Domain contrast, electron microscopes

Microscopy. This is a powerful tool for studying visually the distribution of the two phases in the polyblend. One can tell not only the domain size of the dispersed phase but also which polymer forms the dispersed phase from refractive index. A phase contrast light microscope can detect heterogeneity at the 0.2-10 /x level. If the sample can be stained preferentially and sectioned with microtome, then under favorable conditions electron microscopy can show heterogeneity to a very fine scale. In a study of PVC-poly(butadiene-co-acrylonitrile) blend,... 

An alternative method is to use mixtures of concentrated sulfuric acid and potassium permanganate, giving contrast between crystals and amorphous domain that turns out to be applicable to many different polymers, e.g. polyethylene, polypropylene, poly(but-l-ene), polystyrene and poly(aryl ether ketone)s. The strong etchant degrades the amorphous phase more quickly than the crystals and the resulting topography is revealed by heavy metal shadowing. Replicates are prepared which are examined in the electron microscope. 

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