Limiting Artifacts in Microtomy

Sectioning problems, collection, and troubleshooting are all described by Reid [115]. For example, artifacts have been observed in ultra-microtomy of liquid crystal polymers, when compared with x-ray diffraction, due to compression that modified the structure of the polymer [163]. The oscillating diamond knife, discussed earlier, is also intended to reduce compression of ultrathin sections [118]. The list in Table 4.2 is not complete but is intended to provide insight into the cause and potential remedy of sectioning problems [164]. 

Image contrast in TEM is the result of variations in electron density among the structures present. Unfortunately, most polymers in 

Dyes and dye mixtures are used for identification of textile fibers, and their distinctive cross sectional shapes aid identification by light microscopy [172]. Water soluble dyes have been used with PS films imaged by energy loss 

the most common methods of observing multiphase polymers are by phase contrast OM of thin sections, TEM of stained ultrathin sections, SEM of etched or fractured surfaces, and SPM of microtomed or etched surfaces. Osmium and ruthenium tetroxide are the most commonly used stains for observation of the dispersed phases in multiphase blends, whereas other stains have more limited application. Detailed fine structure of polymers is also made 

Staining of polymers can be conducted either before or after sectioning. The sample is cut into small blocks, about 1-3 mm across, and immersed in the stain solution or exposed to the vapor. Materials can be embedded and the blocks faced and then stained, especially when the stain diffuses into the polymer slowly. This method permits the sectioning and collection of the near surface material, which is the most thoroughly stained. If sections can be cut prior to staining, then they are stained either in the vapor, immersed in the solution, or placed on the surface of a stain droplet. 

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