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A spherical body or coarsely crystalline aggregate having a radial internal structure arranged about one or more centers.



a small sphere consisting of an aggregate of very fine acicular crystals radiating from a central point. Spherulites are found in magmatic and sedimentary rocks and vary in mineral composition and size. In magmatic rocks, spherulites are usually interpreted as endogenic contact formations in the marginal sections of diorites. In acidic lavas, they may occur through consolidation when the primary glassy mass cools; in basic lavas (variolites), such formations are called varióles. Spherulites also form in gas bubbles of already hardened rock during secondary precipitation of zeolites, quartz, and similar minerals; in such cases they may be called pseudospherulites. Carbonate, iron-manganese phosphate, chalcedonic, and other types of spherulites are found in sedimentary rocks. They usually result from the crystallization of material in colloidal nodules, and many are close in origin to concretions.

References in periodicals archive ?
As mentioned above, the experimental results indicate a very peculiar influence of PPC on the kinetics of PLA spherulite growth, which is the main novel result detailed in this manuscript.
24] reported the stereocomplex crystallization and spherulite growth behavior of symmetric poly (L-lactide)-b-poly (D-lactide) with the molecular weights from 3.
In order to show the effect of the addition of PDLA on the isothermal crystallization behavior, the diameter of the PLLA spherulite against time is plotted in Figure 3.
It can be concluded that the spherulite and crystallite structure as well as the degree of crystallinity are affected by processing.
This is because the virgin PA6 forms the big spherulite during the homogeneous nucleation and just few crystal nuclei grow up for the molecular chains.
Janeschitz-Kriegl and Ratajski [29] proposed the existence of dormant nuclei that were unable to transform into spherulites affecting the rheological behavior before the appearance of crystallites.
The growth phenomenon is evaluated by measuring spherulite radius evolution against time.
Larger number of nucleating spherulites can be seen, which leads to an early impingement of the spherulites with each other and results in smaller size.
This will facilitate the movement of chains from amorphous phase to the existing crystal surface leading to faster spherulite growth rate (G) and higher crystallinity.
It is well known that high crystallization peak temperatures, high transparency, and good mechanical properties are associated with small spherulite size.