Structural Regulation of Microcellular Thermotropic Liquid Crystalline Polymer with Low‐Dielectric Properties During Supercritical Fluid Foaming Process

With the development of radio technology, 5G electronic equipment has higher requirements for materials. This has become an imperative matter to realize the controllable preparation of Thermotropic liquid crystal polyester (TLCP) foams with homogeneous microcellular. Accordingly, the foaming behavior of TLCP in isotropic state is investigated. TLCP foams are prepared by a one‐step rapid depressurization foaming method at different temperature pressures, with cell diameter in the range of 67.5–283.9 μm and the material density in the range of 0.37–0.25 g/cm 3 . In order to broaden the distribution of cell diameter and the density of TLCP foams, the mixture foaming agent of N 2 and CO 2 is used in foaming process. When mixture foaming agents are used, the cell diameter is widened to the range of 40.5–283.9 μm, and the material density is widened to the range of 0.70–0.25 g/cm3, which realizes the controllable preparation of cell diameter and material density of TLCP. The dielectric constant and dielectric loss of TLCP foams can be as low as 1.35‰ and 0.85‰ at 10 GHz, respectively. The structural regulation of low‐dielectric TLCP microcellular materials is achieved for the first time by way of varying the temperature, pressure, and co‐blowing agent ratio.