The Mesomorphic State, Liquid Crystal Polymers

For all homopolymers the rate of crystal growth increases linearly with time, or G = dr/dt. Mandelkem defines the steady-state nucleation rate, N as follows [42]  

If the crystallization takes place over an extended temperature range, most if not all homopolymers display a maxima in rates of spherulitic growth and in the overall crystallization. The equation for spherulitic growth is written as follows [42]  

The state of mesomorphism is a spontaneously ordered liquid-fluid crystalline state. Liquid crystals were discovered as early as 1888. They are materials that exhibit order in one or two dimensions but not in all three. By comparison, the amorphous materials lack any order, while the crystalline ones exhibit order in three dimensions. All liquid crystalline polymers exhibit some degree of fluidity. They were investigated extensively in the 1900s and became commercially important in 1960s. 

These are macromolecules that can align into crystalline arrays while they are in solution lyotropic) or while in a molten state thermotropic). Such liquids exhibit anisotropic behavior [51,52]. The regions of orderliness in such liquids are called mesophases. Molecular rigidity found in rigid rod-shaped polymers, for instance, is the chief cause of their liquid crystalline behavior. It excludes more than one molecule occupying a specific volume and it is not a result of intermolecular attractive forces. Some aromatic polyesters or polyamides are good examples, like polyphenylene terephthalate  

Because the molecules posses anisotropy, they are aligned while still in a fluid form. This differs from ordinary liquids, that are isotropic, where the molecules lack any kind of arrangement. 

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