Model Adherend Surface Effects on Epoxy Cure Reactions

Adherend surface effects on the amine cure of epoxy resins were investivated using finely divided aluminum oxide as high surface area models for aluminum. Calorimetric analysis of simplified crosslinking systems revealed significantly faster reactions which led to lower glass transition temperature materials for activated aluminum oxide filled samples. A monofunctional amine and epoxy were then utilized to obtain soluble reaction products amenable to molecular characterization. These studies similarly showed an increase in the rate of epoxy consumption in the presence of activated aluminum oxide which was attributed to both an increase in the rate of amine addition to epoxy as well as to epoxy homopolymerization. The latter was not observed in the unfilled mixtures. Such changes in reaction mechanism at the adherend surface have implications for the strength and durability of actual adhesive bonds.     

Model Adherend Surface Effects on Epoxy Cure Reactions

Adherend surface effects on the amine cure of epoxy resins were investivated using finely divided aluminum oxide as high surface area models for aluminum. Calorimetric analysis of simplified crosslinking systems revealed significantly faster reactions which led to lower glass transition temperature materials for activated aluminum oxide filled samples. A monofunctional amine and epoxy were then utilized to obtain soluble reaction products amenable to molecular characterization. These studies similarly showed an increase in the rate of epoxy consumption in the presence of activated aluminum oxide which was attributed to both an increase in the rate of amine addition to epoxy as well as to epoxy homopolymerization. The latter was not observed in the unfilled mixtures. Such changes in reaction mechanism at the adherend surface have implications for the strength and durability of actual adhesive bonds.     

水性双组分环氧/胺体系技术研究

为了全面、深入介绍水性双组分环氧/胺体系的技术方向和路线,论述了双组分水性环氧/胺体系(Ⅰ型和Ⅱ型)技术的发展历程;概述了Ⅰ型和Ⅱ型体系的固化成膜原理和机理;研究了Ⅰ型和Ⅱ型体系水性环氧树脂与固化剂技术提升思路,如,Ⅰ型环氧树脂的物理改进和化学改进的思路,3类Ⅰ型固化剂的技术发展,Ⅱ型环氧树脂及固化剂的技术发展;介绍了环氧丙烯酸杂化新技术的原理和应用。指出,具有相容性好、涂膜初期耐水性好、与锌粉配伍性好且适用期长、高性价比等性能的环氧树脂/固化剂体系将成为未来的发展方向。     

胺类促进剂对环氧树脂/酸酐固化体系的影响

以液体四氢甲基苯酐为固化剂,选用了多种胺类促进剂(包括脂肪类乙醇胺、脂环胺、脂肪胺、季胺盐、脲类)对双酚A缩水甘油醚类环氧树脂固化体系进行研究.从固化促进剂的相容性、凝胶时间、玻璃化转化温度、可使用时间等方面确定最佳配方.研究表明,脂环胺(N,N-二甲环己胺)、脂肪胺[三(二甲胺基丙基)胺]、季胺盐(2,2-二甲基丙酸季胺盐)可以促进双酚A缩水甘油醚类环氧树脂/液体四氢甲基苯酐固化体系的固化,并能使该体系的固化温度从160℃降低到100～120℃,力学性能达到玻璃钢缠绕和灌封浇注料的要求.     

PEI及其改性物增韧环氧树脂研究

综述了Polyetherimide (PEI)及其改性物对环氧树脂的增韧研究进展。由于体系的相态结构是决定材料力学性能的重要因素 ,通过对PEI增韧TGDDM/DDS、Epikote82 8/DEAPA、TGAP/DAP、MY0 510 /DDS及HPT10 71/HPT10 61M等环氧树脂材料改性前后的相态结构和力学性能进行了分析比较 ,认为PEI对环氧树脂体系的增韧改性是成功的。     

酚醛改性胺环氧树脂固化剂研究进展

介绍了酚、醛改性胺类固化剂的合成反应原理、工艺路线、合成方法以及酚醛改性胺类固化剂产品型号、标准和技术指标方面存在的问题，建议尽快规范统一的标准。详细介绍了近年来该类固化剂的研究已从单纯的苯酚、甲醛对各种胺的改性。向着由多元化的酚、醛对各种胺进行改性的方向发展。描述了这类固化剂的主要品种及其优缺点并对市场前景进行了预测和展望。     

环氧树脂/胺基酰亚胺潜伏性固化体系非等温固化动力学研究

分别采用Kissinger模型和Flnn-Wall-Ozawa(FWO)模型研究了E-51型环氧树脂/胺基酰亚胺潜伏性固化体系的非等温固化动力学,得到了该体系在这2种模型下的固化反应活化能.分析了不同动力学模型对该体系固化反应动力学研究的影响.结果表明,由2种模型得到的固化动力学参数基本相近.E-51/胺基酰亚胺体系的固化反应具有变活化能特征,固化反应起始阶段的活化能较高,约为103～112 kJ/mol;当固化度为0.9时,活化能约为63～82 kJ/mol.     

