Small-angle light scattering spherulite structure study

Electron microscopy (5,40,52,63, 64), on the other hand, can provide direct information on the domain structure under favorable conditions, such as when the domains are crystalline. When the samples exhibit a semicrystalline superstructure, small-angle light scattering and polarized microscopy have been used in addition to electron microscopy to study the spherulitic structure. These methods are complemented by differential scanning calorimetry, and various techniques for studying dynamic mechanical behavior which can be interpreted to give additional, if somewhat less direct, information on domain structure. 

The growth and the structure of spherulites may also be studied by small-angle light scattering. The sample is placed between polarizers, the laser beam is passed through, and the resultant scattered beam is photographed. When the incident radiation is vertical in polarization but the analyzer is horizontal (crossed nicols), an Hv pattern is obtained as shown by Figure 11.7. 

Crystallization of a semicrystalline block copolymer quenched from the melt will also be briefly reviewed. Chu and Hsiao [68] comprehensively reviewed recent developments in SAXS where they discussed simultaneous measurements with other techniques. Among recently developed techniques, we will focus on simultaneous SAXSAVAXS (wide-angle X-ray scattering) and/or Hv-SALS (depolarized small-angle light scattering) measurements [69,70] because these are powerful techniques to study crystallization and spherulitic higher-order hierarchical structures in semicrystalline block polymers [71,72]. Current developments will also be reviewed later in the subsection on semicrystalline block polymers. 

By means of several optical techniques, viz. small angle laser light scattering (SALLS), optical microscopy, etc, the spherulite structure can be studied. From the photographic scattering pattern the spherulitic radius, R, can be calculated as a function of the crystallization time and/or blend composition [Stein, 1964] ... 

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