水下环氧树脂胶粘剂用水下固化剂的性能研究

目前可用于水下粘接的EP(环氧树脂)胶粘剂用水下固化剂种类不多,主要是一些憎水类改性胺固化剂(如810和301P等)。以不同种类的水下固化剂作为试验对象,着重探讨了水下固化剂的本体黏度、相应水下EP胶粘剂的某些性能(如水下凝胶时间、水下拉伸剪切强度及水下压缩强度等)。研究结果表明:水下EP胶粘剂的适宜凝胶时间为1h左右;水膜隔离胶粘剂/被粘物的界面问题只影响拉伸剪切强度,而不影响压缩剪切强度,故水下固化剂的憎水性良好时,相应EP胶粘剂的压缩强度相对较高,但其钢/钢拉伸剪切强度会受到一定的影响;810和301P具有一定的憎水性,并且相应EP胶粘剂的水下凝胶时间均为1h左右,故不同黏度的810和301P复配可制得综合性能更好的水下EP胶粘剂。     

The role of wood extractives in structural hardwood bonding and their influence on different adhesive systems

Bonding of hardwood for structural applications is a complex process. Various factors influence the bond performance and the interface area is considered the most crucial part. The chemical composition of the interface, e.g. wood extractives, is expected to influence the bonding of hardwoods. The subject of this study was to determine the influence of seven model substances that represent common wood extractives on different adhesive systems namely one-component polyurethane, two-component polyurethane, melamine urea formaldehyde and phenol resorcinol formaldehyde. The influence of the model substances on the cross-linking behavior of the adhesives was determined by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and on the rheological properties in terms of gel point and storage modulus. In addition, model substances characteristic for selected wood extractives were applied to the surface of European beech wood [Fagus sylvatica L.] before bonding and consequently tested in tensile shear mode according to EN 302-1. The ATR-FTIR spectra showed an influence of some substances on the crosslinking for all adhesive systems. Further, the curing process was mostly accelerated for phenol resorcinol formaldehyde, while melamine urea formaldehyde and polyurethane showed a less negative change in rheological behavior. The mechanical strength of beech wood bonds at room climate indicated only minor influence of model substances, but samples tested in wet conditions demonstrated a significant effect on some adhesive systems. It was concluded, that polyurethane adhesives degrade by acid substances and melamine urea formaldehyde by starch and gallic acid. Phenol resorcinol formaldehyde system was influenced negatively by starch and acids.     

丙烯酸酯改性交联型水性聚氨酯胶黏剂

以异佛尔酮二异氰酸酯(IPDI)、聚己二酸-1,4-丁二醇酯二醇(PBA)为主要原料、三聚氰胺为交联剂,合成了双键封端的交联型水性聚氨酯,再经过原位聚合制备了丙烯酸酯改性水性聚氨酯胶黏剂。利用FTIR、XRD、DLS、DTA、电子拉力机、邵氏硬度计等对材料结构与性能进行了表征。通过调节水性聚氨酯与丙烯酸酯的质量比、三聚氰胺的添加量,对产品性能进行了优化。结果表明,当水性聚氨酯与丙烯酸酯质量比为6∶4、三聚氰胺占水性聚氨酯质量为0.53%时,胶黏剂发生5%质量分数的降解温度可达到312℃,吸水率仅为4.69%,T-型剥离强度为5.3 kN/m。     

固化温度对缓凝黏合剂固化时间和强度的影响

为研究固化温度对缓凝黏合剂固化时间和强度的影响,将缓凝黏合剂在固化温度分别为25、45、65、85 ℃的条件下养护。通过邵氏硬度试验研究了3种缓凝黏合剂在不同固化温度条件下的固化速率,测试了缓凝黏合剂在不同固化温度条件下的拉伸剪切强度、抗折强度和抗压强度。结果表明,固化温度越高,缓凝黏合剂固化时间越短,以25 ℃为基准,45 ℃条件下的固化时间缩短约50 %,45 ℃以上,温度每升高20 ℃,固化时间缩短约10 %;以25 ℃条件下的强度为基准,缓凝黏合剂在不同固化温度条件下拉伸剪切强度的变化率在6 %内,抗折强度的增加率在6 %~45 %,抗压强度的增加率在9 %~50 %。     

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-...     

