Influence of ionic impurities on the dielectric properties of lignin

Abstract

Lignin is one of the most common biopolymers. The application of the electrophysical properties of the polymer is one of the directions of its use. The effect of impurities potassium bromide with an ionic crystal lattice on the electrophysical properties of lignin has been shown. The study of the frequency dependences of the specific electrical conductivity and the components of the complex dielectric permittivity in the frequency range from 6 × 10−2 to 6 × 107 rad s−1 was carried out. The nonadditivity of the electrophysical properties of the lignin‐potassium bromide system has been shown. It is established that the relaxation time of the π‐electrons of the aromatic rings of lignin depends on the content of potassium bromide in the mixture and varies from 1.6 × 10−7 (100% lignin) to 7.5 × 10−4 s (1% of KBr in mixture). The orientation of the positive charge of potassium atom of the KBr dipole atom to the π‐electrons of the benzene ring of lignin leads to change of high‐frequency relaxation time. This effect can be used in frequency filter to eliminate electronic polarization in the high‐frequency region. Thus, the polarization of ionic impurities has a significant effect on the dielectric properties of lignin in the region of medium and high frequencies of alternating electric field.