液晶聚合物的开发与研究进展

液晶聚合物是近年开发的一类新型高性能材料。本文介绍了液晶聚合物的研究和发展状况，着重论述了新型液晶聚合物的开发、液晶聚合物的增强和填充、液晶聚合物合金以及分子复合材料等最新进展，并探讨了液晶聚合物的特性及其在宇航、电子、通讯等高技术领域中的应用前景。     

高分子液晶的应用

<正> 在本篇的第一部分“高分子液晶的发展”中已经介绍了高分子液晶的物性、分类和分子结构等,这一部分将介绍液晶材料的制备、工业化现状及应用。一、液晶聚合物的合成及成型液晶聚合物的制备可采用通常缩聚反应方法,如熔融缩聚、溶液缩聚、界面缩聚以及     

特种工程塑料聚醚砜

本文综述了特种工程塑料聚醚砜的应用、发展情况；介绍其综合性能；讨论其微观结构、相态；对液晶聚合物作简要介绍，并对利用液晶聚合物诱导聚醚砜结晶以达到改性目的的可行性进行了讨论。     

液晶聚合物(LCP)发展概况

液晶聚合物是一个很时兴的课题。这个材料好的力学性质激发了研究兴趣。它们具有理论和实际应用的重要性。在过去的十多年里取得了飞速的发展。在这篇文章里我们将介绍一些液晶聚合物的基本知识,如一般的概念、发展里程碑、分子学基础、结构、流变和性质等等。但是我们把重点主要放在高效用液晶聚合物和普通塑料材料的结构差别上,为的是让人们更好地了解这个新的液晶聚合物材料。同时对小分子液晶特征和液晶显示也做了介绍。     

高性能工程塑料——液晶聚合物

介绍了液晶聚合物作为优异工程塑料的发展概况,叙述了热致性液晶聚合物的优异性能、合成及加工方法,提出了热致性液晶聚合物可通过与填料、纤维掺混或分子工程得到自身增强。并叙述了近年来国外开发热致性液晶聚合物新品种的方向。     

液晶聚合物的注射成型技术

叙述了特种工程塑料液晶聚合物的结构、性能特点及应用；介绍了液晶聚合物制品和模具的设计应考虑的因素；重点阐述了液晶聚合物制品的注射成型工艺，包括原料干燥、料筒温度、注射压力和速度、嵌件预热模具温度、成型周期和注意事项。     

热致性液晶聚合物改性环氧树脂的研究进展

本文介绍了热致性液晶聚合物的结构、性能及其应用,在理论上阐述了热致性液晶聚合物改型环氧树脂的机理,介绍了国内热致性液晶聚合物改性环氧树脂的研究进展。     

液晶聚合物的结构及其发展

亲液性液晶聚合物的发展刺激着热致性液晶聚合物的发展。两者的区别在于后者能熔融模塑成纤维和薄膜。根据液晶聚合物的结构,可分为主链型和支链型两类。随着刚性链段的增长,液晶聚合物的相转变温度、耐热性和机械性等将提高。最近,热致性液晶聚合物在迅速发展中。尤以Dartco Manufacturing Inc.取得的进展最为显著。称为Xydar的液晶聚合物是由双苯酚、对羟基苯甲酸和对苯二甲酸制得,其为可以注射成型的第一种液晶聚合物,从而在高温塑料领域里树立了重要的里程碑。     

液晶高分子及其应用

液晶高分子是一类较新的高分子材料,是一类大规模研究工作起步较晚的液晶材料,但由于其本身无与伦比的优点,以及与信息技术、新材料和生命科学相互促进作用,已成为世纪之交的热点之一。简要介绍了液晶高分子聚合物的类型、特性、主要应用以及液晶高分子设计的前景。     

化纤概况

971001高性能纤维Wardl,M,…;Advanees in Fibre Seienee,1992,P.1十(英)介绍了关于从易溶的液晶聚合物或拉伸柔性聚合物至很高的拉神比制取高模量高强度纤维的决定性因素,也包括其潜在性质和结构方面的内容。一份描绘从高固有刚性和强度的刚性链液晶聚合物到柔性链聚合物发展高性能聚合物纤维的略图强调,为改善拉伸性质,需要特殊的加工条件,并综述了最近关于聚合物纤维结构的研究和结构对于提高拉伸性能的关系。概述了最近发展的高性能纤维,聚乙烯纤维,包括高模量熔纺纤维,高模量高强度凝胶纺纤维及性质;液晶聚合物纤维;包括易溶的液晶…     

Advanced injection molding mold and molding process for improvement of weld line strengths and isotropy of glass fiber filled aromatic polyester LCP

An advanced injection molding tool for measurement of mechanical strength and anisotropy of liquid crystal polymers (LCP)/mineral filler composites was developed. The mold produces thin‐walled LCP specimens that can be used by water cutting technique for production of an injection molded flow direction test bar, a transverse‐to‐injection molded flow direction test bar, a test bar for knit line strength measurement, and a test bar for butt weld line strength measurement. This tool and its use for molding experiments were optimized by experimental research and by computational calculations based on experimental parameters obtained by molding of several LCP test materials. Different pressure profiles and different injection speeds were tested as well as application of mold overflow phenomenon in production of test specimens. It was observed that a pressure controlled X‐melt technique and on the other hand fast injection speeds with overflow in conventional molding methods gave the best strength and isotropy properties for the test specimens. Results indicate that the mold developed is useful for determination of anisotropic and weld line strength properties of LCP composites. When developing “isotropic LCP” by different possibilities of nanotechnology this tool significantly reduces time of LCP material and process development. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Flow behaviour and microstructure evolution in novel SiO2/PP/LCP ternary composites: effects of filler properties and mixing sequence

