Kebab epitaxial growth

Supramolecular structures formed during the crystallization of the melt under a tensile stress have already been described by Keller and Machin25. These authors have proposed a model for the formation of structures of the shish-kebab type according to which crystallization occurs in two stages in the first stage, the application of tensile stress leads to the extension of the molecules and the formation of a nucleus from ECC and the second stage involves epitaxial growth of folded-chain lamellae. 

Shish-kebab formation is a special case of epitaxial growth. The oriented growth of one crystalline substance on another is defined as epitaxy. 

The epitaxial growth and the formation of a shish-kebab stmcture were also investigated in high molecular weight iPP (HMW-iPP)/low-molecular-weight LLDPE (LMW-LLDPE) blends [21]. The formation of the initial crystallization precursor structure was investigated by using synchrotron WAXS/SAXS techniques at 130 and 140 °C. Shear was applied at temperatures above the cloud points of these blends, and therefore, the HMW-iPP chains could form a flow-induced crystalline stmcture in the blends only at 6 and 9 wt% of HMW-iPP LMW-LLDPE merely served as the amorphous matrix (Fig. 5.3). When the HMW-iPP... 

Figure 3.19. Schematics of shear-induced crystallization in PPS (a) random coil, (b) shear-induced molecular chain orientation, (c) shear-induced row nucleus, and (d,e) epitaxial growth of kebabs. [Adapted, by permission, from Zhang, R Min, M Gao, Y Lu, A Yu, X Huang, Y Lu, Z, Mater. Lett., 62, 1414-17, 2008.]...

Brinkmann M, Chandezon F, Juhen-Raban C, Pansu RP. Epitaxial growth of highly oriented fibers of semiconducting polymers with a shish-kebab-hke superstructure. Adv Funct Mater 2009 19 2759 2766. 

When the melt or the solutions are stirred epitaxial crystallinity is usually observed. One crystalline growth occurs right on top of another. This arrangement is often caUed shish-kebab... 

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