General Safety Guidelines
The Chemistry of Nylon 6 Synthesis
Answers to Discussion

Safety and Alternative Activities

Because this activity uses sodium hydride and open flame, some school districts may not allow students to carry it out. So this activity can be carried out as a demonstration in such circumstances.

If you would still like your students to carry out a polymerization which is related to the story of Wallace Carothers, a very safe and easy to use activity kit called "Pull'n Polymers" is available from The Wild Goose Company. Students synthesize linear and crosslinked polyesters using only nontoxic starting materials. The company can be reached by telephone at 1-888-621-1040. This activity is relevant not only because the chemistry of polyester synthesis is very similar to that of polyamide synthesis, but also because Carothers actually synthesized polyesters before polyamides.

Sodium hydride must be kept completely dry and away from water at all times. Fire may result when sodium hydride contacts water. Do not let the students handle sodium hydride themselves.

Although no special handling procedures are required for the other reagents in this procedure, remember to handle them with the same caution you would any other laboratory materials.

Preparation

This procedure requires little preparation other than making the materials available to the students.

Procedure

Make sure the students never point the open ends of test tubes at anyone when the tubes are hot. Splattering may cause burns if they do.

When drawing out the nylon 6 filaments, students may want to go into a hallway to see how long a filament they can draw. Filaments can easily be more than 75 feet long.

Extension

Varying the amount of sdium hydride initiator will affect the average molecular mass of the polymer chains produced. Each molecule of NaH initiates one chain of nylon 6 polymer. Therefore, the less NaH there is in the reaction mixture, the fewer growing polymer chains there will be competing for caprolactam monomer molecules. Lowering the amount of NaH used will then increase the average molecular mass of polymer chains finally produced. Likewise, rasing the amount of NaH will decrease the average molecular mass.

In general, the quality of the fibers icreases with increasing molecular weight. Therefore, lowering the amount of NaH initiator will result in better fibers which can be drawn to longer lengths. Increasing the amount of NaH used in the reaction will result in poorer quality fibers which break at shorter elongations.

Relevant National Science Education Standards

Unifying Concepts and Processes — The experiment involves understanding of the workings of a complex polymerization system.

Physical Science — Chemical reactions and molecular structure are central to the activity.

Science and Technology — The activity explores an alternative technology to that which Wallace Carothers invented.

History and Nature of Science — The curious history of nylon 6 is explored in the activity, clearly showing the influence of human fallibility on the development of science and technology.