Crystallites lamellar structure

Nylon crystallites consist of sheets of chains that are hydrogen-bonded to their neighbors. On a supermolecular scale, crystallites have a lamellar structure, that is they are many times longer and broader than they are thick. When nylon crystallizes from an isotropic molten state, it generally forms spherulites, which consist of ribbon-like lamellae radiating in all directions... 

Usually, the encapsulated compound is present in a finely dispersed state, distributed aU over the polymeric matrix or in aggregates of different size, up to small crystallites (see above). Tetramethylhepandionato lanthanide (Ln(tmhd)3) complexes, on the other hand, were found to generate spherical lamellar structures that resemble nano-onions [53] when used in a miniemulsion polymerization process with acrylate monomers. Although the exact mechanism of the layer formation and the exact composition of the layers remain the subjects of ongoing research, some facts have become evident. The special triangular-prismatic geometfy of... 

Wide angle X-ray scattering was used to examine crystallite orientation, small angle scattering to determine the orientation of any lamellar structure, infra-red dichroism to study the orientation of non-crystalline regions, and nuclear magnetic resonance to record molecular mobility. 

Annealing and hot drawing have the effect of relaxing the material between crystallites, and frequently a clear lamellar structure is produced. When this occurs mechanical properties are sensitive to the lamellar geometry, and a full understanding is dependent on more detailed knowledge of lamellar structure. 

The epitaxial effect of the KBr surfaces on the nucleation of the y-form crystallites in poly(vinylidene flnoiide) was observed. The acceleration mechanism for y-form crystallization is unknown.It is known that the crystal lattice matching should induce the epitaxial growth of the y-form crystallites on the surfaces of KBr particles. The y-form crystals grow on KBr surfaces with the edge-on lamellar structure, because the lattice of... 

The most prominent structural entity in a material crystallized from a polymer melt is the spherulite. Electron microscopic evidence clearly shows that sphemlites are aggregates of lamellar crystallites and the lamellar structure persists throughout the body of spherulites. Spherulites are spherical... 

The spherulite lamellae also contain low-angle branch points, where new lamellar structures are initiated. The new lamellae tend to keep the spacing between the crystallites constant. 

Diblock copolymers with the length of E fixed at 40 units and that of P increasing from zero to 11 units were studied [57]. The thickness of the crystalline portion of the lamellar structures that formed was about 25 ethylene oxide units. The crystallites are, therefore, of close to extended form, but not completely so. A small, but... 

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