Dielectric relaxation processes observed in hydroxypropyl Cellulose − Ethanol solutions

Abstract

We performed dielectric measurements of hydroxypropyl cellulose (HPC) − ethanol solutions with various HPC concentrations at various temperatures. A symmetric primary relaxation process reflecting the motion of ethanol molecules was observed in the high-temperature range. Below 250 K, additional relaxation processes appeared on the low-frequency side of the primary process observed at high temperatures. The molecular mechanism of this separation behavior of the relaxation processes can be explained in terms of the fragmentation of the hydrogen bonding network of ethanol molecules caused by the impregnation of HPC molecules into the hydrogen bonding network of the ethanol molecules. Below 250 K, each fragment forms a larger fragment through hydrogen bonding with the HPC molecules, and the motion of these large fragments leads to an additional low-frequency relaxation process. In addition, the obtained dielectric parameters were compared with the spatial scale of the liquid crystal structure obtained by synchrotron small-angle X-ray scattering (SAXS) measurements.