Morphology shish kebabs

D. Molecular Origins of Shish-Kebab Morphology Acknowledgments... 

The application of a flow field has pronounced effects on the crystallization dynamics and semi-crystalline morphology of polymeric systems. Under quiescent, no-flow conditions the crystallization dynamics is governed by the temperature, T, and spherulites are formed. In the presence of flow, increasing the flow rate can result in an increase of the nuclei density up to factors of 106, but the morphology remains spherulitic [18]. At even higher flow rates the so-called shish-kebab morphology is observed. This results from the de-... 

Information on how orientation during melt crystallization affects the transport properties of polymers is sparse however, increases in the permeability have been attributed to the "shish kebab" morphology (ill). Most of the work involving barrier properties of oriented semicrystalline polymers has dealt with materials drawn at temperatures well below the melting point. The transport properties of cold-drawn polyethylene (34f 42-46), polypropylene (42,42), poly(ethylene terephthalate) (12,42-4 9), and nylon 66 (22) among others have been reported. 

Shish-kebab" morphology (a different highly oriented morphology which develops when an oriented melt is crystallized)... 

Fig. 5.18 Shish-kebab morphology produced by stirring a 5% xyiene soiution of poiyethyiene at 510 rpm and 104.5 °C the scaie bar represents 1 pm. (Adapted by permission of John Wiiey Sons, inc.)...

Fig. 8.1. Schematic representation of flow-induced precursor structures at different stages (A) before shear, (B) formation of precursor structures containing linear nuclei (shish), (C) formation of shish-kebab morphology. (Reprinted with permission from [21])...

Epitaxial lamellar overgrowths are instrumental in production of complex morphological features. One of them is shish-kebab morphology. Shish-kebab morphologies are frequently observed in crystallizations from solution or melt under extensional strain or flow. ... 

Figure 3.19 shows phases of shish-kebab morphology formation. Apphcation... 

SCORIM results in substantial enhancement of the physical properties of iPR The enhanced properties are related to the formation of shish-kebab morphology, and hence the high levels of molecular orientation that result from the application of macroscopic shears to a solidifying melt in a mold cavity. In this chapter, SCORIM technology is first described, and then relationships between processing conditions and mechanical properties are discussed, including a discussion on shish-kebab morphology, orientation and the occurrence of 7 phase in processed iPP. 

SHISH-KEBAB MORPHOLOGY AND MOLECULAR ORIENTATION IN SCORIM MOLDINGS... 

Keywords injection molding, SCORIM, structure-propjerty relationships, shear-controlled orientation, molecular orientation, SCORIM pistons, impact strength. Young s modulus, shish-kebab morphology, y-phase, a-phase, p-phase. X-ray diffraction. 

Figure 5 Shish-kebab morphology in an oriented PP foil, short pieces of lamellae are arranged in parallel order perpendicularly to a backbone chemically stained ultrathin section, TEM micrograph.

DSC, WAXD, small-angle X-ray scattering (SAXS), and tunnel electron microscope (TEM) were employed to study the microstructure of biaxially self-reinforced HDPE prepared in uniaxial shear field by DPIM. The results indicate that the biaxial self-reinforcement of HDPE is mainly due to the existence of interlocking shish kebab morphology, the orientation of lamellae and molecular chains, along with the enhanced crystallinity. 

Shish kebab morphology was observed via SEM. For pme LLDPE, it seems shish is absent, and the regularity is low (Figure 23.18). While an obvious shish kebab structrue was... 

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