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Cycling tensile response with varying the hard segment content

2 Cycling tensile response with varying the hard segment content [Pg.128]

As shown by Abouzahr and Wilkes [176] in the case of MDI based PUs extended with EDO, morphological changes take place as the HS fraction is increased. The texture changes from that in which little such domain content exists at low HS levels (15%), to that in which the polymer has an interlocking domain morphology at high HS content (35 and 45%). Preferable elastomeric properties (low hysteresis, high extension) can be obtained when isolated HS domains exist (25% HS). [Pg.128]

Materials that possess rather distinct domain textures show the lowest hysteresis characteristics while those with no domain texture show an increasing level of hysteresis with strain. This was explained by Abouzahr [176] in terms of a [Pg.128]

As shown by Abouzahr, the kinetics of domain formation was found to be dependent on the driving force for segment segregation and the viscoelastic properties of the material. [Pg.129]

Russo and Thomas studied a series of PUs with increasing percent of hard segment by mechanical testing at low strain rate [300]. They found that an increase in the HS content results in an increase in the initial modulus, and of ultimate strength, and also determines a decrease of the elongation to break. [Pg.129]




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