Dielectric measurements of N-(p-methoxybenzylidene)-p-butylaniline in the frequency range 1 kHz to 120 MHz

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Abstract
Dielectric measurements on the nematic phase of N-(p-methoxybenzylidene)-p-butylaniline (MBBA) magnetically aligned with the long molecular axis parallel to both the magnetic and electric fields show the presence of an absorption with a relaxation time at (300 K) of 10.1 × 10–8 s and a dipole component of (2.3 ± 0.2)× 10–30 C m. The restricted reorientation of this small dipole component occurs by rotation about an axis perpendicular to the molecular length and requires the large activation enthalpy of (120 ± 20) kJ mol–1. The value found for the high frequency permittivity shows the presence of a second absorption at higher frequencies. The lower frequency absorption now reported could not be detected in the isotropic phase.