Rheological properties of lyotropic liquid crystals

✍ Scribed by Maria Regina Alcantara; JoséAtilio Vanin

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 373 KB
• Volume: 97
• Category: Article
• ISSN: 0927-7757
• DOI: 10.1016/0927-7757(94)03078-e

✦ Synopsis

Rheological studies of liquid crystalline systems based on sodium decylsulphate are reported. It was verified that for low shear rates, disk-like (ND) micellar nematic mesophases show typical pseudo-plastic rheopectic behaviour, associated with a favourable orientation of anisometric micelles in the flow field. The existence of a recovery time was observed, probably due to an orientational competition between flow effects and intermicellar interactions. The same sample observed at higher shear rates exhibited Newtonian behaviour, acting as a "dilute" system in which the interactions between the components are not sufficiently strong to prevent free diffusion.

For rod-like (Nc) micellar nematic mesophases at low shear rates, rheopectic behaviour was observed. Additionally, a typical structural viscosity was detected, attributable to a superstructure break down arising from the shearing flow. For Nc systems, the existence of a recovery time was observed only for low shear rate values, indicating that for higher values the flow completely orients the sample.