Viscoelastic and Processing Effects on the Fiber-Matrix Interphase Strength. Part II. The Effects of Cure Temperature Time and Curing Agent Content

The effects of curing agent content, cure temperature and time on the adhesion strength between carbon fibers (treated with epoxy sizing) and a thermosetting epoxy (Epon 815) are studied using the single fiber fragmentation test procedure. Theoretical equations describing a majority of the phenomena affecting the adhesion process are also reviewed. The possibility of superposition between percent curing agent content, cure temperature and time is illustrated based on the analytical models presented. Experimental data are presented in the form of percent relative frequency histograms for the fiber fragments in a collective fashion. Such presentation of the data allows for interpretation of the skewness in the data population. Optimum curing agent, cure temperature and time values resulting in highest interfacial strength are also determined.     

室温固化耐温150℃环氧树脂胶粘剂的制备与性能研究

采用耐热的二苯甲酮四酸二酐(BTDA)固化四官能度缩水甘油胺环氧树脂,制得了室温固化(RTV)耐热的环氧树脂(EP)胶粘剂。探讨了体系中n(环氧基团)∶n(酸酐基团)比值、促进剂用量以及填料的选择对胶粘剂性能的影响。实验结果表明,当n(环氧基团)∶n(酸酐基团)=1∶1、w(促进剂)=1%(占EP的质量分数)且以碳纤维作为填料时,胶粘剂性能最佳,其室温剪切强度为13.91 MPa,150℃剪切强度为10.63 MPa。     

Viscoelastic and Processing Effects on the Fiber-Matrix Interphase Strength. Part I. The Effects of Loading Rate, Test Temperature, Fiber Sizing and Global Strain Level

The effects of loading rate, fiber sizing, test temperature and global strain level on the adhesion strength between carbon fibers and a thermosetting epoxy (Epon 815) are studied using the single fiber fragmentation test procedure. Analytical methodology describing the viscoelastic behavior observed is also presented. The possibility of rate-temperature-interphase thickness superposition for the interfacial strength function is illustrated based on the analytical models discussed. Experimental data are discussed using Weibull statistics and also presented in the form of percent relative frequency histograms for the fiber fragments in a collective fashion. The use of histograms allows for interpretation of the skewness in the data population.     

Viscoelastic and Processing Effects on the Fiber-Matrix Interphase Strength. Part I. The Effects of Loading Rate,Test Temperature,Fiber Sizing and Global Strain Level

The effects of loading rate, fiber sizing, test temperature and global strain level on the adhesion strength between carbon fibers and a thermosetting epoxy (Epon 815) are studied using the single fiber fragmentation test procedure. Analytical methodology describing the viscoelastic behavior observed is also presented. The possibility of rate-temperature-interphase thickness superposition for the interfacial strength function is illustrated based on the analytical models discussed. Experimental data are discussed using Weibull statistics and also presented in the form of percent relative frequency histograms for the fiber fragments in a collective fashion. The use of histograms allows for interpretation of the skewness in the data population.     

双组分高强度环氧胶粘剂的研制

根据车间内钢梁上吊车轨道安装底板与钢梁粘接的具体要求,研制了一种中温固化双组分环氧胶粘剂。探讨了E-51、E-39D和纳米碳酸钙用量对甲组分粘度的影响,测试了不同促进剂的胶粘剂凝胶时间并研究了粘接表面处理、中温固化时间对胶粘剂剪切强度的影响。结果表明,通过选用不同粘度的环氧树脂并添加纳米碳酸钙,控制甲组分粘度在8～20Pa.s,选用促进剂M3份,表面制备并采用偶联剂处理后,100℃下固化2h后,该胶铝-铝、钢-钢剪切强度可达45MPa和51MPa,实现了胶粘体系中温高强度快速固化。室温放置20h后钢-钢剪切强度为5.8MPa,可以安装加热设备以便后固化。     

Cure behaviour of epoxy resin matrices for carbon fibre composites

The cure behaviour of two resin formulations (with high and low curing agent content respectively) of an epoxy resin system, used as matrix for carbon fibre composites, was studied through calorimetric analysis. The aim of this work is to investigate the kinetics of this specific epoxy system in order to be able to choose a proper set of processing parameters which will give good composite material properties. The shape of the conversion curves gives evidence of the differences in the cure kinetics of the two systems. Furthermore, the values of the activation energies were determined both for formulation in the conversion range where vitrification occurs, following a phenomenological approach. These values give an indication of the differences in the curing mechanisms, when varying the content of curing agent. In particular, for both systems, the same reaction represents the onset of the cure process, ie the autocatalytic epoxy ring opening through addition reaction to the primary amine. This reaction dominates the entire cure process of the epoxy formulation at high curing agent content. Conversely, in the formulations with a low curing agent content, after depletion of the primary amines, different reactions may take place (with secondary amines and hydroxyl groups), depending on the cure temperature and the resin viscosity. © 1999 Society of Chemical Industry     

