Values for polyurethanes

As a result of increase in molecular weight of prepolymer from 1400 (SPU-1) to 2100 (SPU-4) or partial replacement of MOCA by polypropylene oxide diol (SPU-2) the amount of hard segments and common density of network decreased. But the equilibrium swelling in plasticizers increases (Table 10.15). The SPU modulus of elasticity decreases. The increase in the number of oxygen atoms in a polyether chain (SPU-4) results in decreased swelling in less polar plasticizers (TO, DOS, DOP). The elasticity modulus of the material in these plasticizers varies slightly. A large value for polyurethane SPU-5... 

Table 8 gives values of the real part of the extensional modulus (eqs. 3 and 5) and the loss factor. The values for most of the polymers are outside the glass-transition region, while the values for polyurethanes are typical of the glass-transition region. The high values of tan S are of interest for soimd absorption and for vibration damping. 

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See also in sourсe #XX -- [ , ]

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