Dielectric studies of dipolar relaxation processes in nylon 11

The dielectric properties of semicrystalline nylon 11 (mixture of γ and α phase, degree of crystallinity 62%) were investigated in wide ranges of frequency and temperature by broadband dielectric relaxation spectroscopy, thermally stimulated depolarization current techniques and triangular voltage measurements. The main interest was focused on characterizing the relaxation processes in nylon 11, so measurements were, in general, limited to temperatures lower than about 100 °C. The secondary γ and β relaxations, in order of increasing temperature in isochronal measurements, the primary α relaxation, associated with the glass transition of the amorphous polymer, and a process at about 95 °C, related to a structural phase transformation from triclinic α phase to pseudo-hexagonal γ phase, were observed and studied in detail. Absorption of water was found to have a significant effect on the secondary relaxations, giving, in particular, rise to splitting of the β relaxation into two relaxations, β 1 and β 2 in order of decreasing temperature in isochronal measurements. The γ relaxation is assigned to the motion of methylene sequences involving adjacent dipolar amide groups and the β relaxation to motion of water-polymer complexes of different molecular configurations.