Poly , spherulitic structure

Recent developments have allowed atomic force microscopic (AFM) studies to follow the course of spherulite development and the internal lamellar structures as the spherulite evolves [206-209]. The major steps in spherulite formation were followed by AFM for poly(bisphenol) A octane ether [210,211] and more recently, as seen in the example of Figure 12 for a propylene 1-hexene copolymer [212] with 20 mol% comonomer. Accommodation of significant content of 1-hexene in the lattice allows formation and propagation of sheaf-like lamellar structure in this copolymer. The onset of sheave formation is clearly discerned in the micrographs of Figure 12 after crystallization for 10 h. Branching and development of the sheave are shown at later times. The direct observation of sheave and spherulitic formation by AFM supports the major features that have been deduced from transmission electron and optical microscopy. The fibrous internal spherulite structure could be directly observed by AFM. 

Studies have been conducted on poly (tetramethylene oxide )-poly-(tetramethylene terephthalate) -segmented copolymers that are identical in all respects except for their crystalline superstructure (66,67,68). Four types of structures—type I, II, and III spherulites (with their major optical axis at an angle of 45°, 90°, and 0° to the radial direction, respectively), and no spherulitic structure—were produced in one segmented polymer by varying the sample-preparation method. Figures 10 and 11 show the stress-strain and IR dichroism results for these samples, respec-... 

Spherulite structures typical for poly(ethylene glycol), which was used to form soft segments, with regions of lamellar crystal bundles radiating from the center of a spheralite were observed in graphene nucleated PU. ... 

Figure 9.4 Spherulite structure in poly(butane-l) after impingement/...

Spherulites are considered to be the polymer analogue of grains in polycrystalline metals and ceramics. Flowever, as discussed earher, each spheruhte is really composed of many different lamellar crystals and, in addition, some amorphous material. Polyethylene, polypropylene, poly(vinyl chloride), polytetrafluoroethylene, and nylon form a spherulitic structure when they crystalhze from a melt. 

Carr, S. H., Geil, P. H., Baer, E. The development of spherulites from structural units in glassy poly(bisphenol-A-carbonate). J. Macromol. Sci.-Phys. B2,13-28 (1968). 

Li L-S (1986) On the morphology and structure of poly(p-phenylene terephthalamide) single crystals and spherulites. J. Macromol. Sci.-Phys., B25 215... 

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