Anisotropic polymeric liquid

You can indeed make a super-strong fiber, even stronger than steel, from a polymer, but the polymer must be converted into a special liquid-crystalline state which is really a variety of the viscous state. If you think of a viscous polymer as of some polymeric liquid , then a liquid-crystalline polymer can be regarded as an anisotropic polymeric liquid . The anisotropy occurs spontaneously, with no help from outside (such as orientating fields, mechanical stresses or whatever). 

Liquid crystalline phases are known to couple collectively - and therefore strongly - to external electromagnetic fields, which may be used to induce local variations. If such polymeric liquid crystal phases are rapidly frozen-in, this leads to strongly anisotropic glasses. 

In the previous sections, we discussed constitutive approximations for the stress and surface heat flux in a stationary fluid, where u = 0. In view of the molecular origins of q, there is no reason to expect that the basic linear form for its constitutive behavior should be modified by the presence of mean motion, at least for materials that are not too complicated in structure. Of course, this situation may be changed for materials such as polymeric liquids or suspensions, because in these cases the presence of motion may cause the structure to become anisotropic or changed in other ways that will affect the heat transfer process. We will return to this question in Section J. 

Orthoscopic examination with crossed polars is carried out first of all to determine the isotropism or the anisotropism of a sample. The polarization colors, the defects and variation in molecular orientation, and the orientation pattern or texture of liquid crystals are observed in this examination. With a heating stage the temperature of phase transition is also determined. In addition, with use of a compensator, the determination of vibration directions of the ordinary and extraordinary rays, the determination of relative retardation and birefringence are possible. In this section, the optical basics for orthoscopic observations are briefly outlined. The description of textures frequently observed for polymeric liquid crystals is given in Section 4.1.4. 

In some temperature range the molecules tend to line up parallel to each other, but not in crystal register. This leads to the formation of anisotropic regions, which gives them optical properties that are useful for displays etc. Polymeric liquid-crystal materials have groups similar to these incorporated in the chains. There are two principal types. 

The papers presented in this symposium give some indication of the wide variety of polymers which are now known to form liquid crystalline phases Polymeric liquid crystals are usually classified according to the mesophase structure e g., nematic, cholesteric, smectic A, etc ). However, these classes are quite broad For example, the cholesteric lyotropic phases formed by synthetic polypeptides in suitable solvents differ markedly from the cholesteric thermotropic phases formed from silicone polymers with cho-lesteryl ester side chains. In particular, the driving forces behind the formation of the mesophases are quite different for these two examples, being essentially due to chain stiffness in the first case and to anisotropic dispersion force interactions in the second case It may therefore be useful to classify polymeric liquid crystals according to the polymer chain structure ... 

Most crystalline solids are anisotropic. Since our main conc is polymeric liquids and rubbery solids, we generally do not need to worry about anisotropy. The general roach to constitutive equations for anisotnqnc materials is to use a different elastic constant for each direction. In general, to relate stress to deformation requires a fourth rank tensor with 3 components... 

In these cases, the anisotropic phase is usually not only formed in the pure polymer (in a polym melt) but also in a comparatively concentrated solution of such macromolecules. Liquid-crystal polymer melts are firequently called thoTOotropic polymeric liquid crystals (since the liquid-crystalline transition can most naturally be caused by a change in the temperature for these substances), and anisotropic polymer solutions are called lyotropic liquid crystals. 

The image-producing device comprises a liquid crystal cell with a liquid crystal between two plates provided with drive electrodes and wall orientation layer and an optically anisotropic polymeric additional element. The... 

By far the majority of polymeric membranes, including UF membranes and porous supports for RO, NF or PV composite membranes, are produced via phase separation. The TIPS process is typically used to prepare membranes with a macroporous barrier, that is, for MF, or as support for liquid membranes and as gas-liquid contactors. In technical manufacturing, the NIPS process is most frequently applied, and membranes with anisotropic cross-section are obtained. Often,... 

Oligomeric phenylacetylene liquid crystalline derivatives capable of exhibiting a biaxial liquid crystal phase have been prepared. When these agents were functionalized with the polymerizable group 4-(4-acryloyloxybutyloxy)benzoic acid and then coated onto an alignment film and polymerized. An optically anisotropic retardation film was produced. 

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