Dielectric Relaxation Properties and Alignment Behavior of Liquid-Crystalline Side-Chain Polymers,
Abstract
We describe the alignment behaviour of different liquid crystalline (LC) side-chain polymers when they are subjected to electrical/thermal treatments. It is shown that the alignment behaviour is determined by several variables for a given polymer, including the amplitude and frequency of the applied electric field and both the thermal and electrical history of the sample and its low-field dielectric relaxation properties. It is shown that the dielectric relaxation spectra vary systematically with the degree of macroscopic alignment of the sample and its temperature. The anisotropy of dielectric properties may be understood in terms of the anisotropic reorientational motions of the dipolar mesogenic groups. The permittivity data allow the degree of macroscopic alignment to be determined, via a director order parameter Sd for samples prepared in different ways and also for samples being realigned, as a function of time, by directing electric fields. We illustrate these principles through data we have obtained for a copolymer having the mesogenic groups attached longitudinally and transversely to the main chain.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1991
- Accession Number
- ADP007476
Entities
People
- Ali Nazemi
- Graham Williams
Organizations
- Swansea University