5. There is a large decrease in the bulk of the rope of Nylon-6,10 upon drying. Explain this observation. 6. Using full structural formulas, draw a typical portion of a Nylon-6,6 molecule; that is, expand a portion of the formula given in Equation 22.15. Show at least two hexanedioic acid units and two 1,6-hexanediamine units. 7. Draw formulas that illustrate the hydrogen bonding that may exist between two polyamide molecules after fibers have been “cold-drawn.” 8. Nylons undergo depolymerization when heated in aqueous acid. Propose a reaction mechanism that accounts for this fact, using curved arrows to symbol- ize the flow of electrons. 9. Nylon-6 is produced from caprolactam by adding a small amount of aqueous base and then heating the mixture to about 270 °C.