Spherulite morphology

Figure 2. Plot of linewidth, W, against temperature at 67.9 MHz for two linear PE samples of same degree of crystallinity (0.51) but differing morphologies spherulitic, (Ono morphology ( ).

Keywords atomic force microscopy (AFM), structure, morphology, spherulite, hedrite, lamella, conformation, chain packing, films, scanning force microscopy (SFM), tapping mode, syndiotactic PP, (3-PP, transcrystallinity, corona treatment, biaxial orientation. 

Practical appHcations have been reported for PVP/ceUulosics (108,119,120) and PVP/polysulfones (121,122) in membrane separation technology, eg, in the manufacture of dialysis membranes. Electrically conductive polymers of polyaruline are rendered more soluble and hence easier to process by complexation with PVP (123). Addition of small amounts of PVP to nylon 66 and 610 causes significant morphological changes, resulting in fewer but more regular spherulites (124). 

We can nucleate crystallization from the melt by incorporating finely ground inorganic crystalline compounds such as silica. Nucleation of injection molded nylons has three primary effects it raises the crystallization temperature, increases the crystallization rate, and reduces the average spherulite size. The net effect on morphology is increased crystallinity. This translates into improved abrasion resistance and hardness, at the expense of lower impact resistance and reduced elongation at break,... 

Figure 15 Morphological map of linear polyethylene fractions. Plot of molecular weight against crystallization temperature. The types of supermolecular structures are represented by symbols. Patterns a, b and c represent spherulitic structures with deteriorating order from a to c. Patterns g and d represent rods or sheet-like structures whose breadth is comparable to their length g or display a different aspect ratio d. Pattern h represents randomly oriented lamellae. Neither h nor g patterns have azimuthal dependence of the scattering. Reproduced with permission from Ref. [223]. Copyright 1981 American Chemical Society. (See Ref. [223] for full details.) Note the pattern a is actually located as o in the figure this was an error on the original.

The formation of isolated FCSCls was confirmed from the melt of samples with different l (ECSCs-melt-FCSC or FCCs-melt-FCSC). The morphology is the same as the usual one of spherulite or axialite, as reported by Toda [47], irrespective of the morphology before melting. 

Fig. 29 Fractured morphology of spherulitic objects in a thin film of PET crystallized at 220 °C [36]. On the fractured surface many small particles with a diameter of 0.2 0.3 xm are seen while on the spherulite surface there is a fibril structure 0.2 05 xm thick... 

Morphology. Observations with the light microscope, under polarized light, showed that the end blocks in the case of both types of polymers crystallized in the form of the usual spheru-lites, but not as well as the analogous homopolymer, H2-l,4-polybutadiene. The formation of the spherulites was improved with increasing end-block content and/or higher molecular weight of the end blocks. 

It should be re-emphasized that although our block copolymers do not display spherulitic morphology when they are compression molded, they are nevertheless crystalline. Hence, this indicates that under this mode of film preparation, aggregation into well developed superstructure is apparently kinetically limited. 

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