环氧树脂增韧改性新方法

介绍了环氧树脂增韧改性的一些新方法,包括热塑性树脂增韧、互穿网络增韧、热致性液晶增韧、原位聚合增韧、核壳结构聚合物增韧等,并对其中的增韧机理作了总结分析。     

环氧树脂增韧改性的新方法

介绍了环氧树脂增韧改性的一些新方法,包括热塑性树脂增韧、互穿网络增韧、热致性液晶增韧、原位聚合增韧、核壳结构聚合物增韧等,并对其中的增韧机理作了简浅的总结分析。     

环氧树脂增韧改性研究进展

回顾了环氧树脂韧改性的一些常用方法,详细介绍了以橡胶弹性体,热塑性树脂及则性粒子增韧环氧树脂的一些重要研究情况。并且对环氧树脂增韧性性的进行了比较系统的总结,例举了一些已被人们承认的增韧机理。 还介绍了环氧树脂改性的最新方法,液晶聚合物改性,大分子固化剂增韧的一些研究情况。     

环氧树脂增韧改性研究进展

综述了增韧改性环氧树脂的方法及进展并,指出了环氧树脂增韧改性的发展方向。     

环氧树脂增韧改性技术研究进展和新方法及其机理

简单介绍了环氧树脂技术的研究进展和近期的主要应用,并概述了环氧树脂的改性技术.主要介绍了增韧改性的一些新方法,包括热塑性树脂增韧、互穿网络增韧、热致性液晶增韧、原位聚合增韧、核壳结构聚合物增韧等,主要介绍了用橡胶弹性体、热塑性树脂、刚性粒子、核壳型结构聚合物来增韧环氧树脂,以及环氧树脂绝缘性、耐湿热性和阻燃性等的改进方法,并对其中的增韧机理作了总结分析.最后本文综述了环氧树脂增韧改性技术发展及其未来展望.     

环氧树脂增韧增强改性研究进展

综述了国内环氧树脂增韧增强改性的最新研究进展,详细介绍了纳米粒子、液体橡胶、热塑性树脂、原位聚合物、液晶聚合物、核壳聚合物、大分子固化剂和膨胀型单体增韧增强环氧树脂的一些重要研究现状。对它们的增韧增强环氧树脂的优缺点和机理进行了探讨。     

橡胶增韧环氧树脂的新方法

本文讨论了液体端羧基丁腈橡胶增韧环氧树脂存在橡胶交联网络不完整问题,并进一步研究为克服此缺点而使用预制的橡胶微球(即活性微凝胶)作为环氧增韧剂的体系的表面化学性质、流变学性能、及以伯胺类固化剂固化的此体系的胶接强度及力学性能等。     

环氧树脂增韧改性研究进展

综述了环氧树脂(EP)增韧改性的主要方法,分别阐述了通过热致性液晶聚合物、纳米粒子聚合物、超支化聚合物、核壳结构聚合物、互穿网络聚合物、柔性链聚合物等方式增韧EP的原理,并分析现阶段这些技术所面临的问题,最后对其将来的发展趋势进行了展望。     

环氧树脂增韧改性的研究进展

环氧树脂(EP)具有优异的综合性能,在许多领域中都得到广泛应用。综述了EP的增韧改性研究(包括橡胶、热塑性树脂、热致液晶、互穿聚合物网络以及纳米粒子等增韧改性方法),并指出了EP增韧的主要发展趋势。     

环氧树脂增韧改性研究新进展

环氧树脂是一种热固性树脂,固化后的环氧树脂的韧性较差,针对这一不足,详细介绍近几年来有关环氧树脂增韧改性的一些新的方法。     

环氧树脂的增强增韧

1 前言 环氧树脂(EP)问世60年以来以其优异性能至今保持着高性能高分子材料的地位.但是与热塑性树脂相比,环氧树脂最大缺点是其脆性.所以对EP的增韧研究由来已久,改性方法也多种多样,如用液态弹性体增韧;用交联的橡胶粒子增韧;用有机弹性体一无机填料复合改性;用核/壳型橡胶粒子改性;用热塑性工程合金塑料改性等.     

Fracture testing and toughening of epoxy resins

The tapered cantilever cleavage and the single-edge-notch tension fracture toughness tests have been shown to give similar results for several cured epoxy resin systems. Methods for the calculation of fracture energy and critical stress intensity factors are described and discussed. These tests have been used to study the influence of rubber modifiers (“Hycar” CTBN and “Blendex” 311) on the toughness of a conventional epoxy resin (“Epikote” 828) reacted with anhydride curing agents. The modifiers used increase fracture energies and stress intensity factors by factors of approximately 5 and 2 respectively.     

Ternary blends in the toughening of epoxy resins

The fracture properties of two types of ternary blends (amine terminated rubber/Bisphenol-A/DGEBA resin) have been studied. In the first type, B, setting was obtained by using piperidine as the hardener. In the second type, C, the rubber was used as both the hardener and the toughener. Both types showed an increased fracture resistance over the binary rubber/resin formulations. The drawback of the too high reaction rate shown by type B blends can be eliminated by using type C blends which can be easily B-staged.     

