Polyether diols

Cyclic ether and acetal polymerizations are also important commercially. Polymerization of tetrahydrofuran is used to produce polyether diol, and polyoxymethylene, an excellent engineering plastic, is obtained by the ring-opening polymerization of trioxane with a small amount of cycHc ether or acetal comonomer to prevent depolymerization (see Acetal resins Polyethers, tetrahydrofuran). 

Some of the simplest polyols are produced from reaction of propylene oxide and propylene glycol and glycerol initiators. Polyether diols and polyether triols are produced, respectively (27) (see Glycols). 

Polyester and polyether diols are used with MDI in the manufacture of thermoplastic polyurethane elastomers (TPU). The polyester diols are obtained from adipic acid and diols, such as ethylene glycol, 1,4-butanediol, or 1,6-hexanediol. The preferred molecular weights are 1,000 to 2,000, and low acid numbers are essential to ensure optimal hydrolytic stabihty. Also, caprolactone-derived diols and polycarbonate diols are used. Polyether diols are... 

There is also growing interest in multi-phase systems in which hard phase materials are dispersed in softer polyether diols. Such hard phase materials include polyureas, rigid polyurethanes and urea melamine formaldehyde condensates. Some of these materials yield high-resilience foams with load deflection characteristics claimed to be more satisfactory for cushioning as well as in some cases improving heat resistance and flame retardancy. 

The polyols used are of three types polyether, polyester, and polybutadiene. The polyether diols range from 400 to about 10,000 g/mol. The most common polyethers are based on ethylene oxide, propylene oxide, and tetrahydrofuran or their copolymers. The ether link provides low temperature flexibility and low viscosity. Ethylene oxide is the most hydrophilic and thus can increase the rate of ingress of water and consequently the cure rate. However, it will crystallize slowly above about 600 g/mol. Propylene oxide is hydrophobic due to hindered access to the ether link, but still provides high permeability to small molecules like water. Tetrahydrofuran is between these two in hydrophobicity, but somewhat more expensive. Propylene oxide based diols are the most common. 

Polyester diols are often combined with polyether diols to provide green strength through crystallization or elevated r . Most prevalent and least expensive is hexamethylene diol adipate (HDA) with a Tm of about 60°C. A variety of polyesters are available with various levels of crystallinity — from wax-like to amorphous — and crystallization rate, and with values ranging well below 0°C to above room temperature. Polybutadiene diols are the most expensive and most hydrophobic. They provide low surface tension and thus good wet out of non-polar surfaces. 

Yang and coworkers did the most efforts on the development of network polyester based on citric acid. " They investigated the reaction of citric acid with a series of aliphatic diols (from 3-16 carbon chains) and polyether diols such as polyethylene oxide (PEG), in which 1,8-octanediol (POC) and 1,10 decanediol (PDC) have been studied the most. 

The hot curing process normally uses polyether diol precursors with molecular weights of 3,000 to 5,000 g/mole. We can control the stiffness of the foam by adjusting the average number of isocyanate groups on the chain extender molecules. The higher the functionality of the isocyanate molecules, the more crosslinked, and hence stiffer, will be the product. 

Polyether-foZoc/ -polyesther, 7 646 Polyether diols, 14 271 20 76 25 476 Polyetheretherketone (PEEK) fibers,... 

Pluronics Block polyether diols Wyandotte Corp. 

Polyethers. Three structurally different polyether diols are mainly used poly(1,2-oxypropylene)diol (PPG), poly(1,2-oxybutylene)diol (B-2000), both terminated essentially by secondary hydroxyl groups, and poly (l,4-oxybutylene)diol, a considerably more reactive component owing to primary hydroxyl termination. Of these the poly(oxypropylenes)... 

Elastomeric, lignin-derived polyurethanes can be produced from a three-component system, in which a polyether diol (like PEG) is used as soft segment, provided that the crosslink density is held at a low level and that the soft segment content is high enough to keep T below room temperature. 

Polyether diols form a very important segment of the diols used in the manufacture of polyurethanes. The normal route is by addition polymerization of the appropriate monomeric epoxide. The most important polyethers are polypropylene glycol (C3) and polytetramethylene glycol (C4). The manufacturing route is given in Figure 2.10. 

Compared to polyester-based systems, polyether diols require a greater degree of activation. The solution is to use a combination of a tin and an amine catalyst to obtain the required speed. 

