液晶高分子聚合物的类型、加工、应用综述

Categories,Processability,Applications and Research Advances in Liquid Crystalline Polymer

液晶高分子(LCP),简单可分为溶致LCP、热致LCP,其在一定条件下以液晶相存在,有独特的分子取向,兼容高分子、液晶特性。LCP具有高耐热、高模量、低熔融粘度、极小的热膨胀系数、低介电损耗、高机械强度等优异的力学性能、介电性能、光学性能,可广泛应用于高频高速电子通讯、生物医用、复合材料等领域。与聚乙烯、聚丙烯等通用塑性聚合物相比,LCP成型工艺还不够完善,尚有许多问题亟需解决,如填料填充、加工温度、相容性等因素如何影响挤出成型产品性能,理论模型、循环加工次数、相容性等如何影响注塑成型产品性能,拉伸比、加热参数等如何影响纤维产品力学性能。此外,LCP在具体领域应用也存在较多问题,如印制电路板(PCB)加工、表面处理等如何对通信领域的信号产生影响,加工条件、自增强纤维化能力等如何对复合材料性能产生影响,以及生物医学、光学、记忆材料、导热等领域应用的可行性如何等。大量研究结果表明,LCP含量、剪切速率、加工温度、无机填料含量等因素对LCP挤出制品的模量、电阻率、相容性等有影响,增强材料类型、熔融粘度、LCP含量等因素能明显提高LCP复合材料的力学性能。通信领域,LCP在30~110 GHz的介电损耗角正切(D_(f))小于0.0048,进一步优化LCP的PCB加工参数、表面处理,制备的天线具有宽带宽、高效连接等优异性能;生物医用领域,LCP可作为抗原检测、传感器、神经网络的有效组件;复合材料领域,引入LCP、调节加工参数,可使复合材料的力学性能大幅提升。此外,LCP在记忆、光学、导热方面也有较多应用探索。本文对LCP分类进行了介绍,对LCP的挤出工艺、注塑工艺、纺丝工艺进行了说明,对LCP在通讯、生物医用、复合材料等领域进行了综述,并展望了该材料的发展前景。

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,biomedical 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.