Basic Requirements for Liquid Crystal Formation

These last three chapters delineate the three bulk forms of polymers amorphous, crystaUine, and liquid crystalline. How are they best distinguished in the laboratory Key experiments involve X-ray diffraction, optical microscopy, and methods of observing transitions. Typical results are as follows  

1- or 2-D order Schlieren texture Tg and two or more first-order transitions 

A Uquid crystal must satisfy three basic requirements, regardless of molecular size or shape  

There must be a first-order transition between the true crystalline state at the lower temperature bound leading to the liquid crystaUine state, and another first-order transition leading to the isotropic liquid state (or 

A liquid crystal must exhibit one- or two-dimensional order only true crystals have three-dimensional order, and the isotropic liquid is completely disordered. 

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