Core-shell particles designed for toughening the epoxy resins. II. Core-shell-particle-toughened epoxy resins

The diglycidyl ether of bisphenol A–m-phenylene diamine (DGEBA–MPDA) epoxy resin was toughened with various sizes and amounts of reactive core-shell particles (CSP) with butyl acrylate (BA) as a core and methyl methacrylate (MMA) copolymerized with various concentration of glycidyl methacrylate (GMA) as a shell. Ethylene glycol dimethacrylate (EGDMA) was used to crosslink either core or shell. Among the variables of incorporated CSP indicated above, the optimal design was to obtain the maximum plastic flow of epoxy matrix surrounding the cavitated CSP during the fracture test. It could be achieved by maximizing the content of GMA in a shell-crosslinked CSP, the particle size, and the content of CSP in the epoxy resin without causing the large-scale coagulations. The incorporation of reactive CSP could also accelerate the curing reaction of epoxy resins. Besides, it was able to increase the glass transition temperature of epoxy resins if the particle size ≤0.25 μm and the dispersion was globally uniform. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2313–2322, 1998     

Microstructural effects and the toughening of thermoplastic modified epoxy resins

We have studied an epoxy resin formulation consisting of the diglycidyl ether of bisphenol-A (DGEBA), modified with phenolic hydroxyl-terminated polysulfone (PSF) and cured with an aromatic amine curing agent, diaminodiphenyl sulfone (DDS). A range of microstructures and fracture properties have been obtained by controlling the formulation cure conditions (cure temperature and cure cycle in an isothermal mode). The chemical conversion of the cured resins has been monitored by near-infrared spectroscopy (NIR). Although only a single material formulation was used, three distinct types of microstructure were identified by scanning electron microscope (SEM) observations on samples prepared at different cure temperatures. Surprisingly, the thermal and fracture properties of the cured samples did not vary noticeably, in spite of the significant microstructure variations. The consistency of these fracture toughness results with cure temperature changes was an unexpected result in the light of our earlier observations of a strong dependence of fracture toughness on cure temperature in neat resin systems. The difference in behavior between neat and modified resins reveals that the fracture toughness of the latter is dependent on a combination of the microstructure and the matrix resin properties. This hypothesis was also supported by an observation of high fracture thoughness in a sample cured in a two-step process, which we believe is due to the optimum microstructure and matrix resin properties, being achieved separately during precure and postcure, respectively. The increase in fracture toughness values caused by the modification (ΔG_IC) was calculated from the fracture toughness values of neat and modified resins, prepared under the same cure conditions, using a proposed theoretical equation. © 1993 John Wiley & Sons, Inc.     

核壳聚合物增韧环氧树脂的进展

核壳聚合物（CSP）现已用于增韧环境树脂，它具有许多优点：预先设计的CSP在环氧基体中的形态、大小和分散状态与固化规范无关；在提高环氧树脂韧性的同时不降低玻璃化温度。本文综述了CSP／环氧共混物的性能和增韧机理。主要的增韧机理是CSP粒子空穴化，释放裂缝附近的三轴度，继而产生膨胀形变和剪切屈服。     

Matrix viscoelasticity: Controlling factor in the rubber toughening of epoxy resins

Our limited success in toughening methylene dianiline (MDA)-cured Epon 828, using varying rubber types, led to a study of the role of the matrix viscoelasticity in the toughening process. Two rubber types, with different interfacial bonding capabilities, poly(n-butyl acrylate)/15 wt % acrylonitrile/2 wt % acrylic acid and poly(n-butylacrylate)/15 wt % acrylonitrile, were incorporated into systems containing varying amine concentrations to control crosslink density. Impact strengths of controls and rubber-modified compositions increased with excess amine concentrations up to 70%. The impact strengths for the poly(n-butyl acrylate)/15 wt % acrylonitrile/2 wt % acrylic acid rubber-modified compositions were greater than their equivalent controls, with the effect being greater at a lower crosslink density. This study confirmed that the matrix viscoelasticity is the controlling parameter in the toughening process. The degree of rubber–epoxy interfacial bonding is also an important parameter to consider, if the matrix viscoelasticity permits toughening. A modified stress response model was used to explain the toughening phenomenon.     

New analytical methods for epoxy resins, 2. Two-dimensional chromatography

In order to gain information on the functionality type distribution and molar mass of bisphenol A based epoxy resins, on-line coupled two-dimensional chromatography was used. In the first chromatographic dimension, liquid chromatography at the critical point of adsorption separated the samples with respect to functionality. The functionality fractions were automatically transferred into size exclusion chromatography as the second dimension, where the fractions were separated with respect to their molar mass distribution. As a result of the two-dimensional experiment, the samples were mapped in contour plots, providing quantitative information on the interconnected parameters functionality, molar mass, and branching.     

Electrospun rubber/thermoplastic hybrid nanofibers for localized toughening effects in epoxy resins

Synthetic rubber/thermoplastic blends were electrospun from their solutions. The rubber was a solid acrylonitrile/butadiene/acrylic acid copolymer and the thermoplastic was polyacrylonitrile. The aims of this study were to identify suitable systems and processing conditions for obtaining rubber-based electrospun nanofibers, to investigate the ability of an epoxy resin system to impregnate and swell selected hybrid rubber/thermoplastic mats, and to assess the impact of the nanofibers on the resin morphology and curing behavior. In particular, electrospinning trials were carried out varying the composition of the feed solution and process parameters, such as the applied voltage, the flow rate, and tip-to-collector distance. The morphology of the hybrid mats was characterized by scanning electron microscopy and their thermal properties by thermogravimetry. An epoxy resin-mat monolayer was also prepared and its fracture surface inspected; both rubber nanoparticles and PAN nanofibers were evident. The highly corrugated fracture surfaces suggest activation of local epoxy-resin toughening mechanisms. Altogether, the results encouraged the application of hybrid mats as interleaves in high-performance carbon/epoxy composites to contrast delamination. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48501.