Viscoelastic Properties of Polyurethane Block Polymers

Abstract

Abstract Orientation measurements using differential infrared dichroism experiments have been applied to the study of the viscoelastic properties of polyurethane block polymers. The time dependence of the orientation function reflects the influence of both the viscoelastic nature of the blocks and of the two-phase microstructure. A study of the effect of hard block length on the orientation response suggests the presence of an interlocked hard phase structure for most compositions. Such a structure severely restricts relaxation of orientation under strain. At very short hard segment lengths, this morphology is not present and extensive relaxation does occur.