INDEX elongation

While the shape factor, introduced in the previous section, provides a quantitative definition or description of particle shape, there are other descriptors such as flakiness ratio, flakiness index, elongation index and angularity number which are also found to be in vogue. 

Since the desired shape of a pellet is a sphere, shape factors have been used to describe the pellets. These are characterized variously as sphericity, roundness, shape coefficient, elongation index, and aspect ratio (63-67). Using the volume diameter, d, and projected diameter, d, a good measure... 

Is the elongation index according to Falcone et al. (2004b), Benn (1994) and Ryan and Ketcham (2002). This parameter indicates the degree of elongation of the MILv ellipsoid and it is related to the solid phase spread around the tertiary orientations of the cell walls, (<33). 

It is a complex index of anisotropy and takes into account both the isotropic index and the elongation index of the structure. 

Fig. 61. Size and shape analysis of synaptic vesicles in S-type and F-type synapse. Diameters of both major and minor axis in each synaptic vesicle in both types of synapses were measured. Ordinate shows the length of the major axis, while the abscissa that of the minor axis of vesicles in each type of synapse. Diameters of vesicles in S-type synapse (white) are distributed around the 45-degree line between ordinate and abscissa, while those in F-type synapse (black) of both white and black circles indicates the relative frequency of occurrence. Elongation index ratio of average length of major versus minor axis of vesicles in S-type synapse was about 1.2, while that of F-type synapse was about 1.7. Uchizono (1965).

Figure 12.8 shows the (PPE) curves (see 12.3.3) for the rotation of flat molecules, (in the rigid environment approximation). An elongation index is defined as D /D (see 12.2.3.1), the ratio of the two molecular dimensions in the molecular plane. The rotation is severely hindered if the elongation index exceeds about 1.3. A large molecule such as coronene rotates easily in the crystal, due to its very small elongation index. For these molecules, the ease of molecular rotation in the solid depends more on molecular shape than on details of the crystal structure. 

Fig. 12.8. (PPE) profiles for molecular rotation in crystals of some aromatic hydrocarbons. 1 anthracene (elongation index 1.57) 2 pyrene (1.27) 3 naphthalene (1.24) 4 benzene (1.10) 5 cor-onene (1.00)...

Material Percent neutralized Melt index at 190°C, dg/min Secant modulus, % extension, MPa Ultimate tensile strength, MPa Elongation at break, %... 

The more quickly and completely a fiber recovers from an imposed strain, the more nearly perfectly elastic it is. The ratio of the instantaneous elastic deformation to the total deformation may be used as a criterion of elasticity (62). The integrated divergences from a theoretical graph of perfect elasticity versus elongation is also used as a criterion for determination of the elasticity index. 

Figure 10.7. Effect of density and melt flow index on elongation at break. (Separation rate 45 em/min on specimen of 1 in gauge length.) A, constant density (0.92 g/cm ). B, constant MFI (0.7). C, constant density (0.94 g/cm ). (Reproduced by permission of ICI)...

Figure 12.21. (c) Elongation at break, (d) Macklow-Smith flow index. (The Distillers Company... 

Mechanical properties, such as elastic modulus and yield point, that depend on crystallinity per se are not seriously affected by low to moderate doses of ionizing radiation. On the other hand, those mechanical properties that are sensitive to interlamellar activity are most dramatically affected by the low to moderate radiation doses. This is seen in the ultimate tensile strength and elongation at failure of the polyolefins. It is also reflected in the large change in melt index between 0 and 18 Mrad, which indicates formation of cross-links that increase with increasing... 

Figure 6. Chromatism is due to the wavelength dependence of the index of refraction and produces coloured, diffuse and/or elongated images. For simplicity reasons, the off-axis image in the figure above is shown with pure lateral chromatism in reality both axial and lateral chromatisms would combine.

Relative to specimens examined under the microscope, the a or fast axis corresponds to the direction of the minimum refractive index, the minimum dielectric constant, and the maximum velocity. The y or slow axis corresponds to the maximum refractive index, the maximum dielectric constant, and the minimum velocity. Occasionally, a (3 axis is recognized with intermediate properties between a and y. When working with elongated bireffingent structures, birefringence usually is taken as positive when the y axis is parallel to the longitudinal axis. 

A certain anisotropy of the refractive index along specific crystallographic axes indicates that the microstructures in the porous network are not spherical but somewhat elongated along the PS growth direction [Mi4], This birefringence is below 1% for micro PS, while it may reach values in the order of 10% for meso PS films formed on (110) oriented silicon wafers [Ko22]. 

Therefore, uniaxially oriented samples should be prepared for this purpose, which give so-called fiber pattern in X-ray diffraction. The diffraction intensities from the PPX specimen of P-form, which had been elongated 6 times at 285°C, were measured by an ordinary photographic method. The reflections were indexed on the basis of the lattice constants a=ft=2.052nm, c(chain axis)=0.655nm, a=P=90°, and y=120°. Inseparable reflections were used in the lump in the computation by the least square method. 

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