Formation of Commercial Nylon 6 / Ring Opening Procedure
Sodium hydride is extremely moisture sensitive. It will react quickly with water to
release hydrogen gas. When handling NaH: Wear gloves, discard after this use. Do
not allow it to come into contact with water, moisture, sweat, skin, etc... Wear a lab
coat. And, as always wear safety goggles.
Remember: HOT glassware looks just like COLD glassware!!
Materials
5 g ε-Caprolactam
0.3 g Polyethyleneglycol
3 - 5 drops of N-Acetylcaprolactam
0.05 g Sodium Hydride
Procedure
1. Put the caprolactam, polyoxyethylene and N-acetylcaprolactam in a test
tube.
2. Heat the mixture above a one-inch flame while moving the test tube in and
out of the flame. Do not heat too long, just enough to melt! Remember
to always point the test tube away from yourself and others when
heating in this manner…no one wants molten caprolactam on their
skin!!
3. When the mixture in the tube has melted, add the sodium hydride to the
reaction tube. Make sure that all of the sodium hydride has reacted by
carefully tilting the test tube to contact any powder that might be clinging
to the side.
4. Heat this mixture for an additional 2-4 minutes until there is an apparent
increase in melt viscosity. Do not heat too long and keep the tube
moving to ensure even heating!
5. The reaction should be done about the time the reaction mixture starts to
reflux, or simmer. You will know it has polymerized because the mixture
will become much more viscous. If polymerization does not occur within
several minutes, cool to just above the solidification temperature, add
more NaH, and reheat.
6. You may be able to pull fibers from the molten polymer by placing a glass
stir rod in the tube and rapidly drawing out the solidifying material.
