Anisotropic rods

The crystals of indinavir sulfate exist as a mixture of anisotropic rods and... 

Fig. 31. Theoretical curves of the angular dependence of the anisotropic light scattering (vertical polarization detection of horizontal component) for a random collection of anisotropic rods of length L and diameter d, Eq. (IV-35) [Van Aartsen...

The texture of unoriented filins of PBLG is interpreted to be composed of randomly oriented anisotropic rods which are again composed of oriented aggregates of the polymer molecules by means of the small-ai e li t scattering 17) and the electron micrt aph 93). 

The GPC-viscometry with universal calibration provides the unique opportunity to measure the intrinsic viscosity as a function of molecular weight (viscosity law, log [17] (it versus log M) across the polymer distribution (curves 3 and 4 in Fig. 1). This dependence is an important source of information about the macromolecule architecture and conformations in a dilute solution. Thus, the Mark-Houwink equation usually describes this law for linear polymers log[i7] = ogK+ a log M (see the entry Mark-Houwink Relationship). The value of the exponent a is affected by the macromolecule conformations Flexible coils have the values between 0.5 and 0.8, the higher values are typical for stiff anisotropic ( rod -like) molecules, and much lower (even negative) values are associated with dense spherical conformations. 

Fig. 3.5 Structural hierarchy in liquid-crystalline fibers. The mechanical performance of highly oriented polymers can approach the ultimate theoretical properties at high degrees of elongation. Anisotropic, rod-like macromolecules, like aromatic copolyesters composed of 2,6-naphthyl and 1,4 phenyl units, often form oriented structures, which can exhibit liquid crystallinity. Extensive structural studies of fibers of these oriented copolyesters showed a hierarchical structure like the one depicted in this Figure. In aramids (Kevlar or Twaron) similar structures may exist. Adopted with permission from [17]...

Here, D stands for the characteristic geometrical length of the system. In the case of spherical particles or strongly anisotropic rod-like particles immersed in a nematic LC phase, D stands for the particle diameter or width, respectively. The strong anchoring regime, in which the surface-imposed tendency is... 

In this appendix we derive an expression for Iw and Ihv for a rigid, optically anisotropic rod of negligible thickness (cf. Section 8.9). 

The theory of the scattering from rods has been generalised to include the case of anisotropic rods by Rhodes and Stein who give, for example, for the Hy scattering intensity from a thin rod of length L lying in a plane perpendicular to the incident beam and tilted at an angle a with respect to the vertical direction (Fig. 45) ... 

Houwink Relationship, p. 1429). The value of the exponent a is affected by the macromolecule conformations Flexible coils have the values between 0.5 and 0.8, the higher values are typical for stiff anisotropic ( rod -like) molecules, and much lower (even negative) values are associated with dense spherical conformations. 

Figure 3 Theoretical H Scattering for a Random Collection of Anisotropic Rods Embedded in an Isotropic Matrix. L = length of the rods, Q = radius of the rods S in this Figure is a." - + 2otS. j. H. Gouda (l8 . ...

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