Categories, Processability, Applications and Research Advances in Liquid Crystalline Polymer
YIN Weifeng, ZENG Yaode, YANG Zhongqiang, ZHANG Jiming, LIU Rui, HUO Cui, YAN Shanyin
The Sub-centers of National Engineering Research Center of Electronic Circuits Base Materials,Shaanxi Shengyi Technology Co., Ltd., Xianyang 712000, Shaanxi, China
Abstract: Liquid crystal polymer (LCP) is divided into lyotropic LCP and thermotropic LCP. It exists in a liquid crystal phase under certain conditions with a unique molecular orientation. LCP combines the polymer and liquid crystal characteristics with excellent mechanical, dielectric, and optical properties. The LCP normally exhibit good thermal stability, high modulus, low melt viscosity, very small thermal expansion coefficient, low dielectric loss, and high strength. LCP has applications widely at the area of high-frequency and high-speed electronic communications, biomedi-cal polymer, LCP composites and so on. LCP has attracted much more interest because of poor molding processability compared with general plastic polymers such as polyethylene and polypropylene. This urges intensive research endeavors to study the influence of factors on molding processability, such as filling filler, processing temperature, theoretical models, interface compatibility, and so on. And the influence on mechanical property of LCP fibre is also studied, such as heating parameters, stretching ratio, et al. Meanwhile, there also attracted much more attention on the influence of LCP’s application, such as the influence of PCB processing and surface treatment on data transmission, the influence of processing conditions and self-reinforced in-situ capabilities on LCP composite properties, and the influence of feasibility on applications at the field of biomedicine, optics, memory materials, thermal conductivity, etc. Research results show that the properties of LCP extruded products, such as mechanical modulus, resistivity and compatibility, was significantly improved by LCP content, stretching ratio, melt viscosity, processing temperature, and inorganic filler content. And the mechanical properties of LCP composites was significantly improved by reinforcing material type, melt viscosity, LCP content, etc. The LCP antenna performance is excellent with high-bandwidth and highly reliable connectivity due to dielectric loss factor less than 0.0048 at 30—110 GHz. And the LCP antenna has excellent performances, such as wide bandwidth and efficient connection, by further optimizing the PCB processing parameters and surface treatment of LCP. LCP also has application in the field of biomedicine, such as antigen detection, sensors, effective component for neural networks. And in the field of polymer composites, the mechanical properties of LCP composites was greatly improved with the optimization of processing parameters. Additionally, LCP was also explored in field of memory, optics, and heat conduction. This article gives a review on the molding processability, including extrusion, injection, and spinning processability. The LCP categories, application progress and research efforts are mentioned. In addition, the prospect of LCP is also presented.