Flow columnar phases

Hence, columnar (discotic) liquid crystals with an aromatic central core are of significant interest for application in OLEDs as an HTL, if the columnar phase can be aligned with the columns orthogonal to the substrate surface, i.e. the flow of holes from the anode to the ETL and/or emission layer is... 

An important aspect of the macroscopic structure of liquid crystals is their mechanical stability, which is described in terms of elastic properties. In the absence of flow, ordinary liquids cannot support a shear stress, while solids will support compressional, shear and torsional stresses. As might be expected the elastic properties of liquid crystals are intermediate between those of liquids and solids, and depend on the symmetry and phase type. Thus smectic phases with translational order in one direction will have elastic properties similar to those of a solid along that direction, and as the translational order of mesophases increases, so their mechanical properties become more solid-like. The development of the so-called continuum theory for nematic liquid crystals is recorded in a number of publications by Oseen [ 1 ], Frank [2], de Gennes and Frost [3] and Vertogen and de Jeu [4] extensions of the theory to smectic [5] and columnar phases [6] have also been developed. In this section it is intended to give an introduction to elasticity that we hope will make more detailed accounts accessible the importance of elastic properties in determining the... 

Characteristic flow geometries for hexagonal columnar phases. 

Utracki and Lyngaae-Jprgensen [2002] observed several common aspects of exfoliated CPNCs and liquid-crystal polymers (LCPs). Similar six-phase structures are predicted for CPNCs and observed in LCPs isotropic, nematic, smectic-A, columnar, house of cards, and crystal [Porter and Johnson, 1967 Balazs et al., 1999 Ginzburg et al., 2000]. These phases in CPNCs originate in a balance between the thermodynamic interactions, clay concentration, and platelets orientation, while in LCPs they depend mainly on temperature. Since it is more difficult on the one hand to prepare disk-shaped than rigid-rod molecules, and on the other to develop flow theory for LCPs with disk moieties, the number of publications on the latter systems is small [Ciferri, 1991]. 

Tubular and columnar apparatus (apparatus length-to-diameter ratio L/d > 100) including screw equipment relate to plug-flow reactors type [7,8]. Plug-flow reactors are applied for many of gas-phase reactions realized in production quantities, in particular for ethylene polymerization under high pressure conditions [9], and for some liquid-phase reactions, for example polystyrene synthesis in columns and other rubbers and plastics productions. Near 10% of polymer and 30% of fibers manufacture are produced in apparatus of such types [10]. 

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