Orientation INDEX

The values of the amorphous orientation index in the form of Hermans function of orientation if a), determined by the authors for PET fibers are listed in Table 6. The differences in the values of fa quoted in Table 6 and referring to particular investigation methods can result from the fact that in some methods the orientation of the amorphous and mesophase are considered jointly. Consequently, in such a case the values of fa will be overrated. 

The problem of calculating the degree of orientation and size from a scattering pattern has been widely addressed in the scientific literature [86, 88]. In the study of regenerated tissues a two-dimensional analog of the Hermans orientation index [89, 90], previously used to specify the orientation of a polymer from X-ray scattering data, was adapted [81, 91]. 

The degree of orientation [91] was defined by an orientation index, S, which has an upper limit indicative of perfect orientation along a given axis and a lower limit corresponding to an ideally random orientation. A particularly useful definition for S is ... 

The final expression for S used to calculate the orientation index from experimental data is (see [81, 91] for derivation) ... 

Orientation index (OI). This factor is concerned with orientation of the polymer in the machine and... 

Orientation of the tube can be measured by x-ray diffraction. Practically, a comparison of the tensile yield strength of the tube in the two directions provides a measure of the orientation. The orientation index is, thus, defined as ... 

It can be seen that an orientation index of zero means that tube is randomly oriented, which is ideal. A value of one indicates that all orientation is in the longitudinal direction, which is the worst case. 

Orientation Index (01) - This is a factor that characterizes the orientation of polymers in polytet-rafluoroethylene tubing in machine and transverse directions. Orientation index (01) provides a numerical value to monitor the disparity of orientation ... 

One method used for studying the orientation of polymers which does not make use of electromagnetic radiation is that of sonic velocity or pulse propagation. This technique is particularly suited to the characterisation of orientation in fibres (or samples having rodlike geometry) and, although the technique suffers somewhat from not having a sound theoretical basis, it is of particular usefulness in instances where an orientation index or parameter is desirable for relative comparisons. 

The initial surface appearance of the zinc deposited at 500 A/m for 90 kC/m (3 minutes) was observed by SEM. The structure of the deposited Zn was analyzed by X-ray diffraction analysis (XRD) and the crystal orientation index was calculated by Wilson s equation (5). 

In the solutions containing gelatin, the morphology of the electrodeposits was also of the unorientated dispersion type. Consequently, the (002) orientation index of the deposited Zn depended on the overpotential for Zn deposition as shown in Fig.5(b). This result can be explained well by the Pangarov s two-dimensional nucleation theory (9) that the crystal orientation of the deposited metals is determined by the deposition overpotential of the metals. 

Fig. 1 Octahedral sites in the bcc lattice, labelled with a site orientation index = 1,2,3. The schematic energy diagram shown at the right emphasizes the equality of all site energies (and all saddle-point energies) in the unstressed perfect crystal. Both diagrams show that a nearest-neighbor jump automatically produces reorientation of the interstitial.

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Relatively simple WAXS method for estimating the MFA is a measurement the maximum intensity of the (200]-peak [/y], when the fiber is oriented vertically and minimum intensity of the peak [/jj], when the fiber is oriented horizontally. From the intensity measurements an orientation index F = 1 - (/h//v3 is found, and then average MFA of the fibers is calculated by the following equation ... 

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