Polyester hydroxyl-terminated

Preparation of Carboxylated Polyesters. Hydroxyl-terminated polyester segments were prepared by conventional procedures and extended with an equimolar amount of dianhydride (2). To avoid the possibility of crosslintdng the polymer, reaction1 with the dianhydride was carried out at 175 °C. Depending upon the size of the reaction mixture, about 1 to 3 hours were required for all of the dianhydride to react and for a medium-to-high melt viscosity to be obtained. Inherent viscosities were 0.3 to 0.4. 

Polyurethanes. The main raw materials for urethanes are organic diisocyanates and various active hydrogen components, such as polyether polyols, hydroxyl-terminated polyesters, hydroxyl-terminated urethane polyethers, vegetable oils modified by alcohol or some diamines. 

Uses. The largest uses of butanediol are internal consumption in manufacture of tetrahydrofuran and butyrolactone (145). The largest merchant uses are for poly(butylene terephthalate) resins (see Polyesters,thermoplastic) and in polyurethanes, both as a chain extender and as an ingredient in a hydroxyl-terminated polyester used as a macroglycol. Butanediol is also used as a solvent, as a monomer for vadous condensation polymers, and as an intermediate in the manufacture of other chemicals. 

TPU is usually made from hydroxyl-terminated polyether or polyester diols, diisocyanates, and bifunctional chain extenders. Since the composition, the synthetic method, molecular weight, and its distribution are all changeable, there are numerous types of TPUs available, and their prices and properties vary significantly. 

The isocyanate group is more reactive than the epoxy group in that it will react at room temperature with water and hydroxyl groups as well as with amine groups. However, the latter reaction is too fast to be practicable so the standard two-pack coatings are based on isocyanate and polyhydroxyl prepolymers such as hydroxyl terminated polyesters or polyethers as in the last example given in the section on epoxy resins. 

Block copolymers with materials such as a polyester (PE) (qv) can be prepd by the reaction of diisocyanate-terminated polyesters with hydroxyl-terminated PMMA according to Wilkes and Grezlak (Ref 21). The basic structure was found to be PMMA-PE-FMMA, with a mw of from 7500 to 47000. The purpose of the work was to produce a stronger copolymer (in terms of stress-strain) by tailoring the amt of each monomer used to produce the copolymer Further information on polymerization can be found in Refs 2a 6a... 

The diisocyanates and polyols are reacted to form a high molecular weight hydroxyl terminated millable gum. These millable gums are compounded and processed as conventional elastomers, both sulphur and peroxides being used to cure the polymers. Here again, polyether and polyester types are available, and the differences between these two types referred to above also apply here. 

A related product is formed from the analogous reaction using hydroxyl-terminated PEO with aromatic diacids to form a segmented aromatic polyester block copolymer that is sold under the trade name Hytrel. 

A polyurethane is fonned by reacting a hydroxyl-terminated polyether or polyester with an isocyanate. An example in commercial practice is the reaction of toluene diisocyanate and polypropylene glycol (PPG) to produce one of the most common forms of polyurethane (see Figure 2.6). 

Examples of Separating Hydroxyl-Terminated Polyesters and Polybutadienes... 

Carboxylated polyesters were prepared by extending hydroxyl-terminated polyester segments with dianhydrides. Carboxylated polyesters which were soluble in common lacquer solvents were effective in improving the adhesion of coatings on a variety of substrates when 1-10% was blended with cellulose acetate butyrate, poly(vinyl chloride), poly(methyl methacrylate), polystyrene, bisphenol polycarbonates, and other soluble polymers. 

The carboxylated polyesters were prepared by a two-step process (1) preparation of a hydroxyl-terminated polyester segment and (2) reaction with a dianhydride to extend the polyester and introduce carboxyl groups. When the dianhydride is pyromellitic (II), the equation is as follows ... 

The unstable prepolymers are typified by the Bayer Vulkalon polyurethane. Vulkalon is generally made by reacting naphthalene diisocyanate (NDI) and hydroxyl terminated polyesters to form a prepolymer. The reactivity of the... 

Polyurethanes (PU) are a special class of polymers containing the urethane group, (—NH-CO-O-), commonly prepared by a condensation reaction between a diisocyanate and a diol, such as hydroxyl terminated polyether or polyester ... 

Massa, Voit, and coworkers1231 conducted a survey of the phase behavior of blends of these polyester hyperbranched polymers with linear polymers. Blend miscibility of a hydroxyl terminated polyester was comparable to that of poly(vinylphenol) indicating strong H-bonding interactions, whereas miscibility of an acetoxy terminated analog decreased relative to the hydroxy derivative. 

Hydroxyl-terminated polyesters and polyols without ester linkages... 

This reaction is often employed in the production of flexible urethane foams, which are frequently block copolymers of polyether or polyester segments joined to polyurea segments. (The polyester or polyether segments terminate in urethane segments resulting from reaction of polyether or polyester hydroxyl end groups with the isocyanate.)... 

Polyols. The polyols for urethane foams are oligomers or polymeric compounds having at least two hydroxyl groups. Such polyols include polyether polyols, polyester polyols, hydroxyl-terminated polyolefins and hydroxyl-containing vegetable oils. 

Unsaturated polyesters with terminal hydroxyl or carboxyl groups can also react at the same time with isocyanate groups and a vinyl monomer, such as styrene, to produce hybrid polymers. Two kinds of reactions, the NCO-OH addition reaction and radical polymerization by the vinyl groups, can occur. In parallel to the two reactions, interference between the two reactions also can occur. Detailed studies on the interference reactions were studied by Hsu et al. (190). 

Hydroxyl-Containing Unsaturated Compounds/Polyurethane Hybrid Foams. Unsaturated polyesters have terminal hydroxyl groups and unsaturated linkages in the polymer skeleton (34). Vinyl esters have terminal vinyl groups and pendant hydroxyl groups. These model structures are shown in Equations (1) and (2) respectively. 

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