Nano-oriented crystals

We crystallize well-known large spherulites at quiescent field (e = 0s ) (Rg. 4.17a). The mean diameter (d) of the spherulites is rf 1.5 x 10 pm. When e increases, d becomes as small as several tens of pm (Hg. 4.17b,c). 

When e becomes larger than 200 s, most morphologies change from spherulites to a new form (Hg. 4.17d and e). The crystal size became too fine to be detected by POM, which suggests that NOCs have been generated. Detailed evidence of formation of the NOCs appears in Section 4.5.33. The characteristic colored pattern (corresponding to the retardation [37]) indicates that molecular chains orient along X- and / -axes for the ID and 2D compressions, respectively. Therefore, the 

Although shear should exist in the interface between the sample and plates, we do not detect different morphology, such as skin in the interface of the sample by means of OM, X-ray scattering, or TEM. Rgure 4.18 shows typical s dependence of crystallization behaviors as a function of crystallization time (t) observed by POM. We directly observe the so-called induction time (t), defined as the onset of crystallization by POM [38]. The Tc is as high as 150 C. 

In the crystallization under quiescent field (e = 0 s ), we observe nuclei at about 40 minutes crystallization ceases after 21 hours (Fig. 4.18a). Therefore, t = 40 minutes for = 0. 

For the crystallization at e 60 s we observe nuclei at T = 10 minutes crystallization (=formation of spheru-lites) ceases after 11 hours. Rgure 4.18b shows a typical example for e(S) = 3 s Therefore, the crystallization accelerates shghtly under a weak elongational field. 

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Okada, K.N. et al. (2010). Elongational crystallization of isotactic polypropylene forms nano-oriented crystals with ultra-high performance. Polymer Journal Vol. 42 (2010), pp.464-473... 

When the elongational strain rate e becomes larger than a critical value (e ), the crystallization behavior, structure, and physical properties change discontinu-ously. In the case of s larger than e, we obtain a morphology we call nano-oriented crystals (NOCs). The NOCs show high crystallinity (nearly equal to unity) and ultrahigh performance. 

In the second strategy, oriented crystallization of polyolefins, the production of in situ polyolefin (nano)fibers or (nano)sheets affords molecular polyolefin composites and effective polyolefin matrix reinforcement without requiring any alien fiber or fillers. Moreover, polyolefin reactor blends containing ultrahigh molecular weight (UHMW) polyolefin can produce in situ UHMW polyolefin... 

Phthalocyanines exhibit high polymorphism, as well [7]. They are insoluble nano crystalline materials, which produce poor x-ray powder diagrams with high preferred orientation and have been intensely investigated by electron microscopy and diffraction [8]. From copper phthalocyanine (CuPc) (Fig.2) nine polymorphs (a, P, y, 5, s, n, p, (, a and R) are known, but only the most stable P phase could be solved by single crystal x-ray diffraction [9] (P2i/c a=14.628 A, b= 4.790 A, c= 19.07 A, b=120.93°). 

Electron transport properties of metal oxides nanoparticles are very important for electrical and electronic applications as well as for understanding the unique one-dimensional carrier transport mechanism. It has been noticed that the diameter of metal oxides nanoparticles, surface conditions, crystal structure and its quality i.e., chemical composition, crystallographic orientation along the film axis etc are important parameters that influence the electron transport mechanism. It is found that conductance of a nano-structure strongly depends on their crystalline structure. For example, in the case of perfect crystalline Si nanowires having four atoms per unit cell, generally three conductance channels are found [51], One-or two-atom defect, either by addition or removal of one or two atoms may disrupt the number of such conductance channel and may cause variation in the conductance. It has been observed that change in the surface conditions of the nanowires can cause remarkable... 

Its topography reveals the unique structure consisting of aligned prisms or rods with 5pm diameter that extent approximately perpendicular from the dentin-enamel junction towards the tooth surface. Each rod consists of tightly packed carbonated hydroxyapatite crystals with very high aspect ratio. Nano-indentation studies revealed a pronounced anisotropy as the stiffness differs parallel and perpendicular to the rod extension. Even so, different fibre orientation on a micro level as shown in Figure 3.4b account for a quasi-isotropic behaviour. 

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