ABSTRACT
During the last two decades a new class of polymeric materials has been developed which received a great deal of attention from both industry and academia. These materials are called liquid crystal polymers (LCPs). In the liquid state, either as a solution (lyotropic) or a melt (thermotropic), they lie between the boundaries of solid crystals and isotropic liquids. This polymeric state is also referred to as a mesomorphic structure, or a mesophase, a combined term adopted from the Greek language (mesos = intermediate; morphe = form). This state does not meet all the criteria of a true solid or a true liquid, but it has characteristics similar to both a solid and a liquid. For instance, the anisotropic optical properties of LC polymeric fluids are like those of crystalline solids, but their molecules are free to move as in liquids. The main difference between these polymers and the conventional liquid crystals used in electrical display devices is the molecular weight. LCPs have a much higher molecular weight. This difference provides unique features. Especially important is the existence of a glass transition point which permits freezing of an LC phase for use over a wide range of temperatures.