Nanotailoring of polyurethane adhesive by polyhedral oligomeric silsesquioxane (POSS)

The development and commercialization of nanoparticles such as nanoclays (NCs), carbon nanotubes (CNTs) and polyhedral oligomeric silsesquioxanes (POSS) offers new possibilities to tailor adhesives at the nanoscale. Four types of POSS, with reactive mono-functional groups of isocyanatopropyl, glycidoxypropyl, aminoethyl and non-reactive octaphenyl, were incorporated in concentrations of 1, 3 and 5 wt% into a polyurethane (PU)-based adhesive. Thermo-mechanical bulk properties were studied using dynamic mechanical analysis (DMA). Adhesive properties were characterized in shear and peel modes. Atomic force microscopy (AFM) was used to study the nanoscale morphology. DMA measurements indicated that the neat PU possessed a glass transition temperature (T _g) of ≈ 30°C. The T _g of PU/POSS-glycidoxypropyl nanocomposite adhesive increased gradually with POSS concentration to 50°C for 5 wt%. PU/POSS-octaphenyl nanocomposite adhesive exhibited an increased T _g by 10°C for 5 wt%. The incorporation of POSS-isocyanatopropyl in the PU had no effect on the T _g. With respect to shear properties of POSS-octaphenyl-, POSS-isocyanatopropyl- and POSS-glycidoxypropyl-based PU nanocomposite adhesives, shear strength improved by 230, 178 and 137%, respectively, compared to neat PU. POSS-aminoethyl exhibited lower shear and peel strengths, while POSS-isocyanatopropyl provided the best balance of both higher shear and peel strengths compared to neat PU. It was concluded that the grafted functional group on the POSS and its reactivity with the PU network components were the decisive factors with respect to the thermo-mechanical, morphological and adhesive properties of the resulting nanocomposite adhesives. Consequently, the POSS/polyurethane based nanocomposite adhesives could be tailored for a large range of applications.     

快固型胶粘剂的研制

研制成用聚氨酯丙烯酸树脂 (PUA)改性的室温快固型双组分丙烯酸酯胶粘剂 ,结果表明 ,它对金属的粘接强度高达 12 .5MPa ,最小固化定位时间 2 5s ,伸长率较高 ,对它的储存稳定性也作了改进     

还原纳米石墨/聚氨酯导电胶的制备与性能研究

利用异氰酸酯与多元醇在不同的反应条件下制取三种性能不同的聚氨酯(PU)预聚体(PUⅠ、PUⅡ和PUⅢ),然后分别与还原纳米石墨(RNG)、三羟甲基丙烷(TMP)混合制备三种RNG/PU导电胶(RNG/PUⅠ、RNG/PUⅡ和RNG/PUⅢ)。运用多种检测手段对导电胶的导电性能、力学性能和热稳定性能进行了分析。结果表明:随着RNG质量分数的增加,三种导电胶的导电性能均增强,其导电逾渗阀值分别为10.0%、16.7%和20.0%;导电胶的拉伸剪切强度随RNG质量分数的增加呈先升后降的趋势,当w(RNG)=20%时导电胶的拉伸剪切强度为1.37～4.40MPa;RNG的加入使导电胶的热稳定性能明显提高。     

Synthesis and properties of allyloxyethyl 2-cyanoacrylate adhesive

Allyloxyethyl 2-cyanoacrylate monomer was synthesized and characterized for the first time. It was found that this monomer retains the typical properties of cyanoacrylate adhesives such as fast setting time at room temperature, adhesion to most materials, and high strength of bonded joints. Because of its long ester group and the reactive allyl group, this cyanoacrylate monomer produces adhesive bonds which have improved elasticity and heat resistance. IR and DSC studies showed crosslinking of the adhesive layer when subjected to elevated temperature, which explains the increased tensile shear strength of steel bonded joints. It was found that allyloxyethyl 2-cyanoacrylate can also be used as a crosslinking component for cyanoacrylate adhesives, based on ethyl 2-cyanoacrylate. Less than 10% of allyloxyethyl 2-cyanoacrylate in the mixture is needed for increasing, over three times, the tensile shear strength of the adhesive joint after ageing at 100°C.     

