液晶环氧树脂研究进展

介绍了液晶环氧单体的结构,液晶环氧化合物(LCE)的合成和固化,综述了国内外液晶环氧树脂的研究进展,分析了液晶环氧树脂研究和应用中存在的问题,并展望了今后液晶环氧树脂材料的发展方向。     

环氧树脂的改性研究发展

概述了近年来利用互穿网络法、液晶增韧法、纳米粒子增韧等改性环氧树脂的新方法、新途径。其中包括丙烯酸 /环氧 ,聚氨酯 /环氧 ,双马来酰亚胺 /环氧 ,聚酰胺酸 /环氧IPN结构 ,热致液晶环氧 (TCLP) ,4,4’ -二缩水甘油醚二苯基酰氧 (PHBHQ) ,侧链液晶环氧 (LCGMB) ;nmSiO2 /epoxy ,nm粘土 /环氧体系等。     

联苯类液晶环氧树脂的合成研究

采用二步法合成液晶环氧树脂,首先合成含有刚性棒状介晶基元的联苯类环氧预聚体,将介晶基团通过共价键接入环氧树脂网络,再通过固化反应得到高度交联的液晶热固性树脂.探讨了固化剂及碱的用量、反应温度等对合成液晶的影响,利用IR与DSC等分析手段对合成的单官能团液晶环氧化合物（SCEP）和液晶环氧树脂进行结构表征,结果表明合成的物质为低分子液晶环氧化合物.     

液晶环氧/二元胺/CYD-128体系固化行为的研究——Ⅱ性能及增韧机理

采用液晶环氧 (PHBHQ)增韧环氧CYD - 12 8,研究了液晶含量对浇铸体耐热性、冲击强度、弯曲强度的影响。结果表明 ,随液晶含量的增加 ,凝胶时间逐渐缩短 ;当液晶含量为 5 0 %时 ,冲击强度为 40 1kJ/m2比不加液晶环氧时CYD - 12 8体系 (2 3kJ/m2 )提高了近 0 7倍 ,热变形温度提高近 30℃。结合DMTA图和SEM照片 ,分析了液晶环氧增韧的机理。PHBHQ/CYD - 12 8/固化剂体系是部分相容体系 ,在成型过程中发生相分离 ,PHBHQ能形成介晶域 ,起增强和诱发银纹和剪切带的作用 ,从而吸收大量的能量 ,使环氧的韧性得以大幅度地提高     

侧链液晶环氧树脂及其固化物的研究

本文以联苯单酚为介晶基元合成了单官能团环氧树脂，再与双酚A型环氧树脂和二元胺交联聚合制备了侧链型的液晶环氧网络材料，保持了较好的液晶织态。     

环氧灌封材料的研究进展

介绍了电子产品环氧灌封材料的两种灌封工艺；常态灌封和真空灌封；针对环氧树脂本身脆性大的缺点，详述了环氧灌封材料的增韧方法，主要包括端羧基聚丁二烯-丙烯腈(CTBN)增韧、复合弹性体微粒增韧、液晶环氧增韧、氰酸酯树脂增韧和纳米粒子增韧，同时对其增韧效果进行了评价；最后列举了三种典型环氧灌封材料的应用配方和它们的性能指标。     

含环氧键的液晶高分子改性环氧树脂的研究

利用自制的含有环氧键的液晶高分子对环氧树脂/芳香胺固化体系进行改性,对改性样品进行了测试.对比改性前后环氧树脂性能,发现含环氧键的液晶高分子能显著提高环氧树脂的韧性,并对环氧树脂的耐热性也有较大程度的改善.采用SEM分析了改性环氧树脂体系的断面结构.     

双酚-S酯液晶环氧树脂的的合成与表征

以乙二醇单烯丙基醚（AHEE）、对羟基苯甲酸乙酯和双酚-S（BPS）为原料,经酯化和氧化的方法合成了4,4’-二[4-（2,3-环氧丙氧基乙氧基）]苯甲酸双酚-S酯（p—BPSDEB）环氧液晶化合物,用FTIRR、^1H NMR、DSC和偏光显微镜对液晶化合物进行了表征。证明该化合物为近晶型液晶,其熔点是106℃。     

液晶聚合物在涂料中的应用

液晶聚合物是具有分子部分取向状态的聚合物，分子沿流动方向的聚向导致其粘度较低，从而使之适用于高固体分涂料，这类聚合物还显示优良的硬度和柔韧性的平衡，评述了如丙烯酸、醇酸、聚酯和环氧等各类树脂的合成方法及其表征的不同技术，讨论了液晶聚合物超过其对应无定形聚合的优点，给出了配制烘烤型和非烘烤型液晶丙烯酸共聚物的原则。     

