Single-phase polyurethane

Elastic Modulus, Network Structure, and Ultimate Tensile Properties of Single-Phase Polyurethane Elastomers... 

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... 

The single phase polyurethanes were obtained by first reacting a small amount of DAAB with MDI or TDI in DMF solution and subsequent addition of poly(tetramethylene adipate) diol, i. e., no EDA chain extender was used (13). 

Figure 13. Molecular structure of a single-phase polyurethane containing a few chromophoric hard segments.

Also, single-phase polyurethane PUE-TL was synthesized for comparison of sorption properties of this material and nano-heterogeneous SPUU. PUE-TL was synthesized on the base of prepolymer of OTM cured by mixture of the initial OTM and ohgopropyl-ene oxide triolLaprol 373 (M = 370 g mol ). 

Table 6.5.1 contains data values for Q, Cp for three heterogeneous elastomers with urethane urea hard segments and a single-phase polyurethane PUE-TL. It is seen that pre-liminaiy strain e = 350% does not practically affect the equilibrium swelling and the equilibrium concentration of this material at swelling in DEHP and HP-470. 

Table 6.5.2. Network parameters for SPUU and single-phase polyurethane PUE-TL before strain and after strain up to 350%...

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