Dielectric properties of three liquid crystal polymers

Abstract

Dielectric properties of three kinds of liquid crystal polymers (LCPs) were investigated by measuring their thermal properties, thermally stimulated polarization and depolarization currents, and complex dielectric permittivity. To make clear the differences among the three LCP samples, complex electric modulus was introduced, which was found to be effective to suppress the effects of large conduction currents at high temperatures. Moreover, the slopes of the frequency dependence of ε r ' and ε r " are different below and above the phase transition temperature, indicating that the accumulation of charges occurs in front of the electrodes. The experimental results indicate that the phase transition has a significant influence on both the electrical conduction and dielectric relaxation for all LCPs.

Effect of Fluorinated Substituents on Solubility and Dielectric Properties of the Liquid Crystalline Poly(ester imides)

“…The powders melt after T m during heating without any birefringence. The sp hybridization of the central carbon of BPAF destroys the LC phase of the resulting copolymers. The maximum mole percent of this bisphenol that can be incorporated into the LC polyesters based on chlorohydroquinone and terephthalic acid without completely destroying their LC phases has been reported …”

“…1,2 A liquid crystalline all aromatic polyester is regarded as a promising substrate material for the flexible copper clad laminate (FCCL) applied in 5G communication attributed to its prominent properties. 3 The film named Kuraray's Vecstar CTZ exhibits moderate D k of 3.33 and low D f of 0.0028 at 10 GHz. 4 However, it is difficult for it to be processed into films, because the LCP resin is insoluble in common organic solvents.…”

“…With the thriving progression of 5G communication technologies, the transmission rate, integrity, and distortion of the signals become important. Therefore, much attention has been paid on polymers with low dielectric constant ( D k ) and low dielectric loss ( D f ) at high frequency (≥10 GHz). , A liquid crystalline all aromatic polyester is regarded as a promising substrate material for the flexible copper clad laminate (FCCL) applied in 5G communication attributed to its prominent properties . The film named Kuraray’s Vecstar CTZ exhibits moderate D k of 3.33 and low D f of 0.0028 at 10 GHz .…”