Polyurethane-based FTPEs are produced by reacting fluorinated polyether diols with aromatic disocyanates. The resulting block copolymers contain fluorinated polyether soft segments.68 Another possible method of preparation of fluorinated TPE is dynamic vulcanization. Examples are a blend of a perfluoroplastic and a perfluoroelastomer containing curing sites or a combination of VDF-based fluo-roelastomers and thermoplastics, such as polyamides, polybutylene terephtalate, and polyphenylene sulhde.69 70... 

In addition, telomers which exhibit carboxy end-groups have been esterified with telechelic polyether diols and a,co-difunctional PDMS have been mainly used as the central block, as in the three following examples [132-134] ... 

Polyurethane-based FTPEs are produced by reacting fluorinated polyether diols with aromatic diisocyanates. The resulting block copolymers contain fluorinated... 

This method has been applied to polyether triol-diisocyanate as well as polyether diol-trimethylolpropane-diisocyanate systems 142). The application of the branching theory enables to deal with systems involving groups of unequal and dependent reactivities. Determination of the substitution effect within amino groups in the epoxide-amine reactions is explained in a recent review143>). 

Polyether diols 2,4-toluene diisocyanate 1,2,6-hiexane triol... 

The catalyst makes it possible to product outstandingly high-equivalent-weight polyether polyols, e.g., about 10,000. In other words, polyether diols of 20,000 molecular weight and polyether triols of 30,000 molecular weight can be produced. 

There are various procedures for the preparation of polyethers. These procedures typically start with oxirane or oxirane derivatives (e.g. propylene oxide, etc.). Base catalyzed anionic polymerization, acid initiation, or complex coordination catalysis can be used for the reaction [1-3], Not only oxiranes can generate polyethers. Diols also can be used for polyether synthesis. Other source compounds include tetrahydrofuran, which can be polymerized to a polyether using fluorosulfonic acid (HSO3F) as a catalyst, oxetane (trimethylene oxide) or oxetane derivatives, which can be polymerized to generate polyethers with practical applications such as poly[bis(chloromethyl)oxetane], etc. 

Polyether Diols From Urethane Resin Scrap. Organic and Polymer Waste Reclaiming Encyclopedia, p. 341. 

Polyurethane pre-polymer or thermoplastic polyurethanes are prepared by the reaction of polyester or polyether diols with diisocyanates. The reaction can be conducted in bulk, in a solvent, or in an aqueous solution or dispersion. Unless the reaction is carried out at an elevated temperature a catalyst is required. Organotin compounds are the prime catalyst for this reaction. 

Long-Chain Polyether Diols. Examples of long-chain poly ether diols of molecular weight 102—103 are [85] ... 

The contribution by the polyether diols of similar molecular weight to the flexibility of the PUR end product increases in the order PEG < PPG < PTMEG. The high degree of rotational freedom in PTMEG makes it an ideal polyol for the assembly of elastic PURs such as Spandex and its worldwide demand is estimated to be about 100 million lb. 

The polyether diols derived from polyesters seem to represent a compromise between cost and their contribution to superior elongation and tensile properties as compared to plain polyether diols polyether diols from polyester account for about 10% of the flexible PUR production. Examples of useful products formed from hydroxy-terminated esters of terephthalic acid (TPA)— formed, in turn, by the reaction of an excess of glycols with dimethyl terephthalate (DMT) or TPA—and TDI or MDI-PMDI are flexible ski clothing, gaskets, rollers for printing presses, etc. [85],... 

The materials employed in these formulations consisted of bitolylene diisocyanate (3,3 -dimethyl-4,4 -biphenylene diisocyanate, 136T Upjohn Co.) referred to as T0DI, a polyether diol (tetramethyleneoxide polyol, Polymeg 2000, Quaker Oats Co.), a polyester diol (caprolactone polyol, PCP-200, Union Carbide Corp.) and a chain extender, 1,4-butanedio1 (Aldrich Chemical Co.). The formulations were prepared by a two-step procedure. In... 

The polymerisation reaction of PO, initiated by a bifunctional starter such as 1,2 propyleneglycol, leads to the formation of polyether diols, each hydroxyl group generating a polyetheric chain, terminated by a hydroxyl group [1-13] ... 

The presence of water in starters or in monomers (PO, EO or BO) always leads to polyether diols. The control of water content in the raw materials, used for polyether polyol synthesis, has a great practical importance for two reasons ... 

Figure 4.5 shows some structural possibilities for polyether diols and polyether triols [1-13]. 

The polyether diols are used especially for PU elastomers, coatings adhesives and sealants. 

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