Diisocyanate Elastomeric

Elastomeric Fiber. Elastomeric fibers are prepared by the polymerization of polymeric polyols with diisocyanates. 

Cycloahphatic diamines react with dicarboxyUc acids or their chlorides, dianhydrides, diisocyanates and di- (or poly-)epoxides as comonomers to form high molecular weight polyamides, polyimides, polyureas, and epoxies. Polymer property dependence on diamine stmcture is greater in the linear amorphous thermoplastic polyamides and elastomeric polyureas than in the highly crosslinked thermo set epoxies (2—4). 

The segments derived from the condensation reaction of the butanediol and the diisocyanate agglomerate into separate phases, which are hard and crystalline. The elastomeric chains are thus cross-linked to form a network similar in many ways to that given by the simple... 

Initiation of stannous octoate-catalyzed copolymerization of e-caprolactone with glycerol was used to prepare a series of trifunctional hydroxy-end blocked oligomers, which were then treated with hexane-1,6-diisocyanate to form elastomeric polyesterurethanes with different crosslink densities (49). Initiation of e-caprolactone polymerization with a hydroxypropyl-terminated polydimethylsiloxane in the presence of dibutyl tin dilaurate has been used to prepare a polyester-siloxane block copolymer (Fig. 4) (50). 

The most important reactions for the production of elastomers, however, utilise diisocyanates and polyols, and the elastomeric products formed can be of the following types. 

Another approach was attempted by Seppala and Kylma who reported the synthesis of poly(ester-urethane)s by condensation of hydroxyl terminated tel-echelic poly(CL-co-LA) oligomers with 1,6-hexamethylene diisocyanate (Scheme 33) [94]. The diisocyanate acts as chain extender producing an increase in molecular weight of the preformed oligomers. The authors claim that some of the copolymers present elastomeric properties. Using a similar method. Storey described the synthesis of polyurethane networks based on D,L-LA, GA, eCL,... 

PUs derived from the reaction of diisocyanates and a variety of hydroxyl-containing materials form the basis for foamed products and a variety of elastomeric materials. 

According to O. Bayer, the latter procedure, which is used especially for the preparation of elastomeric polyurethanes, is carried out in two separate stages. First, a carefully dried, relatively low-molecular-weight, aliphatic polyester or polyether with hydroxy end groups is reacted with an excess of diisocyanate. A chain extension reaction occurs in which two to three linear diol molecules are coupled with diisocyanate, so as to yield a linear polymer with some in-chain urethane groups and with isocyanate end groups. 

Polyurethanes 96 containing 1 have been prepared by several research groups, and complex polyurethanes with an elastomeric character and good mechanical properties were described in a few patents. These polymers were obtained from 1 and diisocyanates in the presence of suitable catalysts, e.g., Braun and Bergmann used triethylamine in dimethylsulfoxide [104]. 

Elastomeric Polyurethanes from a Kraft Lignin—Polyethylene Glycol—Toluene Diisocyanate... 

The two elastomeric polyurethanes listed in Table 1.3, are synthesized in the following way PU-I is the reaction product of a prepolymer based on poly(tetramethylene glycol) ether and 2,4-toluylene diisocyanate (this product is analogous to Adiprenyl-167", Du Pont, USA) PU-II is the... 

Since 1980, siloxane-urea block copolymers prepared by the reaction of bisaminoalkyl-terminated silicones and diisocyanates [1] have been well known in the literature. Silicone is responsible for the elastomeric behavior and urea for the thermal behavior. Nevertheless, to obtain high-molecular-weights in the polymerization of such copolymers, the starting compounds have to be sufficiently pure [2]. Therefore, one key step in the synthesis of such block copolymers is the preparation of... 

Mixtures of isocyanates are commonly used for convenience in commercial production of the diisocyanate, since the pure toluene 2,4-diisocyanate is more expensive to produce. The resulting prepolymer is then mixed with either a glycol, such as 1,6-hexanediol, or a deactivated (sterically hindered) diamine plus pigment if required, and then promptly poured into a preheated mold of the desired shape. In about half an hour the mixture sets to a pliable shape with stiffness and elasticity controlled by the components and processing details used [29]. Similar procedures produce high-strength polyurethane fiber (e.g., Perlon U) or elastomeric fibers (e.g., Spandex and Lycra). 

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