The effect of curing temperature on thermal,physical and mechanical characteristics of two types of adhesives for aerospace structures

The effects of cure temperatures on the thermal, physical and mechanical characteristics of two types of thermosetting structural epoxy film adhesives were determined in detail. The aim of this paper is to assess the effect of cure temperatures (82–121 °C) on the degree of cure of the two adhesives and the relevant void formations that need to be addressed in bonded part production and repair. Two thermal parameters were used to characterize the advancement of the reaction, such as degree of cure and glass transition temperature. The joint properties with respect to the cure temperatures were characterized by void content and bond-line thickness measurements and lap shear strength tests. Experimental results presented that all lap shear strengths were well within minimum shear strength (29 MPa) required by the specification of the film-type adhesive. However, the lap shear strength testing after aging at 82 °C and 95%R.H for 1000 h showed that the improved durability when the adhesive is cured at 121 °C did not occur for the 82 °C cure. Low curing conversion (75–77% degree of cure) combined with high voids (over 2 areal%) has a catastrophic effect on the bonding qualities at the metal-adhesive interface and due to lack of cohesion in the adhesive. The changes in the interface caused by the low temperature curing may contribute to an increased susceptibility of the bonded joint to moisture and consequent bond-line degradation.     

缠绕复合材料固化工艺研究

生产连续玻璃纤维缠绕厚壁管时,在环氧树脂—酸酐固化体系中加入不同含量的促进剂,采用一次固化的方法,通过产生不同的固化速率达到分层固化的目的。结果表明,在一次固化时,固化速率从内层到外层逐步降低,减小了固化应力对厚壁管状产品内径圆度的影响,达到了分层固化的效果,提高了产品质量和生产效率。     

聚氨酯改性中温快速固化环氧粘合剂的制备与应用

以聚四氢呋喃醚、异佛尔酮二异氰酸酯、2-乙基咪唑为原料,合成了以2-乙基咪唑封端的聚氨酯,并用于改性环氧树脂E-44.利用傅立叶红外分析仪、示差扫描量热仪、拉伸试验机等手段对其与环氧树脂混合物的凝胶时间、固化温度、解封情况、拉伸剪切强度等性能进行了研究.结果表明,咪唑封端的聚氨酯可以在130℃下较好地解封,每10份E-...     

中温固化阻燃结构胶膜流变特性与蜂窝粘接性能

研究了用于蜂窝夹层结构粘接的阻燃结构胶膜的化学流变特性与蜂窝粘接性能。通过流变仪研究了胶膜固化过程中化学黏度的变化,考察了固化反应(温度、时间)、阻燃剂、增韧剂对体系化学流变特性的影响。分析了流变特性和胶瘤形成在蜂窝夹层结构粘接过程中的作用,并测试了蜂窝夹层结构的剥离和平面拉伸性能。结果表明:阻燃剂的加入使得体系100℃前的黏度有所升高,固化活性略有降低,最低黏度温度从112℃推迟到120℃;加入增韧剂后的胶黏剂的黏度显著提高,制备的阻燃胶膜最低黏度在50Pa.s左右,固化过程中具有适宜的流动性和胶瘤形状,固化后具有较高的滚筒剥离强度和平面拉伸强度。     

固化剂对低温固化环氧建筑胶性能的影响

研究了6种不同固化体系在-12～0℃温度下的固化情况,探讨了不同固化剂对胶粘剂固化反应速度、压缩强度及钢一钢拉伸剪切强度的影响。试验结果表明,MS-0021固化剂各项性能优于其他固化剂,其压缩强度值为62．56MPa,钢－钢拉伸剪切强度值为1523MPa,可满足胶粘剂的冬季施工要求。     

快速固化环氧树脂胶黏剂的研究

介绍了一种新型快速固化环氧胶黏剂的研制过程及其性能。选用不同固化剂和增韧剂,以及通过调整固化剂和增韧剂的添加量,对胶黏剂配方进行了优选。在固化工艺方面,研究了固化剂含量和固化温度对于凝胶时间的影响。当增韧剂Q含量在15—20份(质量)时,固化剂在21—24份(质量)时,胶黏剂的剪切强度和剥离强度最佳。结果表明,所研制的胶黏剂具有良好的耐湿热老化和耐介质性能,该胶黏剂同时具有胶接强度高和固化工艺方便的优点。     

室温固化高剥离耐热环氧树脂胶粘剂

介绍了一种具有高剥离强度和剪切强度的室温固化耐热胶粘剂。室温固化10d后,室温剥离强度可达到7．0kN／m;室温剪切强度为30．8MPa,150℃剪切强度可达14．5MPa。重点讨论了环氧树脂种类、复配合固化剂比例以及促进剂用量对胶粘剂粘接强度和耐热性能的影响。     

