Cross-hatched structure

Morphological explanations for the improved ductility of the fl nucleated materials have focussed on the lamellar texture. That crazes in a iPP are more localised and better defined than in /3 iPP may reflect both the influence of the cross-hatched structure on lamellar slip described in the previous section, and the strong correlation between deformation in ft iPP and the local orientation of the lamellae with respect to the tensile axis. Indeed, the trend towards more localised deformation in a spherulites may simply reflect the relatively homogeneous lamellar textures of these latter [24]. 

Under defined conditions, the toughness is also driven by the content and spatial distribution of the -nucleating agent. The increase in fracture resistance is more pronounced in PP homopolymers than in random or rubber-modified copolymers. In the case of sequential copolymers, the molecular architecture inhibits a maximization of the amount of the /1-phase in heterophasic systems, the rubber phase mainly controls the fracture behavior. The performance of -nucleated grades has been explained in terms of smaller spherulitic size, lower packing density and favorable lamellar arrangement of the /3-modification (towards the cross-hatched structure of the non-nucleated resin) which induce a higher mobility of both crystalline and amorphous phases. 

FIGURE 5.29 Cross-hatch structure of winding layer (transmission electron microscope, TEM). 

Investigations by transmission electron microscopy (TEM) exhibit the known cross-hatched structure in the central layer but inside the oriented layers there are stacked lamellae. Their orientation is perpendicular to the flow direction of the polymer melt (Figure 2, upper side). The lateral range of these lamellae are shorter than the range of the radial lamellae... 

For the given cross-hatched structure it is no longer possible to employ the one-dimensional electron density correlation function and interface distance distribution function. Still applicable, because generally valid for two-phase systems, are the Porod-law (eq.(6) and the equation for the invariant ... 

Figure 3.12 Mass-thickness contrast in TEM micrographs of isotactic PP ultrathin sections due to selectively chemical staining of the amorphous regions and the boundaries between the lamellae (a) a - iPP with the typical cross-hatched structure of lamellae and (h) - iPP with a bundle of parallel lamellae (compare also with Fig. 3.9).

This difference is reflected in the morphologies of samples. Figure 8.17 shows TEM micrographs of all samples. A typical thick lamellar structure is observed for iPP-IC. For iPP-PMQ and iPP-MQ, thinner lamellae than iPP-IC and a cross-hatched structure are observed. On the other hand, iPP-POW has no lamellar structure, which means the crystalline component is... 

Structure shown in the AFM image indicates that the PEA lamellae are ca. 66.5° apart from the chain direction of the PE substrate crystals. It causes a 23.5° inclination of the PEA chains with respect to its lamellar normal direction. This is reasonable when the lamellae with 00/ fold surfaces are considered. As illustrated in the right part of Figure 12.12, a chain folding in the 001 surface leads exactly to the formation of PEA lamellae 66.5° apart from the chain direction of the PE substrate crystals. This cross-hatched structure should take the response from a remarkable property improvement of the PE/PEA system reported in Ref. [100], as also found for the PE/iPP system [101,102] which is discussed later. 

Plant cell walls are made of bundles of cellulose chains laid down in a cross-hatched pattern that gives cellulose strength in all directions. Hydrogen bonding between the chains gives cellulose a sheetlike structure. 

Fig. 8. Projections along the c axis of details of the structures of 8 and 2 with ethano and methano syn bridges (cross-hatched rectangle), respectively. The differing proximity of the syn bridge to the methyl substituents (cross-hatched triangles) on the flanking anti walls of the canal are apparent81...

Figure 113 Schematic crystal structure of one layer of talc. Such layers are stacked to make the complete structure. The large and medium open circles represent oxygen atoms.The cross-hatched large circles represent hydroxyls (OH).The small open circles represent magnesium atoms (Mg) and the cross-hatched small circles represent silicon (Si) atoms. Figure is reproduced from Bragg, Claringbull and Taylor (1965).

Fig. 2 Cationic structure of 2. a Metal skeleton, b Structure of one of the faces of the octahedron, c View of the structure of one of vertices of the octahedron. Cu filled circle Ln circle with cross-hatching...

