原位聚合法制备厌氧胶固化引发剂微胶囊

采用原位聚合法制备了以脲醛树脂为壁材、过氧化苯甲酰为芯材的厌氧胶固化引发剂微胶囊。研究了乳化剂聚丙烯酸钠、十二烷基苯磺酸钠、阿拉伯树胶、苯乙烯-马来酸酐共聚物的单独使用及阿拉伯树胶与苯乙烯-马来酸酐共聚物的复配组合和其它工艺条件对微胶囊制备的影响;运用FT-IR、TG和SEM等测试技术对微胶囊进行了表征。结果表明,以苯乙烯-马来酸酐共聚物和阿拉伯树胶作为复合乳化剂,反应终点pH值为1.5左右,反应温度70℃,反应时间4 h,搅拌速率1 000 r/m in,可制得分散适中、形貌较好、粒径约为100μm的微胶囊。以实验制备的微胶囊配制成可预涂厌氧胶胶液,性能可以达到国外公司同类产品的技术指标。     

Tack properties of pressure‐sensitive adhesives

Relevant experiments are essential to clearly understand the role of various molecular (chemical structure, surface energy, composition), experimental (contact time, contact pressure, temperature) or topological (sample roughness and thickness) parameters, on the tack properties of pressure sensitive adhesives (PSA). The “mechano‐optical tack tester” (MOTT) is a novel device that we have developed to provide accurate measurements of both the contact area and the tack strength. The MOTT is designed to apply controlled contact pressures by mean of a quartz prism probe, for determined contact times, onto the surface of PSA samples. The probe is then pulled up at controlled rates while the tearing force (tack strength) and the contact area are plotted versus time. The tack energy is then calculated. Using the MOTT, the influence of various parameters (contact pressure, contact area, sample thickness, …) on the tack properties of PSA samples has been studied. The main result lies in the strong dependence of the tack energy on the sample thickness. This points out that the release energy is close to the interface rather than in the bulk of the PSA films, and is a function of the contact area. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1201–1208, 2000     

Identification of Dynamic (Young’s and Shear) Moduli of a Structural Adhesive Using Modal Based Direct Model Updating Method

In this paper, mechanical characteristics (Young’s modulus and shear modulus) of an adhesive are identified using modal based direct model updating method and experimental modal data. The results show that both Young’s and shear moduli of adhesive are frequency dependent. Also, it is demonstrated that the thickness and length of the adhesive-line have influence on these properties. All experiments and subsequent identifications are conducted both in bending and shear modes, and it has been shown that the shear modulus of adhesive is more sensitive to length and thickness variations. The repeatability and consistency of method is proved through repeating the process several times and with different adherends.     

非组分黏接剂对纸基摩擦材料摩擦磨损性能的影响

为了研究黏接剂对纸基摩擦材料摩擦磨损性能的影响,以改性酚醛树脂作为黏接剂,通过高精度天平测定涂胶量,由平板硫化机固定黏接压力得到不同涂胶量的试样.利用光学显微镜观察黏接剂的渗透情况,通过惯量摩擦试验机研究涂胶量对纸基摩擦材料摩擦磨损性能的影响.试验结果表明:随着单位面积涂胶最的增加,黏接剂渗入摩擦材料的深度逐渐增大,对于厚度不大于1.0 mm的纸基摩擦材料,黏接剂可渗透材料并影响其摩擦磨损性能.随着渗透至摩擦面胶量的增加,摩擦材料的制动平稳性逐渐变差,动摩擦系数降低,静摩擦系数升高,磨损率先减小后增大.     

复合材料胶接结构有限元分析方法研究进展

胶接结构的强度分析方法可以分为解析法和数值法两类,数值法主要是有限元方法.本文综述了复合材料胶接结构的有限元分析方法,按照胶接结构有限元模型建立的物理机理,将胶接结构力学分析模型分为基于有限元应力分析模型、基于断裂力学模型和基于损伤力学模型3类.详细介绍了这3类模型中的主要有限元建模分析方法:三维应力分析方法、虚拟裂纹闭合技术方法和内聚力模型方法,介绍了每种方法的基本思想、适用范围、优缺点、改进和扩展、有限元建模的实施步骤,以及有限元分析中应用该方法所取得的成果.第五部分从适用范围、应力奇异和破坏判据3个方面对这几种分析模型进行了对比分析.最后,对该领域发展趋势进行了展望.      

Cr/Ag纳米多层薄膜膜-基结合强度及摩擦学性能研究

采用中频磁控溅射技术在AISI 440C钢表面制备了不同调制周期的Cr/Ag纳米多层薄膜.通过X射线衍射仪（XRD）及高分辨透射电子显微镜（HRTEM）分析表征了纳米多层薄膜的微观组织结构,通过划痕试验机与真空球-盘摩擦试验机分别测试了纳米多层薄膜膜-基结合强度及真空摩擦学性能,并与纯Ag薄膜及Cr/Ag双层薄膜进行了对比.结果表明：纳米多层结构可以显著提高Ag基固体润滑薄膜膜-基结合强度,Cr/Ag纳米多层薄膜在较高转速及载荷条件下表现出明显优于纯Ag及Cr/Ag双层薄膜的摩擦学性能.Cr薄膜层与钢基体表面良好结合以及纳米多层薄膜内良好的层间结合性能是纳米多层薄膜膜-基结合强度提高的主要原因.     

