

Hydroxy-terminated polyester (HTPS) is made from diethylene glycol and adipic acid, and hydroxy-terminated polyether (HTPE) is made from propylene glycol. Hydroxy-terminated polyacetylene (HTPA) is synthesized from butynediol and paraformaldehyde and is characterized by acetylenic triple bonds. The terminal OH groups of these polymers are cured with isophorone diisocyanate. Table 4.3 shows the chemical properties of typical polymers and prepolymers used in composite propellants and explosives.E4 All of these polymers are inert, but, with the exception of HTPB, contain relatively high oxygen contents in their molecular structures. 

In order to avoid the use of lead compounds on environmental grounds, lithium fluoride (liF) has been chosen to obtain super-rate burning of nitramine composite propellants.P7281 Typical chemical compositions of HMX composite propellants-with and without liF are shown in Table 7.4. The non-catalyzed HMX propellant is used as a reference pyrolant to evaluate the effect of super-rate burning. The HMX particles are of finely divided, crystalline (3-HMX with a bimodal size distribution. Hydroxy-terminated polyether (HTPE) is used as a binder, the OH groups of which are cured with isophorone diisocyanate. The chemical properties of the HTPE binder are summarized in Table 7.5. 

Typical examples of HCP are hydroxy-terminated polybutadiene (HTPB), car-boxy-terminated polybutadiene (CTPB), hydroxy-terminated polyether (HTPE), hydroxy-terminated polyester (HTPS), and hydroxy-terminated polyacetylene (HTPA). The physicochemical properties of various types of HCP are described in Section 4.2.3. 

The first step in formulating a urethane sealant is to prepare what is commonly called the prepolymer, typically by reaction of a hydroxy-terminated polyether with a stoichiometric amount of a diisocyanate. Each hydroxy group reacts with one end of every diisocyanate molecule. 

Ahad, E. (1990) Process for the preparation of alkyl azide substituted hydroxy terminated polyethers. US Patent 4,891,438 Chem. Ahstr., (1988) 109,171140u. 

There are a number of syntheses leading to the formation of urethane polymers. However, the most important commercial route is the isocyanate addition polymerization, the reaction between di- and polyfunctional hydroxyl compounds such as hydroxy-terminated polyethers or polyesters and di- or polyisocyanates. When difunctional reactants are being used, linear polyurethanes are produced and the reaction can be schematically represented as follows ... 

Polyamide-polyether block copolymers can be formed by a variety of techniques. One of them consists of initial preparation of amine-terminated polyethers. This can be done by reacting hydroxy-terminated polyethers with acrylonitrile and then reducing the nitrile groups to amines [429] ... 

In general, hydroxyethylation processes with ethylene carbonate generally result in a mixture of products. The initially formed bis(2-hydroxyethyl)isosorbide may further react with ethylene carbonate to form higher hydroxy terminated polyethers. The formation of such higher polyethers may be controlled by the amoimt of added ethylene carbonate, and the nature of the catalyst system (37). Further, the raw bis(2-hydroxyethyl)isosorbide may be purified by distillation. 

Recently, impact modifiers have been developed for plastics other than PVC. Polybutylene and other olefinic thermoplastic elastomers, for example, are being used to enhance the processability, toughness, and heat stability of polypropylene film. Hydroxy-terminated polyethers are being used to increase the impact resistance of polystyrene. Other conunon applications are polycarbonate, polyurethane, thermoplastic polyester, epoxy, and polysulfone. 

Hydroxy-terminated polyethers have now assumed a dominant role in the commercial production of polyurethanes. The most widely used polyethers are derivatives of propylene oxide and these polymers are described in Section 8.4.3.1. Linear, glycol-initiated propylene oxide polymers and propylene oxide-ethylene oxide block copolymers find some use in the preparation of elastomers. Polyether triols of relatively high molecular weight (about 3000) are extensively used for the production of flexible foams whilst polyols of low molecular weight (about 500) are used for rigid foams and surface coatings. Poly(oxytetramethylene) glycols prepared from tetrahydrofuran (Section 8.4.6) are used for the preparation of elastomers and spandex fibres. 

Polyurethane foams typically have a segmented structure of hard and soft segments. The hard segments consist of diisocyanate and chain extender units. The soft segments are hydroxy-terminated polyether or polyester-based polyols. 

The synthesis of oxetanes substituted at the 3-position with fluoroalkyloxy groups such as CF3(CF2)xCH20CH2-, where x=0,l,2 and 6, has been reported elsewhere.(8) These monomers were polymerized in the presence of a Lewis acid catalyst and an alcohol initiator to give the corresponding hydroxy-terminated polyether prepolymer with fluoroalkyloxy side chains in 90-95% yields. 

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