聚醚胺/酚醛胺-环氧树脂体系的固化动力学研究

采用示差扫描量热法(DSC)研究了以聚醚胺/酚醛胺为固化剂的环氧树脂体系固化反应,在25~230℃范围内以不同的升温速率(5℃/min、10℃/min、15℃/min、20℃/min)对该体系的固化动力学参数分析。由Kisserger方程求得该体系固化反应的表观活化能为61.76 kJ/mol,频率因子A为7.1×107s-1;由Crane方程得出固化反应级数为1.116;并建立了固化动力学方程:-da/dty=k(1-a)1.116,其中。k=7.1×107exp(-7 429/t)。     

二缩水甘油二甘醇胺封端聚氨酯/环氧树脂复合体系的热力学性能研究

以二缩水甘油二甘醇胺(DGDGA)作为端-NCO型聚氨酯(PU)预聚体的封端剂,合成出了具有高反应活性的二缩水甘油二甘醇胺封端的聚氨酯(DGDGAPU)。并用其改性环氧树脂,得到了固化速度匹配、相容性好的聚氨酯/环氧树脂复合体系。采用红外光谱(FT-IR)法对其结构进行表征,采用TG研究其热性能,通过冲击、压缩等方法研究其力学性能,并用SEM分析发现其形成了交联紧密的DGDGAPU/EP网络。结果表明,在加入50%环氧树脂时体系力学性能最佳。     

环氧改性胺固化剂在施工中的应用

介绍改性胺固化剂在环氧体系施工中的作用 ,叙述了低成本、高性能、高效益的环氧涂料固化体系的优良特性     

聚醚酰亚胺/环氧树脂体系的固化及相分离行为研究

环氧树脂固化物本征的低韧性是限制其在复合材料应用的主要缺点之一。利用高性能热塑性树脂聚醚酰亚胺(PEI)与环氧树脂共混,系统研究了PEI在环氧树脂中的溶解行为、固化行为以及相分离行为。溶解试验表明:PEI与环氧齐聚物具有良好的相互溶解性;同时,PEI的加入降低了环氧树脂固化反应的活化能,但并没有改变其固化反应的机制。扫描电镜结果显示:随着PEI含量的增加,环氧/PEI浇铸体的相形貌从明显的分散颗粒相结构演变为双连续相结构和反转相结构。     

Toughening of Epoxy Resins by Amine Terminated Poly(arylene ether ketone)s having Pendant Tertiary Butyl Groups

Summary The objective of this study was to investigate the effects of the amine terminated poly(arylene ether ketone) (PAEK) oligomers as epoxy tougheners on the mechanical and thermal properties of diglycidyl ether of bisphenol A based epoxy resin. The reactive oligomers including pendant tertiary butyl groups were synthesized by nucleophilic aromatic substitution reaction and molecular weight of the oligomers were controlled through end group functionalization and characterized by FTIR spectroscopy. The stoichiometrical amount of the reactive oligomers as toughener and the curing agent, 4,4’-diaminodiphenyl sulfone (DDS) were mixed and degassed. The homogenous mixtures were cured at 120 °C into the preheated molds. The mechanical and thermal characterizations of toughened epoxy resin system were evaluated. It has been shown that the mechanical and thermal properties of toughened epoxy system vary as a function of the chemical structure and the concentration of reactive oligomers. The paper has been dedicated to Prof. Dr. Abdülkadir Kuyulu     

聚醚胺/酚醛胺-环氧树脂体系力学性能及其固化行为研究

对不同配比的聚醚胺/酚醛胺-环氧树脂体系的力学性能进行了研究,并采用示差扫描量热法(DSC),在25～230℃范围内以不同的升温速率(5℃/rmin、10℃/min、15℃/min、20℃/min)研究了以聚醚胺/酚醛胺为固化剂的环氧树脂体系固化行为,对其不同升温速率下的固化度进行了分析,采用T-β外推法得出该体系的起始固化温度、峰顶固化温度和终止固化温度等固化工艺参数.     

