丙烯酸酯无皂水溶胶涂料热固化性能的研究

用红外光谱法和差热分析法研究了热固性丙烯酸酯无皂水溶胶与六甲氧基甲基三聚氰胺(HMMM)的固化过程。实验表明水溶胶的固化是分两步进行的,羟基和羧基与固化剂HMMM上的甲氧基在不同的温度区间交联固化,并且羟基的交联固化反应温度低于羧基的。同时,考察了固化剂用量对固化温度和固化度的影响。     

Cohesive Zone Model Characterization of the Adhesive Hysol EA-9394

Abstract

The cohesive zone model approach is attractive for the analysis of failure of adhesively bonded structures. While the numerical implementation of cohesive elements has been well established, there remains a lack of cohesive material data. The present paper contributes to efforts to fill this void. An investigation of crack growth in the widely used structural adhesive Hysol EA-9394 is presented, and the adhesive is characterized by a cohesive zone law. Crack growth experiments were performed on specimens consisting of aluminum adherends bonded by use of the adhesive. Measurements of the surface topography leading reconstruction of fracture processes indicate that plastic deformation is absent during fracture. Thus, the cohesive zone law can directly be determined from the energy release rate and the material separation measured at the initial crack tip. The cohesive zone law is then applied in finite element model to predict crack growth. The predicted strain fields during crack growth are well matched to those obtained by digital image correlation measurements. An independent set of crack growth experiments was performed, and finite element models based on the cohesive law were used to predict the outcome of these experiments. Again good agreement between simulation and experiment was obtained. The results give confidence that the cohesive zone model parameters are transferable to the analysis of structures bonded with the adhesive Hysol EA-9394 in general. A comparison of the cohesive zone law for Hysol EA-9394 demonstrates that this adhesive possesses high strength and moderate toughness. Limits to the transferability regime are discussed.     

双环戊二烯酚型环氧树脂的固化反应研究

研究了ＤＣＰＤ酚环氧树脂与酸酐及胺类固化剂的固化反应活性。通过ＤＳＣ热分析方法表征了ＤＣＰＤ酚环氧树脂与甲基六氢苯酐（ＭeHHPA)及４,４′－二氨基二苯甲烷（ＤＤＭ）的固化反应过程,测定了反应热焓,并分析了固化温度、时间及固化剂结构等对ＤＣＰＤ酚环氧树脂凝胶时间及固化度的影响,探讨了温度、时间对ＤＣＰＤ酚环氧树脂固化反应活性的影响。     

新型环氧树脂胶粘剂的固化动力学研究

在不同升温速率下采用非等温差示扫描量热（DSC）技术对一种新型改性环氧树脂胶粘剂的固化反应过程进行了跟踪,并利用Kissinger、crane方程以及Arrhenius方程对该固化反应进行了动力学分析。结果表明,该固化反应的活化能为59.18kJ／mol,反应级数为0．89;结合Dsc谱图确定其固化工艺为130℃／1h＋150℃／2h＋175℃／3h。     

Effects of adhesive modulus and curing conditions on curing behavior of silicate based ceramic coatings on carbon fiber reinforced resin matrix composites

Sodium silicate based ceramic coatings were prepared on the surface of carbon fiber reinforced epoxy resin matrix composite. The coatings were obtained by curing the mixture of silicate adhesive, SiO₂ or Na₂SiF₆ as curing agent, and YSZ and Al₂O₃ as filler. The effects of adhesive modulus, curing agent, curing temperature and time on curing behavior of the coatings were investigated. The results indicated that the coating obtained from 2.7 modulus of silicate adhesive was dense, cohesiveness, uniform and continuous. As curing agent, SiO₂ could promote curing better than Na₂SiF₆, achieving complete curing of the coating. And the coating containing SiO₂ as curing agent was dense, flat and well adhered to the substrate. The curing behavior of coatings was significantly affected by curing temperature and time. The coatings could be cured completely with the increase of curing temperature. The best curing result was obtained at 100 °C curing temperature. Also the experimental results showed that the characteristics of coatings were improved to a certain extent by prolonging the curing time.     

环氧树脂涂料用脂肪族二胺加成物固化剂

介绍了一类性能独特的脂肪族和脂环族二胺加成物环氧固化剂,其毒性低、气味小。用其制备的涂料具有良好的耐化学腐蚀性、高硬度和良好的光泽性。     

水中固化环氧胶粘剂的研究

以E-44环氧树脂为主剂，以低分子聚酰胺和酚醛胺混合物(质量比为1：1)为固化剂．胶中还包含活性稀释剂、偶联剂、填料等辅助成分，制成双组分水下胶粘剂。该胶在25℃水中72h即可固化．剪切强度可达6．5MPa。该胶使用方便，性能优良，已实现工业化生产。     

微波固化碳纤维/环氧树脂胶的研究

介绍了微波固化热固性树脂的原理和特点,利用微波炉设备和选择的一种较好微波吸收剂,探讨了微波固化工艺。研究表明,利用微波固化环氧胶时,不仅固化时间短,而且剪切强度优于加热固化。     

