Different molecular mechanisms for the dielectric hysteresis and pyroelectricity in a poly(vinyl alcohol) with azobenzene-alkoxy side chains

摘要

By means of pyroelectrical measurements and dielectric spectroscopy as well as structural information from differential scanning calorimetry, it is shown that, in a poly(vinyl alcohol) with azobenzene-alkoxy side chains, pyroelectricity and dielectric hysteresis which are usually related to each other have different origins. The pyroelectric effect is explained with reversible dipole- density changes upon thermal expansion, whereas the dielectric hysteresis is proposed to result from a charge- carrier polarization.