联苯型环氧树脂改性邻甲酚醛环氧树脂体系的固化反应动力学研究

联苯型二缩水甘油醚/邻甲酚醛环氧树脂按1∶4比例组成,体系用线性酚醛树脂为固化剂,咪唑为固化促进剂,通过差示扫描量热仪(DSC)研究了体系的非等温过程固化反应动力学,并用Kissinger和Ozawa方法分别求得体系固化反应的表观活化能△E为71.79和75.02k J/mol,根据Crane理论计算得到该体系的固化反应级数n=0.93,在不同升温速率下的频率因子的平均值A为6.73×106,从而推断出该体系动力学模型,为该体系作为集成电路封装材料的应用工艺提供了基础数据。     

一种重要的环氧树脂胺类固化剂—间苯二甲胺

本文对苯二甲胺固化剂的国外概况、各种理化性能、制备方法、以及在环氧树脂固化剂等方面的各种应用情况,作了介绍与详述.     

有机硅/聚醚胺复合改性环氧树脂合成及性能

以二甲基二乙氧基硅烷、γ-氨丙基三乙氧基硅烷、二苯基二甲氧基硅烷为单体,通过水解、缩聚制备了含有氨基活性功能基团的有机硅低聚物(PS),然后以PS与聚醚胺与环氧树脂进行固化交联得到有机硅改性环氧树脂,研究探讨了PS的不同添加量对改性环氧树脂耐热性、力学性能及吸水性能的影响。结果表明,当PS添加量为基体树脂质量的30%时,改性树脂的耐热性能有明显提高,800℃残留量为26.45%,拉伸强度为68.27 MPa,弯曲强度为81.68 MPa,与水表面接触角为109.3°,吸水率为2.59%,比未改性树脂分别提高了17.24%、6.6%、17.3%、21.3%和降低了0.12%。     

Studies on Dielectric and UV Shielding Properties of Epoxy Functionalized Alumina/Silane-Modified Amine Epoxy Nanocomposites

In the present work, 3-glycidyloxypropyltrimethoxysilane functionalized alumina (F-Al₂O₃) was prepared and the formation of chemical bonding was confirmed with FTIR spectroscopy. Varying weight percentages of (5, 10, 15 and 20 wt%) glycidyl F-Al₂O₃ were reinforced with blend of diaminophenoxydimethylsilane and epoxy resin and then cured with diamonodiphenylmethane. The surface morphology of samples was analyzed before and after UV exposure for 168 h using SEM. The 20 wt% F-Al₂O₃ reinforced epoxy nanocomposite sample possesses higher thermal stability, higher dielectric constant and better UV radiation resistant properties than that of other weight percentages of F-Al₂O₃ reinforced epoxy nanocomposites.     

Off-Optimum Cure of Aerospace Epoxy Adhesives

Four epoxy film adhesives used in aircraft manufacture and repair have been examined to establish the effect of deviation from the cure cycle specified by the manufacturer. In addition to the variation of the cure cycle, two surface preparations of the aluminium adherends (chromic acid etch or grit blast followed by silane treatment) were evaluated. Thermal analysis was used to examine the cure envelope of the adhesive, and its extent of cure and glass transition temperature. The adhesive properties were assessed by shear strength (in both single lap joints and in Iosipescu configuration), durability (Boeing wedge test) and chemical resistance to selected aggressive fluids. The sensitivity of the performance of a particular adhesive to offoptimum cure conditions depends on its composition and needs to be determined, not predicted.     

Off-Optimum Cure of Aerospace Epoxy Adhesives

Four epoxy film adhesives used in aircraft manufacture and repair have been examined to establish the effect of deviation from the cure cycle specified by the manufacturer. In addition to the variation of the cure cycle, two surface preparations of the aluminium adherends (chromic acid etch or grit blast followed by silane treatment) were evaluated. Thermal analysis was used to examine the cure envelope of the adhesive, and its extent of cure and glass transition temperature. The adhesive properties were assessed by shear strength (in both single lap joints and in Iosipescu configuration), durability (Boeing wedge test) and chemical resistance to selected aggressive fluids. The sensitivity of the performance of a particular adhesive to offoptimum cure conditions depends on its composition and needs to be determined, not predicted.     

Reactions of Living Polytetrahydrofuran with Amines V - Tertiary Amine Terminated Polybutadienes; The Synthesis of Novel Ionically Linked Block Copolymers

The reactions of mono- and difunctional tertiary amine ended polybutadienes with mono- and difunctional living cationic poly THF have been studied. It is shown that the reaction to form quaternary ammonium linking groups takes place rapidly in all cases, and AB. ABA, BAB and (AB) block copolymers have been prepared. The efficiency of the process is extremely high and the degree of conversion is essentially controlled by the efficiency with which the terminal tertiary amine groups can be introduced on to the polybutadiene. The block copolymers show anomalous behaviour on gel permeation chromatography columns and this has been related to a specific interaction of the created ionic groups with polar species on the column packing. This effect is greatest with (AB) block copolymers where substantial proportions are retained indefinitely on the columns.