Anaerobic Adhesive Cure Mechanism-I

Anaerobic adhesives are single-component acrylic adhesives which cure rapidly at or below room temperature when air is excluded, but they remain in an uncured stage over a long time when they are exposed to an adequate supply of air. Thus, anaerobic adhesives are widely used in retaining compounds for nuts and bolts, in sealants, and for impregnation. Recently, anaerobic adhesives have also been used in electrical and electronic applications because of their fast room temperature cure capability and their convenience.¹     

Anaerobic Adhesive Cure Mechanism-I

Anaerobic adhesives are single-component acrylic adhesives which cure rapidly at or below room temperature when air is excluded, but they remain in an uncured stage over a long time when they are exposed to an adequate supply of air. Thus, anaerobic adhesives are widely used in retaining compounds for nuts and bolts, in sealants, and for impregnation. Recently, anaerobic adhesives have also been used in electrical and electronic applications because of their fast room temperature cure capability and their convenience.¹     

Van Der Waals Attraction Between Macroscopic Bodies

A general dispersion formula is derived, which represents the dispersion energy between two bodies A and B by their macroscopic screened fluctuation fields. These fluctuation fields are calculated exactly in the case of half-spaces and spheres. In the case of half-spaces the Lifshitz dispersion formula is obtained. The dispersion energy between spheres is found to vary as 1/d for separations d small compared with the radii and to be proportional to 1/d ⁶ for separations d large compared with the radii. The effect of layers adsorbed on the surfaces of the spheres on the dispersion energy is calculated. The dielectric properties of the adsorbed layers predominate over those of the bulk material for separations d smaller than the layer thickness.     

厌氧胶粘剂的技术进展

从单体与树脂、固化体系、稳定体系、特殊用途等方面概述了厌氧胶粘剂的技术进展并提出展望。     

测试预涂厌氧胶微胶囊抗渗透性的研究

针对目前市场上双组分水基预涂厌氧胶使用中,由于B组分的渗透导致两组分混合后出现凝胶的现象,提出了快速测试B组分即微胶囊抗渗透性的方法。选择对芯材有良好溶解能力的溶剂作为浸泡液,利用气质联用仪测试渗透出的芯材含量,最终得到微胶囊的渗透曲线。同时通过贮存稳定性试验验证此方法的有效性,结果显示两种方法得到的结果一致。     

耐热树脂对厌氧胶耐热性能影响的研究

在厌氧胶中添加了N,N’-4,4’-二苯甲烷双马来酰亚胺（BDM）和苯乙炔苯酐封端的聚酰亚胺（PBDB-I）,测试了热强度、高温老化强度和热失重,考察了BDM和PBDB-I对厌氧胶的高温力学性能的影响,并借助FT-IR、DSC和SEM分析了耐高温树脂对厌氧胶耐热改性的机理。BDM与厌氧胶单体具有较好的热反应协同性,而PBDB-I与厌氧胶单体的热反应协同性较差,但将BDM与PBDB-I相结合作为耐热树脂可使耐热性大大提高,厌氧胶耐300℃老化的时间可超过60h。     

Polymerization kinetics of acrylonitrile by oxidation: Reduction system using potassium persulfate/ascorbic acid in an aqueous medium

The kinetics of acrylonitrile polymerization initiated by free radicals formed in situ in a potassium persulfate/ascorbic acid redox system was investigated in an aqueous sulfuric acid medium in the temperature range of 40–70°C. The rate of polymerization and the rate of the disappearance of potassium persulfate were measured. A kinetic scheme involving the production of initiating radicals from the oxidation of ascorbic acid by potassium persulfate ions and termination exclusively by the interaction of chain radicals with persulfate ions is proposed. The effects of some water‐miscible organic solvents on the rate of polymerization were investigated. The temperature dependence of the rate was studied. A possible mechanism consistent with the experimental data is proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

硼硅树脂改性厌氧胶黏剂耐热性能研究

采用含有不饱和双键的烷氧基硅烷与硼酸通过直接缩合反应合成了一种硼硅树脂(B-Si resin),采用FTIR、TG对硼硅树脂的结构及耐热稳定性能进行了表征。制备的硼硅树脂的急剧热失重温度可达400℃以上。将硼硅树脂与乙氧化双酚A二甲基丙烯酸酯和间苯撑双马来酰亚胺相匹配制备一种耐高温厌氧胶,该厌氧胶具有良好的耐热稳定性能,在400℃高温下或在400℃老化2h之后,仍具有良好的粘接强度。     

J-671汽车刹车片胶粘剂的研究

介绍了J- 671汽车刹车片胶粘剂的组成、性能、应用 ,并对该胶粘剂的固化机理进行了研究。     

J-166厌氧型螺纹锁固胶的研制

本文介绍了J-166厌氧型螺纹锁固胶的研制和性能,该胶主要用于螺纹连接件的永久性销固和密封.     

Linking Cure Process to Adhesive Bulk Strength by Differential Thermal Analysis

A first order kinetic reaction model is utilized to model the cure process of epoxy adhesive Metlbond 1113. Actual states of full cure corresponding to a spectrum of cure temperature-time schedules are identified using the DTA method. Comparison of these experimental results with the corresponding theoretical predictions reveals that the first order kinetic reaction model provides accurate prediction of full cure when low temperature-long time schedules in close proximity to T_g are used. These cure schedules also result in the highest adhesive bulk tensile strength.     

力矩调节剂对耐高温厌氧胶性能影响的研究

在耐高温厌氧胶中添加了石墨粉末、二硫化钼、聚乙烯粉末和蓖麻油力矩调节剂,测试了厌氧胶的室温强度、热强度和高温老化强度,考察了力矩调节剂对厌氧胶破坏扭矩和平均拆卸扭矩的影响,并借助SEM探讨了力矩调节剂对厌氧胶改性的机理.添加10％的石墨、二硫化钼或聚乙烯粉末只降低厌氧胶的平均拆卸扭矩,而不会降低破坏扭矩.蓖麻油会使厌氧...     

