Morphology phase contrast optical microscopy

Initial morphologies of extruded strands were examined as a function of extruder rpm and blend composition. Phase contrast optical microscopy shows a 35% HDPE dispersed phase domain size to be comparable (1 p. < size < 5 p) at both 300 and 500 rpm, (Fig. 5.9). The effect of compatibilizer on domain size of the dispersed phase is shown in Fig. 5.10. 

Mann, S. Meyer, J. Dietzel, I., Integration of a scanning ion conductance microscope into phase contrast optics and its application to the quantification of morphological parameters of selected cells. Journal of Microscopy 2006, 224, 152-157. 

Microscopy provides detailed information about miscibility and about phase morphology, i.e. the actual geometry of the phases. Optical microscopy resolves structures down to about 1 im. The samples may need staining prior to examination. In other cases, where the refractive index mismatch is sufficiently large, direct examination can be made in the microscope using phase-contrast or interference-contrast optical microscopy. 

Optical microscopy on phase contrast mode allows observation of the different morphologies obtained for each PP/interfacial modifier/PA6 blend. By image analysis techniques, it is possible to carry out statistical field measurements not only of the mean number of particles on the dispersed phase but also of their preferential geometry, mean size, and size distribution. 

Optical microscopy allows assessment of dispersed phase morphology hut provides little information about the dispersion mediiun. In contrast, electron microscopy gives more comprehensive information on the morphology of the continuous phase. 

Electron Microscopy and Diffraction. When electrons penetrate through matter in an electron microscope, contrast is formed by either differential absorption (amplitude contrast) or by diffraction phenomena (phase contrast). Electron micrographs of catalyst materials can provide identification of phases, morphologies, and chemical composition in a spatially resolved manner. Image interpretations are often not straightforward and need expert analysis. Several variants of EM use different electron optics and working principles and therefore have to be chosen depending on the problem to be solved (21). 

In summary, this method is a two-dimensional variant of ellipsometry, which allows one to determine film thicknesses and optical properties of adsorbed monolayers. If the latter are known, one is able to deduce detailed morphological properties of the adsorbate films, such as molecular orientations or phase transitions. The lateral resolution is of the order of one micrometer, whereas thickness variations of the order of 0.1 nm can be deduced. The method is very different from phase-contrast microscopy since the phase domains themselves are imaged and not just the border lines (as in phase-contrast microscopy). 

For this purpose, the combination of an inverted optical microscope with an atomic force microscope on top has proved very useful (Fig. 9.2), especially in the biological sciences, where AFMs are nowadays a very important experimental tool (Morris et al. 1999). Note that the most versatile solution is an AFM which allows optical imaging also from the top via, e.g., phase contrast microscopy. This setup gives access both to transparent objects (fluorescence imaging from below) as well as nontransparent materials and is therefore also very well suited for simultaneous morphological and optical imaging of submicron scaled circuits and other elements of new solid state electronics. 

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