Dielectric studies of dipolar relaxation processes in nylon 11

The dielectric properties of semicrystalline nylon 11 (mixture of gamma and alpha phase, degree of crystallinity 62%) were investigated in wide ranges of frequency and temperature by broadband dielectric relaxation spectrosco py, thermally stimulated depolarization current techniques and triangular v oltage measurements. The main interest was focused on characterizing the re laxation processes in nylon 11, so measurements were, in general, limited t o temperatures lower than about 100 degrees C. The secondary gamma and beta relaxations, in order of increasing temperature in isochronal measurements , the primary alpha relaxation, associated with the glass transition of the amorphous polymer, and a process at about 95 degrees C, related to a struc tural phase transformation from triclinic alpha phase to pseudo-hexagonal g amma phase, were observed and studied in detail. Absorption of water was fo und to have a significant effect on the secondary relaxations, giving, in p articular, rise to splitting of the beta relaxation into two relaxations, b eta(1) and beta(2) in order of decreasing temperature in isochronal measure ments. The gamma relaxation is assigned to the motion of methylene sequence s involving adjacent dipolar amide groups and the beta relaxation to motion of water-polymer complexes of different molecular configurations.