Polyurethane ionomers, applications

Polyurethane ionomers, 25 460 Polyurethane-modified isocyanurate (PUIR) foams, 25 455, 456 Polyurethanes (PUs), 9 564. See also Polyurethane (PU) antioxidant applications, 3 121-122 cardiovascular device applications, 3 720 CASE, 25 474-477 commercial block copolymers, 7 648t containing sulfur linkages, 23 742-745 dyeing, 9 204... 

Interest in polyurethane ionomers has increased in the last decade because of their growing uses in water-based coating, adhesives, medical, and semiconductor applications. However, relatively little information has been published regarding the synthesis and... 

The thickening of SMC can be accelerated using hydroxy-terminated im-saturated polyesters in conjimction with isocyanate-terminated prepolymers. Polyurethane ionomer-based sizings for glass fibers used in RRIM applications are also known. 

The sensitivity to hydrolysis is a key issue in many applications. The ester bond in 4GT-PTMO copolymers is sensitive to hydrolysis however, it is fairly protected since most of the ester is contained in a crystalline structure. The addition of a small amount (1-2%) of a hindered aromatic polycarbodiimide substantially increases the lifetime of this material in the presence of hot water or steam (Brown et al., 1974). Polyurethanes are susceptible to hydrolytic attack, especially those with polyester soft segments. However, polyester soft segment polyurethanes are generally more resistant to oils, organic solvents, and thermal degradation. lonomers will swell when exposed to water in fact, a commercial hydrated perfluorosulfonic ionomer (Nation) is used as a membrane separator in chlor-alkali cells. Styrene-diene copolymers and polyolefin TPEs are insensitive to water. 

Solutions (5-25% solids) of fully reacted polyurethanes based on MDI or IPDI are also used in coating applications. These coatings are used mostly as finish coats on fiexible substrates. Because of concern over airborne solvents aqueous polyurethane dispersions are used today. These polymers are prepared by incorporating ionic groups into their backbone, and both cationic and anionic groups are utilized in the preparation of the ionomers. The solvent and water resistance of films formed from aqueous dispersions can be improved by cross-linking. Ionomers are also used in the formulation of speciality adhesives. 

Krdl P. Synthesis methods, chemical structures and phase structures of linear polyurethanes. Properties and applications of linear polyurethanes in polyurethane elastomers, copolymers and ionomers. Prog Mater Sci 2007 52(6) 915-1015. 

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