Polyurethanes elastomeric

The polymerization of tetrahydrofuran was first studied ia the late 1930s (3,4). In 1960, this work was summarized (4), and the Hterature on tetrahydrofuran polymers and polymerization has been growing ever siace. Polytetrahydrofuran with hydroxy end groups has become a large-scale commercial product, used mainly as the flexible polyether segment ia elastomeric polyurethanes and polyesters. It is commercially available under the trade names Terathane (Du Pont), Polymeg (QO Chemicals), and PolyTHF (BASF). Comprehensive review articles and monographs have been pubUshed (2,5-8). 

The following mechanism has been proposed to explain the kinetics of the radiation curing process for elastomeric polyurethanes and polythio ethers. 

Seed stage medium, 77 28 Seed trains, in fermentation, 7 7 42 Segmented-arc nozzle design, 76 8 Segmented elastomeric polyurethane fibers, 25 476-477... 

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. 

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

Segmented elastomeric polyurethane fibers (Spandex fibers) based on MDI have also been developed. 

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... 

Elastomeric polyurethane fibers [96, pp. 609-615], are contained in stretch articles and in knitted fashion materials. Light shades can be dyed tone-on-tone on polyamide-polyurethane mixtures with disperse dyes at 95-98°C and pH 6-7. However, the wetfastness of these dyeings on polyurethanes is lower than on polyamide. Because of the temperature sensitivity of polyurethane fibers, mixtures of elastomeric and polyester fibers must be dyed with small-molecular, rapidly diffusing disperse dyes in 30 min at 120 °C according to the HT process [148], Modified PES fibers that are dyeable at 100°C without a carrier are often used in mixtures with elastomeric fibers. In all dyeing processes for elastomeric fibers, dyeing equipment that permits low-strain guidance of the material and the lowest possible thermal stress are important. 

In our laboratory, much attention has been devoted to the investigation of in situ sequential polyurethane/poly(methyl methacrylate) interpenetrating polymer networks (SEQ PUR/PAc IPNs) (2- ) in which the elastomeric polyurethane network is completely formed in the presence of the methacrylic monomers before the onset of the radical copolymerization which leads to the second network. To each polymerization process corresponds a typical kinetics, which however is not completely independent from each other ( -8). The results obtained with such SEQ IPNs show that the properties do in... 

Figure 4.7 Elastomeric polyurethane waterproofing membrane on a roof terrace. Reproduced with permission from Fosroc...

Thermoplastic elastomers are most commonly formulated from elastomeric polyurethane or block copolymers of polystyrene-elastomer, polyamide-elastomer, or polyether-elastomer bases. Thermoplastic elastomers are provided as a raw material in pelletized form for subsequent compounding. The internal domain structure that is required for thermoplastic-elastomeric performance has been established by specific considerations of blending and structural-chemical interactions. In compounding operations, specific temperature ranges are required to assure that phase separation does not occur in the TPE base polymer. 

MAJOR INGREDIENTS OF RIM ELASTOMERIC POLYURETHANES FOR FASCIA APPLICATIONS... 

Amerthane. (Ameron Protective Coat-iiigs] Elastomeric polyurethane. 

Bayflex. [Bayer Miles] Integral skin or elastomeric polyurethane foam (RIM). 

Stevens. [Stevens Elastomerics] Polyurethane film for headphone ear pads, wheelchair pads, IV xessure infiisers, inflatable splints, artificial heart components, scuba divers buoyancy compensators, diaphragms, cable jacketing, pkg., fabric laminates, adhesive tapes, noise/vibration dampers. 

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