Liquid crystalline polymers LCPs solid state structures

Liquid crystalline polymers (LCPs) are best thought of as being a separate, unique class of TPs. Their molecules are stiff, rodlike structures organized in large parallel arrays or domains in both the melted and solid states. These large, ordered domains provide LCPs with characteristics that are unique compared to those of the basic crystalline or amorphous plastics (see Table 2-9) [2]. 

For example, if the time for the process to occur is faster than the longest relaxation time, then the fluid behaves more like an elastic solid. For the liquid crystalline systems there seems to be two relaxation times which are important. One is the time for relaxation of orientation and the other is the time for relaxation of stress. Whereas these phenomena are connected for flexible chain polymers, they seem to separate for liquid crystalline polymers. In other words, there are several stress free states for LCP. Some of the behavior observed may be partly due to the copolymer nature of thermotropic systems. However, the lyotropic systems based on the polyamide structure also exhibit similar behavior. 

Liquid crystal polymers (LCPs) were introduced over the last three decades. 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. 

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