液晶聚合物技术进展

1 原料开发 目前用作液晶聚合物原料的有对羟基苯甲酸、2—羟基—6—萘甲酸,4,4’一二羟基—1,1’—联苯酚、对苯二酚等。但是由于生产企业少、生产规模小,因此价格高,也使液晶聚合物(LCP)价格难以降低。随着LCP市场规模的扩大,从市场经济角度来看,价格问题相当关键,这也促进了对LCP原料及其制造技术的开发。     

液晶聚合物综述

固体结晶是三维有序的,液体是无序的,液晶则介乎二者之间。近年来开发的液晶聚合物,在工业上和学术上引起了很大的兴趣。 聚合物在液体时,不是溶液就是熔融物,而液晶聚合物介乎固体结晶和各向同性液体之间。这种物态不符合真正固体或真正液体的准则,而是具有相似于固体 液体的特性。例如,     

热致性液晶聚合物合金的性能与加工

介绍热致性液晶聚合物金的类型，性能，加工及发展前景。     

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。     

液晶芳香族聚苯唑纤维的性能

论述了液晶态芳香族聚苯唑的干喷湿纺纤维的纺丝工艺条件、热处理条件等对其力学性能的影响,并提出了几种有效的改善其抗压力学性能的途径,指出多数芳香族聚苯唑纤维的抗张强度高于３．１ＧＰａ,抗张模量高于２００ＧＰａ,其中以聚对苯撑苯并二唑纤维性能最佳,其最高抗张强度和抗张模量分别可达６．９ＧＰａ和     

热致液晶聚合物原位增强复合材料的研究

本文对热致液晶聚合物及其原位复合材料的研究进展和前沿问题作了详细评述。     

热致性液晶聚合物的新进展

一、前言热致性液晶聚合物(TLCP)是当前最热门的研究和开发领域。自从DartcoManufacturing Inc发表了Xydar以来,在工程塑料中TLCP犹如雨后春笋在蓬勃发展,迄至现在,世界上已有30多家公司进行了TLCP的开发。 TLCP不仅具有优良的性能、广泛的用途,而且在高技术领域里也是正在发展的新型材料。     

液晶聚合物

液晶聚合物简称LCP,由刚性的杆形有序分子构成,这些分子即使在熔化时也保持晶态次序。按照分子的定向情况,液晶聚合物可分为向列相型(晶体定向相同但次序却是任意的)和层列相型(晶体定向相同并在不同的层次上)两种,其中向列相型的液晶聚合物作为高性能的热塑性材料的潜力非常     

热致液晶性聚合物的序态结构及其相变行为

本文介绍用透射电子显微镜（ＴＥＭ）、光学显微镜（ＯＭ）、热台Ｘ射线衍射（ＨＸＲＤ）等方法研究组成不同全芳香族热致液晶聚合物的序态结构和液晶行为。研究结果表明，它们在序态结构、相变热效应以及衍射强度随温度的变化规律等方面存在明显差异。并证明这种差异不仅取决于材料的组成，而且在一定条件下取决于晶体发育程度和其本身的致密性。     

芳杂环聚合物热结构化过程研究

用原位Ｘ射线衍射技术跟踪考察３种杂环聚合物热结构化过程。从Ｘ射线衍射动态谱发现,试样单元结构的分子链在６００℃以前遭致破坏,使得分子的排列呈无序状态,继续升高温度其分子逐渐变成环环六方网面和堆积成类石墨片状结构,而试样Ⅱ还呈现出反射面存在的结构特征。     

