The cholesterization process on lyotropic liquid crystals studied by rheology

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 136; no. 1; pp. 155 - 158
• Main Authors: Alcantara, Maria Regina, Dias, Luís Carlos Fonseca
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30-04-1998
• Subjects: Cholesteric liquid crystals; Liquid crystals; Lyotropic liquid crystals; Rheology; Viscosity; Viscosity; Cholesteric liquid crystals; Lyotropic liquid crystals; Rheology; Liquid crystals
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/S0927-7757(97)00319-1

Rheological studies on cholesteric and nematic liquid-crystalline systems based on sodium dodecylsulphate are reported. Both systems present a plastic behavior with 10 D cm
−2 of yield stress. A decrease in shear stress between successive rheograms was also verified. It was observed that the flow orientation process leads to the alignment of micelles in the flow direction. The cholesteric structure is characterized by a hindrance to an approximation of consecutive planes, which leads to a resistance to the decrease in shear stress in consecutive cycles. It is observed that the consistency index
k increases the cholesterol concentration, showing a strengthening of the helicoidal superstructure as a whole. At the same time, a decrease in the flow index
n was also observed, evidencing an enhancement of the plastic behavior of the system. The results obtained show that the helix becomes more resistant to deformations of its form, revealing a more rigid helicoidal array due to the increase in chiral interaction forces.