Effects of applied pressure and temperature during curing operation on the strength of tubular single-lap adhesive joints

Adhesive joints have been widely used for fastening thin adherends because they can distribute the load over a larger area than the mechanical joint, require no holes, add very little weight to the structure and have superior fatigue resistance. However, the load capabilities of adhesive joints are affected by both applied pressure and temperature during cure, as well as by service environments because the adhesion characteristics of adhesives are very sensitive to manufacturing and environmental conditions. In this study, the tensile load capabilities of tubular single-lap adhesive joints with an epoxy adhesive were experimentally investigated with respect to service temperature and the applied pressure and temperature during curing operation. The effects of the applied pressure on the tensile load capabilities of tubular single-lap adhesive joints were studied by measuring the actual cure finish temperature using thermocouples and dielectrometry. From the experiments, it was found that the actual cure finish temperature of tubular single-lap adhesive joints increased as applied pressure increased, which increased residual thermal stress in the adhesive layer to decrease the load capabilities of adhesive joints. From finite element analysis and experimental results of tubular singlelap adhesive joints, the optimal geometry condition for adhesive joints was also investigated.     

固化温度及填料对文物环氧胶粘剂性能的影响

研究了固化温度和填料对文物用双组分环氧胶粘剂力学性能的影响.红外分析表明,目前文物界普遍使用的国产3A万能胶,其主要组分为双酚A环氧树脂和脂肪胺/聚酰胺固化剂.以其作为研究对象,确定了适当的固化温度和填料用量,使环氧胶粘剂具有较好的操作性和粘接强度.     

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。     

Mechanical properties of cryogenic epoxy adhesives: Effects of mixed curing agent content

Phenyl glycidyl ether was used to react with solid metaphenylene diamine (MPDA) to produce N-(3-phenoxy-2-hydroxypropyl)-1,3-benzenediamine (NPHB). MPDA was intentionally formulated to have an excessive amount to obtain a new liquid MPDA–NPHB mixture. The mixed curing agent was indicated to have a few advantages over MPDA. The mixed curing agent was then used to cure diglycidyl ether of bisphenol A as cryogenic epoxy adhesive. The effects of the MPDA–NPHB content were systematically studied on the impact strength and shear strength at both room temperature and cryogenic nitrogen temperature of the epoxy adhesive. Moreover, two coupling agents with various contents were used to further enhance the shear strength of the optimal cryogenic epoxy adhesive. Finally, differential scanning calorimetry analysis showed that the modified adhesive showed a higher glass transition temperature than the unmodified adhesive.     

聚氨酯改性环氧胶粘剂的合成及性能研究

合成了具有反应活性的端环氧基聚氨酯,对其进行了初步的结构定性分析,并且研究了用端环氧基聚氨酯对环氧胶粘剂的改性,考查了端环氧基聚氨酯与环氧树脂的配比、填充料与树脂的配比、固化剂用量、固化温度等因素对胶粘剂强度的影响。该胶对黄铜粘接的剪切强度达30 MPa。     

室温固化厚胶层高强度环氧胶粘剂

采用环氧树脂予先与端羧基液体丁腈橡胶接枝以及合成子主链上带有多个醚键的二胺作固化剂，使调制的双组份糊状室温固化型环氧胶粘剂的甲、乙两组份均具有内增韬机制的双组份糊状室温固化型环氧胶粘剂的甲使得到的室温固化环氧胶具有极高剪切和剥离强度，并展现了厚胶层条件下仍具有高强度的特点。     

潜伏型环氧固化剂甲基异丁基酮二亚胺的合成及工艺优化

间苯二甲胺（MXDA）与甲基异丁基酮（MIBK）合成的甲基异丁基酮二亚胺（MIBKDI）,是单组分环氧胶常用的潜伏型固化剂。反应残余的MXDA,可直接与环氧树脂发生交联,显著降低储存稳定性。工业生产通过超高酮胺比使MXDA充分转化,但MIBK损失大、回收能耗高。本研究首先采用正交实验对反应温度、时间和酮胺比进行权重分析和因素效应分析,然后通过单因素实验系统研究反应时间、酮胺比对MXDA转化率的影响。结果表明,酮胺摩尔比超过5∶1（反应温度170℃、时间4 h）制备的固化剂,储存稳定性满足市场需求。在典型条件下,环氧树脂完全固化后剪切强度12.9 MPa,拉伸强度19.2 MPa,达到国家标准GB/T 2567—2008要求。与工业方案相比,酮胺比优化为5∶1以后,能耗大大降低,同时MIBK消耗有效节约,总成本得到客观降低。