Dielectric relaxation of liquid crystalline main chain polyethers

Dielectric Properties of Dual-Frequency Reactive Mesogens before and after Photopolymerization

“…The relaxation process indicated by a weak peak in ${\mathrm{normal\epsilon }}^{″}{}_{\perp }$ is attributed to β-relaxation [15,17,21]. The β-relaxation is also observed in non-liquid crystalline polymeric systems arising from rotational fluctuations of localized parts of a main chain and/or side chains attached to a main chain.…”

“…There are also few reports about electric field driven PRMs [ 13 , 14 ]. However, investigation of the dielectric properties of PRMs in these studies were not carried out adequately and the dielectric constants of RMs before polymerization were used to investigate the kinetics, although the dielectric properties of PRM, in which the fluctuations of molecules is restricted, is supposed to be different from unpolymerized RMs [ 15 – 17 ]. Therefore, investigation of relations between the dielectric property and the behavior of PRMs as actuators is necessary to achieve more development in PRM actuator research.…”

Dynamics of main-chain liquid crystalline polysiloxanes containing p-phenyleneterephthalate mesogens

“…1), the relaxation time of this process also increases ðF3H < F3Cl < F3CH 3 Þ. Several studies of liquid crystalline polymers, as well as poly(ethylene terephthalate), have reported a dielectric relaxation in the glassy state arising from motions of phenyl rings in the polymer backbone [6,24,[26][27][28][29][30]. All authors report the activation energy for this process to be on the order of 50 AE 10 kJ=mol, and s to be on the order of 10 12AE1 Hz.…”

Thermotropic Liquid Crystals of Main‐Chain Polyesters having a Mesogenic 4,4′‐Biphenyldicarboxylate Unit, 14

“…However, the LCP solid exhibits relaxation processes similar to those of conventional glassy polymers. [1][2][3][4][5][6][7][8][9] The Summary: Anisotropy in molecular motions of a glassy smectic CA (SmCA) liquid crystal of a main-chain BB-5(3-Me) polyester was examined by dynamic mechanical analysis (DMA) for fibrous monodomain samples with two distinct orientations of smectic layers perpendicular and parallel to the fiber axis. The a-process attributed to micro-Brownian motion of the polymer on the glass transition shows clear anisotropy explainable by the nature of the smectic layer structure.…”