两相顺流纤维液膜间传质的分析

介绍了一种新型两相顺流介质在纤维丝上形成液膜 ,实现膜面接触传质的原理。运用数值模拟方法分析 ,得出两相顺流液膜间形成层流时的流速比及其与传质效率的关系     

滑石粉/聚丙烯复合材料的制备及结晶性能研究进展

综述了Talc/PP复合材料的制备方法,提高滑石粉与聚丙烯相容性的方法,以及滑石粉/聚丙烯复合材料结晶性能的研究进展。     

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。     

Binary Blends of Polytetrafluoroethylene and Liquid Crystalline Polymer

Blends of polytetrafluoroethylene (PTFE) and liquid crystalline polymer (LCP) were prepared by varying the amount of LCP when using a melt mixing technique. The rheological, morphological, thermal, and dynamic mechanical properties of the blends were investigated. The viscosity of the blends was decreased with the increasing LCP content in the blends up to 20% of LCP. With further loadings of LCP a slight improvement in viscosity was observed. This decrease in the viscosity was attributed to be the interlayer slip of the polymers due to formation of the elongated fibrils of LCP, whereas at higher amounts of LCP the fibril nature of LCP was not apparent, which is revealed by the scanning electron microscopic study. The differential scanning calorimetry (DSC) results showed a shift in the melting temperature (T_m) of PTFE with the addition of LCP. This shift in the T_m of PTFE is due to increasing crystallinity. This is further supported by the X-ray diffraction (XRD) and dynamic mechanical analysis (DMA) studies.     

芳香酯类液晶高分子的研究进展

液晶高分子在结构材料和功能材料方面被称为一类全新的高性能材料，而酯类液晶高分子作为液晶领域发展最为成熟的一个行业，已经取得了巨大的成就，其合成方法与性能研究也日臻完善。本文主要对酯类液晶的合成及其性能进行了归纳和评述，其主要侧重不饱和键、联苯、偶氮、胆甾醇及二茂铁等类型酯类液晶，并将一些具有特殊功能的酯类液晶也进行了简要的介绍，最后得出：酯类液晶的合成方法简单、产率较高且大都具有液晶性。文章最后简要概述了其应用前景。     

Inorganic Layers on Polymeric Films – Influence of Defects and Morphology on Barrier Properties

Flexible polymeric films are not only widely used in conventional packaging as substitute for glass and aluminum foil packaging but are also proposed as encapsulation for novel products, like flexible solar cells or organic light‐emitting devices. The two essential properties of the polymeric packaging are flexibility and good permeation barrier properties against gases and vapors. This article deals with vacuum web coating as a common way of increasing barrier properties of polymeric films and the problems related to this procedure. Defects caused by particles and surface imperfections are found to dominate the permeation rate for such coated polymeric films. Atomic force microscopy, electron and also optical microscopy was used for analysis of the coating layer. Three‐dimensional numerical simulations were performed for modeling of the influence of defect size, spacing and film thickness. Results of numerical modeling and of many practical experiments show that the permeability is almost independent of the substrate film thickness when a critical thickness is exceeded. In most cases the defects can be treated as independent of each other. The gas permeability of vacuum web‐coated polymeric films can be quantitatively predicted by a simple formula. For gases, like oxygen, it is shown that a statistic analysis of the defect sizes by optical microscopy is sufficient. For water vapor transmission, however, the structure of the coating layer itself has also to be taken into account.     

Stability Behavior of Liquid Jets under Gravity

The influence of gravity on the stability behavior of falling liquid strands without external excitation was investigated. To this end, a mathematic‐physical model was developed for the analysis of the stability behavior of liquid strands in the range of low to higher viscosity, the main emphasis being on gravity. The characteristics of the model are discussed and, finally, the stability criterion is derived for the quantitative determination of the point of disintegration.     

Crystallinity measurements of polyamides adsorbed as thin films

The crystallinity degree of thin polyamide films (PA66, 610 and 612) spin coated on four types of substrates are estimated. Two original methods based on the analysis of infrared spectra are proposed. The high sensitivity of polarization modulation reflection-absorption spectroscopy for the study of thin polymer films leads to quantitative results. These two methods offer the possibility to estimate the degree of crystallinity by using infrared spectroscopy, independently of any other technique, if the crystallinity degree in the isotropic bulk state is known. Polyamides are spin coated, on the one hand, on inert and highly reflecting gold substrates, and on the other hand, on the same gold substrates grafted with different chemical functionality. Our calculations show a lower crystallinity degree for inert substrate and higher values for functionalized systems with respect to the bulk. These results suggest that the surface chemical grafts not only play the role of nucleation seeds, but also affect the crystalline morphology as seen by atomic force microscopy.