Discotic liquid crystals phase transition temperatures

For example, the 815 cm-l peak shifted to 825 cm i and the doublet at 1730/1750 cm-l, indicative of crystal-like structures has disappeared at the highest shear rate. The spectral changes near 815 cm-1 of Fig. 15a could conceivably correspond to those of Fig. 13 which contained the spectra at different temperatures around the discotic/ isotropic liquid transition. On the other hand, no disappearance of the carbonyl structures occurred with simple phase transition. TTie disappearance of the carbonyl bands at 1730/1750 cm at the highest shear rate must therefore corresponds to a molecular realignment in which the dipole moment changes causing the infixed bands have been reoriented along the direction of observation. 

The second group comprises thermotropic polymers. The phase transitions of thermotropic liquid crystals are achieved when a determined temperature range is reached. The fundamental unit that induces structural order in this kind of polymer presents with high rigidity and anisotropic shape [26,27]. Two major subclasses can be distinguished according to this shape discotic (disc-Uke molecules) and... 

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