Papers by Keyword: Liquid Crystal Polymer

Abstract: Liquid crystal (LC) polymer, composited with inorganic filler, has a broad application prospect in electronic and electrical industry. In this research, permittivity (ε_r) and dielectric loss tangent (tanδ) of LC composites under different temperatures and frequencies were investigated, and activation energies were calculated and analyzed. At low temperatures and high frequencies, LC composites exhibited well dielectric properties. ε_r changed a little (3.6~4.0) in temperature range of-60°C~160°C when frequency was higher than 10Hz, but increased sharply when temperatures was higher than 100°C and frequency was lower 10Hz. The tanδ increased sharply with increasing temperature when temperatures was higher than 100°C and frequency was lower than 10²Hz, and when frequency was above 10²Hz, the value of tanδ changed gently (10^-3~10^-2). The peak of tanδ would translate to higher frequencies direction with increasing temperature in tanδ-frequency curve, and to higher temperatures direction with increasing frequency in tanδ-temperature curve. Activation energy is calculated by fitting the peak of the imaginary of the electric modulus, and activation energy is 0.43eV in low temperature and 1.59eV in high temperature.

Abstract: In order to broaden the application range of LCP, the simulation of the LCP Hele-Shaw flow in the square cavity was conducted. The temperature of the cavity was constant 300°C. In the simulation the Leslie-Ericksen and TIF theories were used. With this simulation results, we can predict the position of the flow front at any time during the whole injection process and grasp the change of the pressure field and the velocity field. The change of the pressure and the velocity fields were very slow, there was no distortion point in the whole flow field. In the layer near the wall, the directors arranged evenly according to the direction of the flow and in the center layer it was decided by the shear rate in the X-Y plane.