Selected aspects of epoxy adhesive compositions curing process

The paper focuses on selected parameters of curing process – temperature and time. The tests aimed at evaluating the impact of short-term thermal recuring on 1050A and 2017A aluminium alloy sheet adhesive joints strength. Joints were formed with two different adhesives, the main component of which was in both cases epoxy resin Epidian 53 and two different cure agents – poliamineamide C (PAC) and triethylenetetraamine (PF) curing agents. Curing conditions – first curing time, recuring time and recuring temperature – were modified for each of the four tests conducted. For the sake of comparative analysis, adhesive joints were subjected to a single-stage cure cycle at ambient temperature. A two-stage cure cycle of both Epidian 53 compositions at 80?°C for 1 and 2?h produces a material of different mechanical properties than the same material which submits a single-stage cure cycle at ambient temperature, as well as at 60?°C for 30?min. Simultaneously, Epidian 53/PF/100:50 composition proves to produce higher joint strength after recuring than Epidian 53/PAC/100:80; the strength of a joint formed with the former composition increases up to 50% when compared with joints subjected to a single-stage cure cycle. Moreover, tests show that recuring of the adhesive joint formed with both compositions at 60?°C for 30?min does not have a considerable influence on either 1050A or 2017A aluminium adhesive joint strength.     

新型环氧树脂固化剂的合成及其环氧胶粘剂

以4,4’-二氨基二苯甲烷为原料,经乙酰化、硝化、酸解、还原、中和5步反应合成得到了一种新型环氧树脂固化剂,即3,3’,4,4’-四氨基二苯甲烷,并通过FT—IR分析及熔点测定对其进行了表征。此外,对改性环氧树脂／3,3’,4,4’-四氨基二苯甲烷体系也作了性能研究。     

Synthesis,curing behavior and thermal properties of fluorene-containing benzoxazines based on linear and branched butylamines

A series of fluorene-containing benzoxazine monomers based on linear and branched butylamines were successfully synthesized in high purity and good yield through a facile one-pot procedure by the reaction of 9,9-bis-(4-hydroxyphenyl)-fluorene with paraformaldehyde and isomeric butylamines. The chemical structures of the target monomers were characterized by Fourier transform infrared (FT-IR), Elemental analysis, ¹H and ¹³C nuclear magnetic resonance (NMR). The curing behavior of benzoxazine monomers was studied by differential scanning calorimetry (DSC) and FT-IR. The thermal properties of cured polybenzoxazines were measured by DSC and thermogravimetric analysis (TGA). The results reveal that the polarity of solvent and the basicity of butylamines produce clear effects on the synthesis of the butylamine-based benzoxazine monomers. Also, the basicity and steric effect of butylamines exhibit significant effects on the curing behavior of benzoxazine monomers and the thermal properties of their polymers. The glass transition temperature and thermal stability of branched butylamine-based polybenzoxazines are higher than those of the corresponding linear butylamine-based polybenzoxazine and traditional bisphenol A-based polybenzoxazines.     

环氧树脂胶黏剂在石墨粘接接头的热分解动力学

引言 与传统的铆接、螺栓连接工艺相比,粘接技术因具有操作灵活、简便、生产效率高、生产成本低等优点,而广泛用于化工、汽车、航空、航天等现代结构工程,在工程设计和制造领域的应用持续增长[1-3].     

Elongational behavior of epoxy during curing

Elongational behavior of epoxy (epoxy/curing agent = 100/0.5, w/w) cured at various conditions over the critical gelation time was investigated. Dynamic viscoelastic measurements of the epoxy system were performed and the critical gelation time of epoxy was determined according to the frequency dependence of G′ and G″ proposed by Winter and Chambon. Elongational behavior of epoxy cured for various times were measured. Epoxy, cured over the critical gelation time, showed strain hardening and elongational behavior similar to a crosslinked rubber. Increase of elongational viscosity of the sample occurred early, and the sample broke at small strain as curing time increased. The effect of strain rate on the elongational stress of epoxy cured near the critical gelation time was measured at various strain rates. For epoxy cured for critical gelation time only, high stress at a small strain rate was represented as strain rate increased. When increasing curing time further, the tensile stress converged on a single curve regardless of strain rate, and samples broke at nearly the same stress and strain. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical behavior of polyurethane adhesive bonded joints as a function of temperature and humidity

The temperature and humidity were found to be the most effective parameters in the behavior of polyurethane flexible adhesive bonded aluminum joints. In order to obtain the effect of environment on bond strength, toughness, failure displacement, joints stiffness and failure model, in this work, aluminum single-lap joints were tested under various temperatures (25, 40, 60 and 80 °C) and relative humidity (RH, 55, 65, 75, 85, 95 and 99%) using an environmental chamber. The results showed that as the humidity increased from 55 to 99%, bond strength decreased as linear function. As the temperature increased from 25 to 80 °C, the bond strength decreased as exponential function. The joints stiffness reduced gradually with the increase of temperature and humidity. The analysis of the failure section of the ageing joints showed that the humidity caused the transition of the failure model, and the increase of the temperature promoted the change of the failure model. Besides, at low humidity (55 and 65%), failure displacement decreased gradually with the increase of temperature, and at high humidity (95 and 99%), failure displacement increased. This study will help engineers design a reliable, safe and effective bonding structure. And it is conducive to solve the problem of joint strength degradation in the hygrothermal environment.     

