Thermal and Rheological Properties of a Liquid-Crystalline Polyurethane

摘要

In recent years considerable interest has developed in the rheological properties of thermotropic liquid-crystalline polymers. This is a consequence of their potential application as high-strength fibers and plastics and their unusual properties in the melt due to structural order in the fluid phase. Some of the main rheological phenomena present in these melts include unusually long relaxation times, apparent yield stresses, minima in viscosity as a function of temperature, considerably lower viscosities than comparable amorphous polymers, and negative values of the first normal stress difference. Reprints. (jes)