High-temperature dielectric relaxation in nylon 12 and the effects of annealing and absorbed water

Abstract

To understand the molecular origin for the high-temperature, lowest-frequency relaxation process in nylon 12, the dielectric behaviour of its water-saturated (16 mol% water) state has been studied at 423 K and over the frequency range from 12 to 10⁵ Hz. In addition, the effects of annealing at 423 K have been investigated by calorimetric and dielectric methods. The dipolar relaxation spectra, which have been resolved by the procedure described in the preceding paper (J. Chem. Soc., Faraday Trans., 1995, 91, 329), have an asymmetric distribution of relaxation times. The static permittivity remains constant on annealing for dry nylon 12, but decreases for a water-saturated sample whose relaxation time also decreases. It is concluded that the relaxation involves motion of protons over intermolecular barriers in the H-bond linkages. The decrease in the amount of amorphous phase and the change in the crystal forms on annealing have a greater effect on the dielectric behaviour when nylon 12 contains water.