Curing kinetics and properties of epoxy resin-fluorenyl diamine systems

Diglycidyl ether of bisphenol fluorene (DGEBF), 9,9-bis-(4-aminophenyl)-fluorene (BPF) and 9,9-bis-(3-methyl-4-aminophenyl)-fluorene (BMAPF) were synthesized to introduce more aromatic structures into the epoxy systems, and their chemical structures were characterized with FTIR, NMR and MS analyses. The curing kinetics of fluorenyl diamines with different epoxy resins including DGEBF, cycloaliphatic epoxy resin (TDE-85) and diglycidyl ether of bisphenol A (DGEBA) was investigated using non-isothermal differential scanning calorimetry (DSC), and determined by Kissinger, Ozawa and Crane methods. The thermal properties of obtained polymers were evaluated with dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). The results show that the values of activation energy (E_a) are strongly dependent on the structures of epoxy resin and curing agent. The curing reactivity of epoxy system is restrained by the introduction of rigid fluorene into chain backbone and flexible methyl into side groups. The cured DGEBF/fluorenyl diamine systems exhibit remarkably higher glass transition temperature, better thermal stability and lower moisture absorption compared to those of DGEBA/fluorenyl diamine systems, and display approximate heat resistance and much better moisture resistance relative to those of TDE-85/fluorenyl diamine systems.     

CA型环氧树脂固化剂性能研究

用ＩＲ光谱表征了自制ＣＡ型环氧树脂固化剂的结构特点,测定了ＣＡ型固化剂的固化特性,固化树脂的性能和增塑效果。实验结果表明,ＣＡ型固化剂能使环氧树脂涂料在潮湿表面和带油表面上固化成膜,其固化的树脂具有良好的耐蚀性,冲击强度较二乙撑三胺固化的树脂有较大提高,同时也是一种较好的环氧树脂用增塑剂。     

Synthesis and characterization of polyaniline nanorods as curing agent and nanofiller for epoxy matrix composite

Novel PANI nanorods with average diameter of 21-53 nm and length of 0.5-1 μm were synthesized by dispersion polymerization method. The morphology of obtained PANI nanorods was significantly dependent on the type of salt, stirring, and polymerization temperature. Dispersion polymerization with FeCl₃ produced longer nanorods than ammonium persulfate (APS) and magnetic stirring decreased the length of nanorods. While the average diameter of PANI nanorods decreased with increasing reaction temperature, the electrical conductivity dropped considerable at high polymerization temperature due to the increment of insulating emeraldine base. Dynamic differential scanning calorimetry (DSC) study showed that the heat of cure was independent of heating rate. On the contrary, the heat of cure was proportional to the content of PANI nanorods as a role of curing agent. Isothermal DSC study revealed that the cure behavior of LCE/PANI nanorod system was an auto-catalyzed reaction. Thermogravimetric analysis (TGA) indicated that the thermal stability of cured LCE/PANI nanocomposite was significantly dependent on the PANI nanorod composition. In addition, the electrical conductivity of LCE/PANI nanocomposite materials was higher than that of conventional epoxy composites. Therefore, PANI nanorods played a role of curing agent owing to the existent amine group and acted as reinforcing filler for cured LCE nanocomposites.     

动态热机械分析法对环氧树脂固化程度的研究

以动态热机械分析仪研究环氧树脂的固化程度 ,发现样品固化不完全 ,在分析过程中的加热效应使其固化完全     

Jatropha curcas oil based alkyd/epoxy/graphene oxide (GO) bionanocomposites: Effect of GO on curing,mechanical and thermal properties

Jatropha curcas oil based alkyd/epoxy/GO bionanocomposites were prepared by direct solution blending of alkyd/epoxy blend matrix with GO nano filler. Structures and properties of the bionanocomposites were characterized with Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, thermogravimetric analysis, and tensile testing. X-ray diffraction and transmission electron microscopy study demonstrates the formation of highly exfoliated GO layers and its homogeneous dispersion throughout the polymer matrix with 1 and 3 wt% GO. However, the intercalated structure is predominant with 5 wt% GO. The homogeneous dispersion and the strong interaction of the GO layers and the polymer matrix induced the significant improvement in thermal and mechanical properties of the bionanocomposites. The tensile strength and elastic modulus of the bionanocomposite increased by 133% and 68% respectively with 3 wt% GO loading. The thermal stability of the bionanocomposite improved by 39 °C and T_g is shifted toward higher temperature by 20 °C as compared to the pristine polymer. Incorporation of GO significantly decreases the curing time of the alkyd/epoxy resin blend.     

环氧建筑结构胶固化速度的调整

在建筑结构加固领域用环氧树脂中,选一种高活性酚醛胺固化剂HD—SG和一种低活性改性芳香胺固化剂HD—MG,通过调整HD-SG／HD—MG的质量比,可以得到不同活性的环氧树脂固化剂,并对固化物力学性能进行研究。