Figure 1. The organization of catalytic and non-catalytic domains in cellulases from C. fimi and other bacteria. CfCenA, B and C, and CfCex are the endo- and exo-p- 1, 4-glucanases of C. fimi, ClfX is a translated open reading frame from Cellulomonas flavigena (29), CtEGD and PfEndA are endo-p-1, 4-glucanases from Clostridium thermocellum and Pseudomonas fluorescens, respectively (30,31), The primary structures are drawn approximately to scale and are numbered from the amino terminus of the mature protein ClfX is numbered from the start of the open reading frame. Unshaded areas represent catalytic domains, cross-hatched areas indicate cellulose-binding domains, repeated blocks of amino acids are stippled, and black areas represent linker regions.

Fig. 7. Schematic representation of four procedures commonly used to sample a field in stereo-logical analysis. These procedures have been used to study the porous structure of collagen-GAG matrices [74] and yield values for average pore diameter, pore volume fraction and other features. In this illustration, a phase A (cross-hatched) is embedded in a continuous phase B (white background). A Random point count B systematic point count C areal analysis D lineal analysis. (Reprinted from [64] with permission).

Fig. 30. The total differential oscillator strength for benzene including the structure factor but neglecting any vibrational effects. The cross-hatched portion of the figure represents the transition to a continuum orbital of e2ll symmetry, while the remainder is for a transition to an elu orbital. The positions of higher ionization thresholds are indicated.

Figure 8. Structure of tra/M- Re4Os2Se8[CNCu(Me6tren)]6 9+. Black, hatched, large shaded, cross-hatched, small shaded, and white spheres represent Re, Os, Se, Cu, C, and N atoms, respectively H atoms have been ommitted for clarity. Note that this assembly occurs together with the cis isomer in a 2 1 ratio, and that the Re and Os sites could not actually be resolved crystallographically.

FIGURE 26 Framework of [Na C AS4W40O140]27- as an assembly of four ASW9O33 groups linked by (W02) groups (gray spheres). The sodium cation occupies the nominal 8-coordinate Si site at the center of the structure. The cross-hatched oxygen atoms identify one of the four S2 sites. 

Fig. 3. Electronic band structure of Cu projected on the (111) surface Brillouin zone. The cross-hatched region is the projected bulk continuum of states. The Shockley surface state derived from the s-p band (broken line) lies in the L-gap around the Fermi level.

Figure 1. Diagram showing the core structure of compound la, CpWIr3-(CO)7( i3, T 2-C2Ph2)2 The cross-hatched circles indicate the ipso carbons of the substituent phenyl groups.

The ideas underlying elemental structures models are to establish microstructures experimentally, to compute free energies and chemical potentials from models based on these structures, and to use the chemical potentials to construct phase diagrams. Jonsson and Wennerstrom have used this approach to predict the phase diagrams of water, hydrocarbon, and ionic surfactant mixtures [18]. In their model, they assume the surfactant resides in sheetlike structures with heads on one side and tails on the other side of the sheet. They consider five structures spheres, inverted (reversed) spheres, cylinders, inverted cylinders, and layers (lamellar). These structures are indicated in Fig. 12. Nonpolar regions (tails and oil) are cross-hatched. For these elemental structures, Jonsson and Wennerstrom include in the free energy contributions from the electrical double layer on the water... 

To illustrate In (Fig. 26) the effects of iodine number and structure on both running temperature and modulus are combined. If structure is held at a constant level and the iodine number is varied, running temperature and modulus change simultaneously. Both running temperature and modulus increase with increased structure. The cross-hatched area in the center of the graph is the specification for a grade of ISAF. This area thus becomes a target area for quality control for a black with the particle size dictated by N-220. 

Here, again, at fixed particle size, modulus is a function of both iodine number and structure, but extrusion swell is a function of structure only. The cross-hatched area is the quality control target area for that particular black to be in specification. 

Fig. 10.38. The structure of DyfPPP) (from Ref. [124]). The cross-hatched circle represents Dy3+, the dark circles phosphorous, and open circles oxygen.

A population of individuals is required for the EA to work on, so let us begin by making that. A portion of our random starting population of lighthouses is shown in Fig. 4, in which light-emitting blocks are shown cross-hatched and structural building blocks are shaded. 

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