Crystalline structure and the unusual dielectric behavior of nylon 93

Large dielectric constants (390 for a slowly cooled sample, and 2400 for a quenched sample at 0.3 kHz) were measured for nylon 93. A displacement–electric hysteresis loop was obtained for a slowly cooled sample of nylon 93, and the remanent polarization was calculated to be 0.543 C m −2 for the slowly cooled sample at 75 °C. The structure of nylon 93 was investigated in detail to clarify the origin of these unusual electric properties. The infrared peaks assigned to the amide groups of nylon 93 were changed by a corona poling treatment, which suggests that the hydrogen bonds formed by the amide groups of nylon 93 were weak enough to allow the amide groups to be aligned by an external electric field. The results obtained by X-ray diffraction, polarizing optical micrography, and differential scanning calorimetry indicated that α- and γ-crystals were formed in the slowly cooled and quenched samples, respectively, and the γ-crystals in the quenched samples were gradually changed into α-crystals by annealing. Large dielectric constants were measured for nylon 93. A displacement–electric hysteresis loop was obtained for a slowly cooled sample of nylon 93. The structure of nylon 93 was investigated in detail to clarify the origin of these unusual electric properties. The results obtained by X-ray diffraction, polarizing optical micrography, and differential scanning calorimetry indicated that α- and γ-crystals were formed in the slowly cooled and quenched samples, respectively, and the γ-crystals in the quenched samples were gradually changed into α-crystals by annealing.