The structure of a spherulite was illuminated in an experiment performed over 30 years ago, in which isotactic polypropylene was crystallized in a sample that also contained atactic polypropylene, with the ratio 1:9. After crystallization, the amorphous atactic polypropylene was removed by a solvent that did not disturbed the crystallized isotactic polypropylene, leading to a visualization of the structure of the crystalline material (PC Fig. 7.30, reproduced from Keith, H. D.; Padden, F. J. J. Appl. Phys. 1964, 35, 1270).
PC Fig. 7.31 depicts a schematic representation of the growth of a spherulite, and the next figure is a magnification of a small portion to show the location of chain folded material. The chain fold is much less regular here than in material crystallized from dilute solution. A small number of chains (tie molecules) cross from one lamella to another. These tie chains are important for the toughness and plastic deformation of certain polymers.
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