芳香酯基液晶环氧树脂的合成

以对羟基苯甲酸和对苯二酚为原料,用对甲苯磺酸共沸催化法合成对羟基苯甲酸对苯二酚酯;再由对羟基苯甲酸对苯二酚酯与4-溴环氧丁烷进行反应合成酚酯型液晶环氧物质4-(2-(环氧乙烷基)乙氧基)苯甲酸-4-(2-(环氧乙烷基)乙氧基)苯酚酯。研究该化合物与4,4’-二氨基二苯甲烷(DDM)固化反应的固化特性及固化物的力学性能,并对其结构以及固化行为和固化物的形态进行了表征。结果表明该液晶环氧树脂与DDM交联聚合的网络保持了较好的液晶织态,聚合物具有较好的综合性能。     

The effect of stoichiometry on the fracture toughness of a liquid crystalline epoxy

The fracture toughness of a liquid crystalline epoxy was compared with that of a standard bisphenol‐A based epoxy to understand how both the liquid crystalline structure and the crosslink density affect fracture toughness. For the liquid crystalline epoxy, the liquid crystalline domain size decreased with increasing temperature of cure and away from the stoichiometric formulation. Quantitative fractography showed that there is a competition between the liquid crystalline domain structure and the stoichiometry in determining the fracture toughness. At some cure conditions the effect of the domains is dominant. When the cure conditions are adjusted to reduce the domain size, the domains become too small to affect the fracture toughness, and thus the effect of the stoichiometry is dominant. The result is that the formation of liquid crystalline structure only increases the fracture toughness relative to that of a traditional epoxy at and near the stoichiometric formulation.     

Synthesis and thermal properties of combined liquid crystalline epoxy resins

Liquid crystalline epoxy resins were prepared by the curing reaction of epoxy and amine compounds with a mesogenic group in the mesomorphic temperature range. Some epoxy resins exhibited a typical liquid crystalline phase. Curing reaction of a mesogenic epoxy compound with an aliphatic amine compound containing cyano biphenyl group was faster than that of another epoxy resins confirmed by thermally controlled Fourier transform infrared measurements. The glass transition temperature of the liquid crystalline epoxy resin containing cyano biphenyl group increased with increasing curing reaction time. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1979–1990, 1998     

Liquid crystalline epoxy resin based on biphenyl mesogen: Effect of magnetic field orientation during cure

A biphenyl based epoxy monomer, 4,4′-diglycidyloxybiphenyl (BP), was synthesized and cured with a tetra-functional amine, sulfanilamide (SAA), to obtain a liquid crystalline epoxy network. The curing behavior of BP with SAA was studied using differential scanning calorimetry, polarized optical microscopy, and parallel plate rheology. Macroscopic orientation of the liquid crystalline epoxy resins (LCERs) was achieved by curing in a high strength magnetic field, and quantified by an orientation parameter determined with wide angle X-ray diffraction. The effects of orientation on the glass transition temperature, coefficient of thermal expansion, and dynamic mechanical properties of the LCERs were investigated. The results reveal that the formation of the liquid crystalline phase has a dramatic influence on the curing reaction, leading to a decrease in viscosity of the reacting system. Oriented LCERs exhibit anisotropic thermal expansion behavior and significant improvements of thermomechanical properties.     

Liquid crystalline epoxy based thermosetting polymers

In recent years many examples of liquid crystalline thermosetting polymers have been reported in the literature. The main reason for the development of this new class of materials comes from both technological and theoretical implications. Among the different anisotropic thermosets, epoxy resins represent a family of polymers whose properties make them primary candidates in different fields ranging from high performance matrices in advanced composites to polymers for optical applications. The chemistry of curing process of amine hardened conventional epoxy resins is well known from the literature; however some substantial differences arise during liquid crystalline epoxy monomers crosslinking. The level of order of the cured resin can be strongly affected by the nature of the hardener, as well as the physical properties of the cured material. This review will present the results of synthesis and physico-chemical characterization of liquid crystalline epoxy resins in relation to their applications in some specific fields.     

环氧树脂增韧技术研究进展及发展方向

本文回顾了环氧树脂增韧改性的常用方法，详细介绍了橡胶类弹性体、热塑性树脂、热致性液晶聚合物、刚性粒子等环氧树脂的增韧改性方法及其增韧机理，并列举了最新研究情况。还对环氧树脂改性的发展方向进行了展望。     

新型液晶环氧树脂及其共聚物

介绍了联苯型液晶环氧树脂脂的合成及其与双马来酰亚胺树脂的共聚物。应用红外光谱、ＤＳＣ、热台偏光显微镜对环氧树脂和共聚物的液晶行为进行了表征。经对固化行为研究，得到了共聚物固化反应的活化能和凝胶化的数学模型。     

电子封装材料用环氧树脂增韧研究进展

未改性环氧树脂固化物存在质脆、冲击性能差等缺点，限制了它在复杂环境下的应用。针对这些不足，国内外科研工作者对其进行了大量改性研究。文中综述了近年来相关研究领域的研究进展及发展趋势。