多元共聚丙烯酸酯压敏胶乳液的开发研究

研究了一种多元共聚丙烯酸酯压敏胶乳液,按照半连续乳液聚合法聚合而成,并讨论了软硬单体、功能单体、乳化剂的选择对乳液性能的影响。通过改变预聚单体乳化液数量来调节乳液的粘度以满足不同的涂布工艺的需要。     

聚酰亚胺-环氧树脂胶黏剂的固化动力学研究

以2,2-双[4-(4-氨基苯氧基)苯基1丙烷(BAPOPP)和2,2-双[4-(3,4-二羧基苯氧基)苯基]丙烷二酐(BPADA)为原料在室温下于DMAe溶剂中合成了一种新型聚酰亚胺,并用其改性环氧树脂体系获得聚酰亚胺-环氧体系胶黏剂.利用差示扫描量热计(DSC),以不同的升温速率对聚酰亚胺-环氧树脂胶黏剂进行DSC...     

厌氧胶固化引发剂微胶囊的制备

用原位聚合法制备了以厌氧胶固化引发剂过氧化羟基异丙苯为芯材、脲甲醛树脂为壁材的微胶囊。通过单因素比较法讨论了影响微胶囊制备的几个主要因素。实验表明,制备脲甲醛树脂微胶囊的最佳反应条件为:n(尿素)∶n(甲醛)=1.0∶2.0,壁材与芯材的质量比为10∶3,阿拉伯树胶的质量分数为2.5%,乳化剪切速度为2 000 r/m in,加酸速度为40 m in内把pH降到1.5。实验制备的微胶囊分散性好、粒径分布窄、平均粒径约为100μm。     

厌氧胶粘剂的合成研究

以苯酚、甲醛、丙烯酸为主要原料合成一种厌氧胶,试验对羟甲基酚醇的合成条件、醑化反应的工艺条件和厌氧胶粘剂的配方进行了优化。在原料配比为2．5：1,反应时间为70min,pH值为10,反应温度为75℃时羟甲基酚醇生成量最多;当丙烯酸分批投入,催化剂一次投入,反应时间为2．5h,反应温度为50—60℃时酯的收率较佳;当单体重8．1278g,引发剂、促进剂、助促进剂分别为单体质量的5％、2．8％和1．0％时,胶的调配最佳。     

Kinetics and mechanism of the K2CrO4?NaAsO2 redox‐initiated aqueous polymerization of acrylonitrile

The kinetics and mechanism of acrylonitrile polymerization initiated by a redox pair [potassium chromate (K₂CrO₄) and sodium arsenite (NaAsO₂)] were studied. The overall rate of polymerization was proportional to √[K₂CrO₄] × [NaAsO₂], and the energy of activation was approximately 10.5 kJ/mol. Polyacrylonitrile was recovered as a coagulum in the medium. The formation of polyacrylonitrile was confirmed with Fourier transform infrared and ¹H‐NMR analyses. Scanning electron microscopy analysis of the polymer revealed the formation of aggregates of polymer particles (3–67 nm). Thermogravimetric studies indicated 50% weight loss at 400°C, and dynamic thermal analysis scan studies revealed an exothermic peak at 507°C due to massive oxidative thermal degradation of the polyacrylonitrile backbone. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 276–280, 2005     

Reply to Comment on “Linking Cure Process to Adhesive Bulk Strength by Differential Thermal Analysis”

A Comment published in this issue and authored by B. C. Ennis refers extensively to one of our earlier papers entitled “Linking Cure Process to Adhesive Bulk Strength by Differential Thermal Analysis.” We are delighted to see that our work can capture the attention of scientists working in this area and stimulate them to write lengthy reviews. At the same time, however, we feel that this particular note, in various discussions, misinterprets our paper, and does not seem to contribute any new or substantial scientific information to the literature.     

Cure properties of epoxies with varying chain length as studied by DSC

The cure of diglycidyl ether of bisphenol A (DGEBA) and a homologous series of poly(ethylene oxide) diglycidyl ether (PEODE) epoxy resins with 4,4′‐diaminodiphenyl sulfone (DDS) was studied by scanning and isothermal differential scanning calorimetry (DSC). The heat of polymerization was relatively independent of monomer structure and chain length when determined by isothermal DSC. Variations in the heats of polymerization determined by the scanning method were attributed to degradative reactions at higher temperatures during the scan. The activation energies determined by scanning DSC experiments were relatively constant at 61 ± 3 kJ/mol. However, using an isothermal cure method, the activation energies were found to vary with monomer structure and extent of cure. The isothermal kinetics were analyzed in terms of the autocatalytic model on the basis of competing reaction paths involving catalysis by either initial impurities or hydroxyl groups produced in situ. The activation energies of both reaction paths were found to vary with monomer structure and degree of conversion. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1479–1488, 1999     

新型酚醛树脂固化反应动力学及固化机理研究

采用DSC热分析对S酚醛树脂的固化过程进行了动力学研究,得出了该树脂的固化工艺温度及固化动力学参数,其凝胶化温度、固化温度和后处理温度分别为360.7K、421.6K和463.4K;反应级数n=0.912、表观活化能E=76.14kJ·mol^-1,反应频率因子A=4.704×10^8min^-1。采用红外光谱分析初步探讨了该树脂的固化机理,结果表明其固化反应主要是苄羟基与苯环邻位上活泼氢产生交联缩合反应,少量为苄羟基之间的缩合反应。