Order and Flow of Liquid Crystals: The Nematic Mesophase

Liquid crystals offer a unique opportunity for physical studies. The nematic mesophase is an aggregate, yet fluid state, which consists of anisometric, rodlike structures. The flow of three nematic‐forming compounds, p‐azoxyanisole, anisaldazine, and p‐anisal‐p‐aminoazobenzene, was studied in both their isotropic and anisotropic states. Studies were made with capillary viscometers and with a high‐shear concentric cylinder viscometer. New density, coefficient of expansion, and transition temperature data are also given. The instrumentation used is described. The results add definition to the viscosity and density anomalies at nematic‐isotropic transitions. The data for p‐anisal‐p‐aminoazobenzene are entirely new. Values for anisaldazine establish previous viscosity and density results on an absolute basis. New results on p‐azoxyanisole contribute a temperature and shear rate extension to previous studies.

[1]  R. Porter,et al.  ORIENTATION OF NEMATIC MESOPHASES , 1962 .

[2]  M. Gibbs,et al.  The Site of Inhibition of Iodoacetamide in Photosynthesis studied with Chloroplasts and Cell Free Preparations of Spinach , 1960, Zeitschrift fur Naturforschung. Teil B, Chemie, Biochemie, Biophysik, Biologie und verwandte Gebiete.

[3]  G. H. Brown,et al.  The Mesomorphic State - Liquid Crystals , 1957 .

[4]  W. A. Hoyer,et al.  Behavior of Liquid‐Crystal Compounds Near the Isotropic‐Anisotropic Transition , 1956 .

[5]  J. R. Muenger,et al.  High Rate of Shear Rotational Viscometer , 1955 .

[6]  R. LeTourneau,et al.  All-Purpose Capillary Viscometer , 1952 .

[7]  M. Miȩsowicz.  The Three Coefficients of Viscosity of Anisotropic Liquids , 1946, Nature.

[8]  E. Stewart.  Dispersion of the Velocity and Anomalous Absorption of Sound in Hydrogen , 1946 .

[9]  W. Ostwald,et al.  Über Viskositätsanomalien sich entmischender Systeme, II. Über die Strukturviskosität mesomorpher Schmelzen , 1933 .

[10]  F. Jaeger.  Über die Temperaturabhängigkeit der molekularen freien Oberflächenenergie von Flüssigkeiten im Temperaturbereich von − 80 bis + 1650° C , 1917 .

[11]  R. Porter,et al.  Viscosity performance of lubricating base oils at shears developed in machine elements , 1961 .

[12]  S. Peter,et al.  Über die Strukturviskosität des kristallin-flüssigenp-p′-Azoxyanisols. , 1955 .

[13]  W. Kast,et al.  Messungen der Viskosität kristalliner Flüssigkeiten nach der Helmholtzschen Methode , 1942 .

[14]  W. Ostwald.  Anomalous viscosity in mesomorphic melts , 1933 .

[15]  R. Schenck.  Untersuchungen über die krystallinischen Flüssigkeiten , 1898 .