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62 . Spotlight 200 User's Guide
Filled polymers
When a polymer contains a high concentration of fillers, and you want to analyze the
polymer, you have to prepare a sample for analysis that is free of filler.
Often you can obtain a suitable sample by cutting a thin wedge of the material with a sharp
blade. If the filler is not uniformly dispersed, you can find clear regions of polymer for
analysis.
You can use pyrolysis to remove the fillers. As you heat the sample, the polymer volatilizes,
and the fillers are reduced to ash. The sample can be pyrolyzed in the following ways:
Using a disposable pipette:
1. Place the polymer in a disposable pipette and seal the large end.
2. When this end cools, tap the polymer into it, then heat the sample gently.
The pyrolyzed polymer condenses on the walls of the pipette. The filler is left behind as
ash.
3. Score and break the pipette between the ash and the pyrolysate.
4. Add a drop of solvent to the pyrolysate to wash it on to a salt plate.
If the amount of sample is small, use a capillary tube instead of a disposable pipette.
Using a microbrush to pyrolyze micro amounts:
1. Seal the end that is away from the brush fibers and tap the sample particle into this end
then heat it gently with a microtorch.
2. After pyrolysis, break off and discard the end of the tube that contains the ash.
3. While holding the fibers of the brush against the salt plate, add a drop of solvent to the
broken end.
4. Allow the solvent containing the pyrolysate to flow into the fibers.
When it evaporates, the pyrolysate remains on the salt plate for analysis.
Particles
Crushing
Crushing enables you to thin samples such as large particles that cannot be sliced. This can
be done in various ways:
•
If the sample is small, crush it with the roller end of the roller knife.
If the sample is larger, use a pestle and mortar.
•
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