Benchmark tests on adhesive strengths in butt, single and double lap joints and double-cantilever beams

The RC99 committee of the Japan Society for Mechanical Engineers conducted the benchmark tests on strengths of adhesive joints using different testing methods. The effects of joint configuration, loading mode, adherend yield strength and so on, on the strength and data scatter were investigated using two typical epoxy adhesives. The strengths obtained by various tests were compared with each other. The relationships among strengths of butt, single lap and double lap joints and fracture toughness were given. Thirteen member institutes of the committee participated in this project. The benchmark results allow us to recognize that the joint strengths are strongly affected by the curing process. The key to obtaining the appropriate joint strength, is precise temperature control inside the adhesive layer for curing. Toughened adhesives do not always give higher joint strengths than untoughened adhesives. The yield strength of adherends much affects the observed lap joint strength of adhesives.     

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。     

F-992抗蠕变光学结构胶

以改性环氧树脂为主粘料,用反应性端羧基丁腈橡胶（CTBN）为增韧剂,与改性多元胺端氨基聚醚固化剂配制成具有较高交联密度的光学结构胶。因较高的交联密度和使用耐热改性剂,提高了耐热性;CTBN与环氧树脂进行预反应,并加入气相法白炭黑,提高了胶液的贮存稳定性和粘接强度。制备的光学结构胶拉伸剪切强度15．7MPa,压缩剪切强度25．4MPa,常温条件下蠕变值小于2英寸,表现出良好的粘接强度和耐热、耐冲击振动及抗蠕变性。     

Study of Properties of One-Component Moisture-Curable Polyurethane and Silane Modified Polyurethane Adhesives

Abstract

In this paper, the curing behavior and adhesion properties of five kinds of polyurethane (PU) and silane modified polyurethane (SPU) adhesives were studied. Fourier transform infrared spectra showed that the adhesive Sikaflex-555 had an SPU structure and that the other four adhesives were one-component polyurethanes. The experimental results of curing behavior show that the tack-free times and curing rates of these adhesives were significantly affected by the relative humidity and the temperature. The adhesion of the SPU adhesive to glass sheet, zinc galvanized steel sheet and steel sheet was much better than that of PU adhesives. The tack-free times and curing rates of all the adhesives was measured during the 12 months of storage.     

Addition of different amounts of a urethane-based thickener to waterborne polyurethane adhesive

To adjust the rheology of waterborne polyurethane adhesives, different amounts of a hydrophobically modified ethoxylated polyurethane thickener (HEUR) were added. The thickened adhesive solutions were characterized by flow rheology, pH measurements, particle size, solids content and confocal microscopy. The thickened solid adhesive films were characterized by IR spectroscopy, plate-plate rheology, dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The adhesion was measured from T-peel test of plasticized PVC/polyurethane adhesive/plasticized PVC and leather/polyurethane adhesive/SBR rubber joints. The addition of the HEUR thickener increased the viscosity of the polyurethane dispersion, and a shear-thinning behaviour was observed due to polyurethane–thickener interactions. The addition of thickener improved the rheological properties of the polyurethane, more noticeable as the content of the thickener increased. The crosslinking of the thickened polyurethane was studied by confocal microscopy. Although the addition of the thickener did not greatly affect the thermal properties of the polyurethane, an improvement in the adhesive strength of leather/adhesive/SBR rubber joints was obtained.     

