Elastomers from polyether diols

The PU elastomers obtained from polyether diols with DMC catalysts (Acclaim Polyols of Bayer) have a spectacular improvement in the majority of physico-mechanical properties when compared with PU elastomers made from the polyether diols, obtained by anionic catalysis. 

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... 

The polyether diols, THF-alkylene oxide copolymers are used especially for preparing PU elastomers with high elastic properties (elongation, modulus, tear and tensile strength), superior to those of PU elastomers derived from polyalkylene oxide polyether diols (PO homopolymers or PO-EO copolymers). 

The principal of formation of this type of polyurethane elastomer medium, based on a cationic urethane latex, is where an isocyanate-terminated prepolymer derived from either a polyester or polyether diol and toluene diisocyanate is first chain-extended with an alkyl diethanolamine to yield a relatively low molecular weight urethane capable of further chain-extending reactions. Emulsification occurs when the partially extended urethane is added with high-speed mixing to 3% aqueous acetic acid. Curing of the latex takes place either by reaction of water with the terminal isocyanate groups or by reaction with water-soluble diamines. 

In addition, polyester polyols are made by the reaction of caprolactone with diols. Poly(caprolactone diols) are used in the manufacture of thermoplastic polyurethane elastomers with improved hydrolytic stabiHty (22). The hydrolytic stabiHty of the poly(caprolactone diol)-derived TPUs is comparable to TPUs based on the more expensive long-chain diol adipates (23). Polyether/polyester polyol hybrids are synthesized from low molecular weight polyester diols, which are extended with propylene oxide. 

Studies have been made of the elastic (time-independent) properties of single-phase polyurethane elastomers, including those prepared from a diisocyanate, a triol, and a diol, such as dihydroxy-terminated poly (propylene oxide) (1,2), and also from dihydroxy-terminated polymers and a triisocyanate (3,4,5). In this paper, equilibrium stress-strain data for three polyurethane elastomers, carefully prepared and studied some years ago (6), are presented along with their shear moduli. For two of these elastomers, primarily, consideration is given to the contributions to the modulus of elastically active chains and topological interactions between such chains. Toward this end, the concentration of active chains, vc, is calculated from the sol fraction and the initial formulation which consisted of a diisocyanate, a triol, a dihydroxy-terminated polyether, and a small amount of monohydroxy polyether. As all active junctions are trifunctional, their concentration always... 

Physical properties are related to ester-segment structure and concentration in thermoplastic polyether-ester elastomers prepared hy melt transesterification of poly(tetra-methylene ether) glycol with various diols and aromatic diesters. Diols used were 1,4-benzenedimethanol, 1,4-cyclo-hexanedimethanol, and the linear, aliphatic a,m-diols from ethylene glycol to 1,10-decane-diol. Esters used were terephthalate, isophthalate, 4,4 -biphenyldicarboxylate, 2,6-naphthalenedicarboxylate, and m-terphenyl-4,4"-dicarboxyl-ate. Ester-segment structure was found to affect many copolymer properties including ease of synthesis, molecular weight obtained, crystallization rate, elastic recovery, and tensile and tear strengths. 

The largest-volume polyether used is obtained from propylene oxide polymerized under basic conditions. Polyester polyols are produced from a number of different materials involving diacids and diols to give the ester linkage. Aliphatic polyesters generally are used for elastomers to impart chain flexibility. 

AO containing various phenolic moieties were prepared by transesterification in the presence of tetraalkyl titanates. Randomly distributed -active moieties are characteristic of 140 (only the hard polyester segment is given) prepared from dimethyl terephthalate, 1,4-butanediol, poly(tetramethylene oxide)diol and dimethyl 5-(3,5-di-tm-butyl-4-hydroxybenzenepropaneamido)isophthalate [181]. The mentioned polymeric AO was used for stabilization of polyether-polyester elastomers. A partial attachement of tetrakis[methylene 3(3,5-di-tert-butyl-4-hydroxy-phenyl)propionate]methane (3) via transesterification reaction was expected in the synthesis of another polyether-polyester elastomer by [182]. A reversible redox polyester was formed from 2,5-bis(2-hydroxyethyl)hydroquinone and dichlorides of aliphatic dicarboxylic acids [137],... 

Polyurethane elastomers derive their elastomeric properties from phase separation of the hard and soft copolymer segments, such that the hard (urethane) segment domains serve as crosslinks between the amorphous soft segment domains, which are usually polyesters or polyethers. We are interested in the systems in which the hard segments are prepared from diphenyl-methane 4,4 -diisocyanate (MDI) with a linear diol as the chain extender ... 

Thus, from high MW diols (MW = 1000-4000 daltons) polyethers (polyalkyleneoxides, polytetrahydrofuran (PTHF)), polyesters, polycarbonates (PC), polybutadienes, etc., by the reaction with diisocyanates [toluene diisocyanate (TDI), or pure diphenyl methane diisocyanate (MDI)], high MW linear polyurethanes are obtained (no crosslinking), with high elasticity (polyurethane elastomers, spandex fibres, some adhesives and sealants, etc). 

The index m in Eqs. [10.33] and [10.34] is a measure of ability of a liquid to mpture a physical network of elastomer. Table 10.13 presents the values of the m parameter obtained at 298K for swelling of PBU crosslinked polydiene urethane epoxide, PDUE, crosslinked elastomers of butadiene-nitiile mbbers SCN-40, SCN-26, SCN-18 and also for crosslinked polyether urethane, PEU, synthesized from polytetramethylene oxide diol having M. 1000. Dibutyl phthalate, DBP, and tributyl phosphate, TBP, were used. 

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