Effect of physical treatments on the structural organization of a thermotropic polyester

A main chain liquid crystalline polyester, indicated as LC. 10, was quenched into an unoriented nematic state, and crystallized either thermally or with solvents. The different samples were analyzed by X-rays, differential scanning calorimetry, scanning electron microscopy, and transport properties of dichloromethane vapours at different activities. All the results show that both thermal and solvent treatments induce crystallization, but they transform the nematic phase in profoundly different ways. Thermal crystallization transforms the nematic phase into a crystalline phase, leaving unchanged the uncrystallized part. By contrast, the process of solvent-induced crystallization transforms a part of the nematic phase into the crystalline phase, leaving the remaining part in a more disordered phase, resembling the amorphous phase. These different organizations result in very different transport properties of the materials.