When silica (SiO₂) fillers were introduced into the polypropylene (PP) and liquid‐crystalline polymer (LCP) blend, it was found that the mixing sequence, the filler size, and the filler surface nature affected the rheology of the composites and the morphology of the LCP phase in the ternary composite. In particular, the compatibility between the filler and the PP matrix was found to exert a strong influence on the droplet‐fibril transition. The incorporation of the hydrophobic silica to the LCP/PP blend facilitated the fibrillation of LCP because the hydrophobic filler demonstrated affinity towards the hydrophobic PP matrix. The preferential residence of the hydrophobic silica in the PP phase would minimise the LCP domain disruption leading to the formation of LCP fibrils with high aspect ratios. The use of fine filler and in situ blending, which promoted the filler–LCP interaction, could prevent coalescence, inhibit deformation and hinder fibril development as well. © 2003 Society of Chemical Industry     

液晶聚合物成型技术探讨

介绍液晶聚合物(LCP)的工艺特性，指出注射模设计的要点和注塑机选用的要求，阐述成型中料筒温度、模具温度、注塑压力、注射速率和时间等工艺参数确定的原则。并详细介绍几种典型LCP材料注射成型工艺、成型加工要点和注意事项。     

1994—1995年我国塑料工业进展

介绍了1994～1995年我国塑料工业进展.依据1994年7月～1995年6月国内有关合成树脂和塑料工业的文献资料,对通用热塑性树脂(包括聚乙烯、聚丙烯、聚氯乙烯、聚苯乙烯及ABS)、热固性树脂(包括环氧树脂、酚醛树脂、聚氨酯和不饱和聚酯)、工程塑料(包括尼龙、聚碳酸酯、聚甲醛、热塑性聚酯)、特种工程塑料(包括聚苯硫醚、液晶聚合物、聚醚醚酮和聚醚砜)以及有机硅树脂、有机氟树脂的产量和消费、合成工艺、树脂品种延伸、产品应用开发等进展进行了详尽的介绍.且对塑料成型加工与设备、塑料助剂、塑料的分析测试及应用领域方面的进展进行了总结.     

液晶高分子分子设计及合成方法的研究进展

综述了液晶高分子(LCP)分子设计的一般原则及其合成方法。着重介绍了热致主链型LCP、溶致主链型LCP及侧链LCP的分子设计与合成技术,并列举了国内外各种类型LCP的合成研究先例。     

A study of critical processing technologies of liquid crystal polymer printed circuit board for high speed application

Recent demand for high‐frequency and high‐speed signal transmission over GHz is driving the printed circuit board (PCB) industry towards a more advanced material‐based era. To meet this market demand, liquid crystal polymer (LCP) has been suggested for its predominant material characteristics, such as high temperature resistance, low moisture absorption and excellent dimensional stability. However, former experimental and theoretical studies on the fabrication technology for processing the LCP PCB at different treatment conditions are lacking. This article thus evaluates the recent development of LCP PCB process technology. Different process approaches involving in lamination, drilling, desmearing, and metallization are proposed and compared, and associated reliability testing is addressed. Experimental results are shown to demonstrate the efficacy of the proposed approach for developing the process technology of LCP PCB. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

液晶聚合物分子设计研究进展

综述了液晶聚合(物LCP)分子设计的一般原则,着重介绍了主链型热致LCP、主链型溶致LCP及侧链LCP的分子结构和分子设计并,列举了国内外各类型LCP的分子设计实例。     

Electrorheological effect of liquid crystalline polymers

Large increases in shear stress upon application of a 2.0 kV/mm electric field were observed in homogeneous fluids composed of polysiloxane-based liquid crystalline polymers (LCPs) in dimethyl silicone at a shear rate of 200 s^?1. The increase was largest (about 3,000 Pa at 50°C) with LCP consisting of a polysiloxane bearing mesogenic groups as side chains. With LCP having the mesogenic groups within the main chain, the maximum increase was about 1,300 Pa at 90°C. It was about 400 Pa at 30°C with LCP having the mesogenic groups at both ends only (biterminal), and several Pa at 30°C with LCP having the mesogenic group at one end only (monoterminal). The increases were smaller with mesogenic groups of lower positive dielectric anisotropy in the side chain LCP. The side chain, biterminal, and monoterminal LCPs exhibited Newtonian flow in the electric field and shear stress yield at low shear rates in its absence. The complex dynamic modulus and viscosity of the side chain LCP in the electric field showed no dependence on strain at deformation displacements approaching 5°, but in its absence were generally strain-dependent, and suggest the strong electrorheological effect of these homogeneous LCP fluids is related to a flexible-chain linkage between their crystalline domains. © 1995 John Wiley & Sons, Inc.     

Novel approach to fibrillation of LCP in an LCP/PP blend

A novel concept of improving shear‐induced fibrillation of liquid crystalline polymer (LCP) in LCP/thermoplastic blend systems was introduced. Silica fillers (SiO₂) were added to an LCP/polypropylene (PP) system to serve as a viscosity thickening agent and to improve the fibrillation of the LCP phase. The formation of LCP fibrils was found to enhance with the incorporation of 5–15 wt % of fillers. The presence of LCP fibrils improved the flow properties of the LCP/PP/SiO₂ composites. It was evident from the rheological and morphological studies that the addition of silica led to an increase of the aspect ratio of the LCP fibrils, which, in turn, should improve their effectiveness as reinforcements and/or toughening agents. Substantial improvement in LCP aspect ratio was achieved by the introduction of hydrophobic SiO₂ fillers in the PP/LCP blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2070–2078, 2002