新型鞋用不黄变热塑性聚氨酯胶粘剂的研究

介绍了新型鞋用不黄变热塑性聚氨酯胶粘剂的一步法合成工艺,探索出最佳合成工艺条件：聚酯（PBA）与异佛尔酮二异氰酸酯（IPDI）最佳反应时间为5～10min、反应温度为100～115℃、催化剂二月桂酸二丁基锡用量（质量分数）为0．5％、n（-NCO）／n（-OH）为1．03～1．05、后熟化时间为4～10h及后熟化温度为120～140℃;合成出了一种具有结晶度高、结晶速度快、耐热性好、剥离强度高、稳定性好、综合性能优良等特点的新型鞋用不黄变聚氨酯胶粘剂。     

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.     

Influence of wood extractives on two-component polyurethane adhesive for structural hardwood bonding

ABSTRACT

When bonding wood for structural applications, the wood–adhesive bond is influenced by a variety of factors. Besides the physical and mechanical properties of wood species, their chemical composition, e.g. wood extractives, can play a role in bonding wooden surfaces. A two-component polyurethane system (2C PUR) was chosen to better adapt to the current adhesion problem. The influence of extractives on crosslinking was determined by Attenuated Total Reflection-Fourier Transform Infrared Spectrometer (ATR-FTIR) and on the rheological behavior in terms of gel point and storage modulus. Therefore, 2C PUR was mixed with 10% of eight common wood extractives separately. Furthermore, the mechanical properties of beech wood (Fagus sylvatica L.) bonded with extractive enriched adhesive were tested by means of tensile shear strength tests and evaluation of wood failure. These results of ATR-FTIR clearly show that the majority of crosslinking was terminated after 12 hr. Acetic acid and linoleic acid expedited the isocyanate conversion during the first 2.5 hr. The curing in terms of gel point and storage modulus of 2C PUR was accelerated by starch, gallic acid, linoleic acid, and acetic acid. Heptanal, pentanal, 3-carene, and limonene decelerated the curing. All extractives lowered the storage modulus determined after 12 hr. The bonding of beech wood with extractive–adhesive blends showed a slight decrease of the mechanical properties, with the exception of a marginal increase in the case of linoleic acid and pentanal.

In summary, it can be said that 2C PUR is sensitive to the influence of wood extractives and can therefore be partly held responsible for adhesion problems occurring when extractives in surface-wide and higher contents are available.     

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.     

无溶剂型双组分有机硅改性PU胶粘剂的制备与性能研究

以聚醚二元醇(DL-1000)、4,4′-二苯基甲烷二异氰酸酯(MDI)为主要原料合成端-NCO基PU(聚氨酯)预聚体;然后以γ-氨丙基三乙氧基硅烷(KH-550)对其进行嵌段共聚改性,并以3,3′-二氯-4,4′-二氨基二苯基甲烷(MOCA)/蓖麻油作为复合固化剂,制备出无溶剂型双组分有机硅改性PU胶粘剂。研究结果表明:硅烷键已引入PU胶粘剂中;随着KH-550含量的不断增加,胶粘剂的黏度增大、固化时间缩短、室温剪切强度下降且耐热性增强;通过调节不同KH-550含量,可制备出不同性能要求的胶粘剂;该胶粘剂的玻璃化转变温度(-45.9℃)相对较低,说明其耐寒性相对较好。     

Preparation of highly phenol substituted bio-oil–phenol–formaldehyde adhesives with enhanced bonding performance using furfural as crosslinking agent

Highly phenol substituted bio-oil–phenol–formaldehyde (BPF) adhesives were prepared via the phenolization-copolymerization method, in which furfural was used as a novel crosslinking agent to improve the bonding performance. The effects of bio-oil percentage, furfural content, curing temperature, and pressure on the performance of BPF adhesives have been studied in detail. A BPF adhesive with 75% bio-oil percentage and 15% furfural loading (named 75BPF_15) was synthesized, which was cured at 180 °C and 4 MPa. Compared to the conventional phenol–formaldehyde adhesive, the wet tensile strength of 75BPF_15 adhesive reached 2.84 MPa, which was significantly higher than the 1.54 MPa of PF. A possible mechanism of BPF adhesives crosslinked with furfural is proposed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46995.