含胶接缺陷的椭球泡沫夹层结构破坏机理与承载能力研究

采用试验和有限元方法,对含胶接缺陷的椭球泡沫夹层结构在外压作用下的破坏模式和承载能力进行了研究。针对国内在研的大尺寸椭球泡沫夹层结构,实施了全尺寸静力外压试验,发现初始胶接缺陷破坏了夹层结构界面应力传递的连续性;随着载荷增加,面板发生皱褶且脱胶界面继续扩展,从而降低结构整体承载能力。通过红外无损检测确定了缺陷的类型和形貌;采用预留相应初始脱粘面积、脱粘间隙以及内聚力单元模拟界面脱粘的有限元分析方法,对含胶接缺陷的椭球泡沫夹层结构承载能力进行预测。数值结果表明:含胶接缺陷结构易发生面板皱褶,且结构顶部和根部区域较易发生界面脱粘扩展。数值和试验结果取得了较好的一致性,本文结果可为同类结构设计提供参考。     

粘接剂对钛合金异质自冲铆接头力学性能的影响

为了研究粘接剂对自冲铆接头性能的影响,分别以TA1-5052和TA1-Q215的单搭自冲铆接头及粘接-自冲铆复合接头为研究对象,采用剖面直观检测法分析接头成形质量,基于静力学试验研究各组接头的静力学性能及失效形式。结果表明:与自冲铆接头相比,复合接头的钉脚张开度和残余底厚值减小;粘接剂对TA1-5052单搭自冲铆接头失效形式无影响,但改变了TA1-Q215单搭自冲铆接头的失效形式;复合接头的静力学性能比自冲铆接头更优;相对于自冲铆接头,TA1-5052复合接头静失效载荷增加了17.5%,能量吸收值增加了13.3%;TA1-Q215复合接头静失效载荷增加了6.8%,能量吸收值增加了25.8%。     

基于贻贝启发的水下仿生胶黏剂

海洋中的贻贝依靠丝足(Byssus)与足盘(Plaque)可以在潮湿及水下环境中快速而牢固地黏附于各种固体表面。贻贝强健的足部具有沟渠状的生理结构,通过类似于“注塑生产”的生理过程,它们可以生成丝足与足盘。贻贝将液态的蛋白质挤压到沟渠里,只需几秒钟时间,这些蛋白质就能形成一条条发丝一样纤细的丝足。每条丝足的末端都有一个黏性足盘,足盘可以牢牢地黏附在岩石及固体表面。丝足及足盘由多种黏附蛋白(Mfps)组成,且几乎每种黏附蛋白都含有L-3,4-二羟基苯丙氨酸(DOPA)成分。在过去的数十年间,科研人员基本揭示了贻贝黏附蛋白的结构及其黏附机理。DOPA的儿茶酚基团,通过氧化交联、金属螯合、氢键、静电作用、疏水作用、π-π作用、阳离子-π作用等各种共价和非共价相互作用,实现强大的界面黏接。基于贻贝黏附蛋白的结构及其黏附机理,通过使用DOPA及其类似物修饰的聚合物体系,人们得到了多种具有优秀机械性能和功能化的新型仿生多巴类水下胶黏剂。本综述首先介绍了贻贝黏附蛋白的组成特点及其黏附机理;随后分别介绍了凝聚层类胶黏剂、水凝胶类胶黏剂、智能型水下胶黏剂的结构特点及黏附机理;最后讨论了目前仿生水下胶黏剂存在的问题及未来发展前景。     

High thermal conductivity EP adhesive based on the GO/EP interface optimized by TDI

Graphene oxide (GO) was used as the filler to modify the epoxy resin (EP) adhesive, and the GO/EP interface was optimized by toluene diisocyanate (TDI) in order to improve the thermal conductivity and T peel strength performance of the adhesive. Through the characterization of the GO product, which was modified by TDI, TDI was grafted onto the surface of GO, and there were NCO groups remaining; thus the chemical bonds were built onto the interface which was non‐wetting between GO and EP. The results of the properties characterization of the adhesive indicated that the bonding properties were significantly enhanced, especially the T peel strength, which was up to 9.62 N/mm, which was contributed by the optimized GO/EP interface. The thermal conductivity of the adhesive increased to 0.624 W m^?1 K^?1, as the interface thermal resistance was reduced after the interface between GO/EP was optimized by TDI. The insulation performance of the adhesive was also improved, since the well‐dispersed GO formed a micro‐capacitance model in EP, and the surface of GO was covered by the EP so that the electronic paths were blocked by the formed chemical bonds.