Properties anisotropic

Molecules of nematic Hquid crystals also are aligned in flow fields which results in a viscosity that is lower than that of the isotropic Hquid the rod-shaped molecules easily stream past one another when oriented. Flow may be impeded if an electric or magnetic field is appHed to counter the flow orientation the viscosity then becomes an anisotropic property. 

Whisker and Short Fiber Composites. Whiskers and short fibers tend to align during forming, lea ding to anisotropic properties and large... 

Discuss, giving specific examples, how the anisotropic properties of wood are exploited in the practical applications of this material. 

Boron nitride has two crystalline forms, hexagonal (h-BN) and cubic (c-BN), with much different properties. Hexagonal BN is the more important and has many industrial applications. Its structure is similar to that of graphite which it resembles in many ways. It has a very large anisotropy in the crystal with resulting anisotropic properties. 

Nucleation The formation of sohd crystalhne nuclei on a foreign substrate is basically subject to the same laws as the formation of noncrystalhne nuclei. Specific features found in the case of crystalline nuclei are (1) considerably higher ESE values (2) a faceted rather than spherical shape and (3) anisotropic properties (i.e., different ESE values o, for different crystal faces /) ... 

One-dimensional structures do not exist. Structures are always three-dimensional. The term one-dimensional is acceptable to express specifically named, highly anisotropic properties, such as one-dimensionalconductivity , one-dimensionalconnection or onedimensional disorder . The dimensionality of a structure is a meaningless phrase. 

The parts are often anisotropic. Properties are different in the machine and the transverse directions. 

Note The symmetry of the tensor representing the average anisotropic property cannot be lower than the symmetry of the phase. 

Flory, in 1956, predicted that solutions of rodlike polymers could also exhibit LC behavior. The initial synthetic polymers found to exhibit LC behavior were concentrated solutions of poly(gamma-benzyl glutamate) and poly(gamma-methyl glutamate). These polymers exist in a helical form that can be oriented in one direction into ordered groupings, giving materials with anisotropic properties. 

From a practical point of view, the deviation from main-chain continuity is the most interesting one. Especially the concept of the so-called parallel offset of the main chain is favorized. It is realized in a commercial product made from 4-hydroxybenzoic acid and 2,6-hydroxynaphthalenecarboxylic acid. The incorporation of small amounts of 2,6-hydroxynaphthalenecarboxylic acid causes a discontinuity in the main chain but only in form of a parallel offset of some chain segments. Thus, the ability to form liquid crystalline states is largely maintained as well as the anisotropic properties of the molten and solid polyester. Instead, the melting point is significantly reduced, as desired. 

Spach MS, Dolber PC, Heidlage JF Influence of the passive anisotropic properties on directional differences in propagation following modification of the sodium conductance in human atrial muscle. A model of reentry based on anisotropic discontinuous propagation. Circ Res 1988 62 811-832. Spach MS, Heidlage JF The stochastic nature of cardiac propagation at a microscopic level. Electrical description of myocardial architecture and its application to conduction. Circ Res 1995 76 366-380. Spach MS, Josephson ME Initiating reentry The role of non-uniform anisotropy in small circuits. J Cardiovasc Electrophysiol 1994 5 182-209. 

---