二氧化硅对不饱和聚酯树脂浇铸体力学性能的影响

研究了SiO2对不饱和聚酯树脂（UPR）浇铸体拉伸性能的影响．用应变计电测法研究了SiO2填料对树脂浇铸体的拉伸变形特性和弹性模量的作用．运用变形功原理，对添加SiO2后材料的特性作了初步判断。结果表明：在所采取的实验条件下．填料SiO2的添加量对UPR的拉伸强度和弹性模量有显著的影响．其质量分数为8％时得到的强度比纯树脂试样提高了大约4．1％．但SiO2质量分数为8％时却是对应着材料的脆韧转变点。     

纳米SiO2对甲基乙烯基硅橡胶结构和性能的影响

采用沉淀法和气相法纳米SiO2补强硅橡胶,考察纳米SiO2的添加量和比表面积对结合橡胶量、橡胶吸附层厚度以及硅橡胶补强力学性能的影响．通过溶胀平衡实验计算填料补强能力参数C值,并通过扫描电镜观察填料纳米SiO2在硅橡胶中的分散状态．结果表明：填料添加量对硅橡胶力学性能的影响效果显著,当质量比为0．4时,补强橡胶具有较好的力学综合性能,结合橡胶量增大至49．24％,吸附层厚度增至6．87nm,对于气相法纳米SiO2,增大填料比表面积有利于提高结合橡胶量,改善填料的补强效果,补强硅橡胶热稳定性也相应提高,此外填料的C值也随之增大,选一步验证了填料的补强效果增强．     

SiO2添加量对XH-11胶线膨胀系数的影响

研究了经硅烷偶联剂处理的市售SiO2粉添加量对XH-11环氧胶线膨胀系数的影响，结果表明，所添加的SiO2粉填料与胶粘剂的配比达0．75时，在剪切强度与无填料的接头相当情况下，其线膨胀系数降低了约1／3，对于降低接头中的温差热应力有明显的作用。     

填料改性对胶接应力影响的仿真研究

利用弹塑性有限元法,研究了三种填料改性的不同弹性模量的环氧胶粘剂对铝合金单搭接胶接应力的影响.研究结果表明:碳化硅对环氧胶粘剂的弹性模量提高较大,碳酸钙对环氧胶粘剂的线膨胀系数降低较多;接头应力在沿搭接长度方向基本呈对称分布,在胶接边缘的位置出现峰值,胶层中部应力较小;随着弹性模量的增加,接头的应力峰值逐渐增大;填料改...     

CaCO3对UPR浇铸体拉伸性能的影响

研究了CaCO3填料对不饱和聚酯树脂（UPR）浇铸体拉伸强度的影响，借助于应变片电测技术研究了CaCO3填料对树脂浇铸体的拉伸变形特性和弹性模量的作用。结果表明：在所毒取的实验条件下，填料CaCO3的添加量对UPR的拉伸强度和弹性模量有显著的影响，添加量为8％（质量分数）时试样的强度比纯树脂提高了大约54％，分析了填料CaCO3提高UPR拉伸强度的原因在于其显著提高了材料的韧性。     

KH-550改性纳米SiO2对环氧胶黏剂性能的影响

制备了氨基硅烷偶联剂（KH-550）表面接枝改性纳米SiO2粒子,利用正交实验,讨论了改性剂用量、改性温度以及改性时间对活化指数的影响。并将KH-550硅烷偶联剂包覆纳米SiO2作为填料,以环氧树脂E-44为基体,制备环氧树脂胶黏剂,通过对胶黏剂进行剪切强度,扫描电镜和阻抗测试,研究了改性纳米SiO2对环氧胶黏剂粘结性能以及耐蚀性能的影响。结果表明：改性纳米SiO2填充的环氧胶黏剂的剪切强度得到提高,最大增幅达到2MPa,耐蚀性能也得到提高。     

氟化石墨烯/水滑石改性环氧树脂胶黏剂的性能研究

采用尿素法制备CO3^2-型锌铝水滑石(ZnAlCO3-LDH),并将其与氟化石墨烯(FG)复合,制备不同质量比的FG-ZnAl-LDH,然后将其作为填料对环氧胶黏剂进行改性。通过红外光谱、X射线衍射和扫描电镜对填料进行表征,同时,研究填料添加量及质量比(FG∶LDH)对环氧树脂胶黏剂黏接性能、疏水性能和热稳定性能的影响规律。结果表明,采用尿素法制备的LDH及FG-ZnAl-LDH为二维片层结构,LDH特征峰强度随FG比例增加而逐渐降低。填料添加量为2%,FG∶LDH=1∶1时,FG-ZnAl-LDH改性环氧树脂胶黏剂的性能最佳,其剪切强度较改性前提高26.32%,水接触角提高32.9%,热分解温度提高约5℃。研究表明氟化石墨烯/水滑石的添加,可在环氧树脂胶黏剂中起到增强效果,其不仅可以提高胶黏剂的黏接强度,而且对胶黏剂的疏水性和热稳定性也具有显著的提升作用。     

纳米SiO2填料对离子凝胶电解质及高压超级电容器性能的影响

以SiO2纳米颗粒为填料,通过溶液浇筑法合成了纳米复合离子凝胶电解质,研究了SiO2填料对离子输运的影响规律。基于离子凝胶电解质构筑了准固态电容器,探讨了无机填料对电容器性能的影响,以活性炭为电极、凝胶电解质为隔膜,构筑了准固态双电层电容器。结果表明,SiO2的加入没有改变隔膜电解质的微观形貌,但有效改善了浸润性,提高了离子电导率。高SiO2添加量的隔膜电解质电化学性能更优,当添加8wt% SiO2时凝胶电解质电化学性能最优。SiO2的加入可有效提高活性炭准固态电容器的性能,电容器的比容提升约15%,经4000次循环后容量保持可达100%。电解质高温稳定性良好,器件最高使用温度可达60℃。基于该复合电解质构筑的电容器具有良好的高温性能,电容器比容随温度升高而逐渐提升,60℃时能量密度可达81.36 Wh/kg。     

可见光固化齿科充填复合树脂挠曲强度研究

以气相SiO2作为无机填料,从树脂基质和填料两个方面研究了可见光固化齿科用复合树脂的挠曲强度。详细探讨了树脂基质中环氧丙烯酸树脂与活性稀释剂的配比、填料含量、偶联剂对填料的处理等因素对复合树脂挠曲强度的影响。结果表明,对于纳米级的SiO2填料,当树脂基质体系的粘度较低时,复合树脂的挠曲强度较高;当SiO2的质量分数为25％并经偶联剂处理后,复合树脂挠曲强度最大,达到84．80MPa。     

EP/POSS/SiO2纳米复合材料性能研究

以自制的两种不同黏度的环氧基倍半硅氧烷(POSS)为改性剂,对双酚A型环氧树脂(EP)/4,4’–二氨基二苯砜(DDS)进行改性,制备EP/POSS杂化材料。再以纳米SiO2为填料制备了EP/POSS/SiO2纳米复合材料。结果表明,与EP相比,杂化材料和纳米复合材料的弯曲强度和弯曲弹性模量都有所提高,其中纳米复合材料(分别添加低黏度和高黏度的POSS)的弯曲弹性模量分别提高了15.03%和9.44%,添加高黏度的POSS和纳米SiO2后其杂化材料和纳米复合材料体系的弯曲强度均有所提高,杂化材料和纳米复合材料的最大分解温度和在高温时的热残留量都有所提高。     

Effects of Bonding Layer Characteristics on Strain Transmission and Bond Fatigue Performance

Abstract

Fiber Bragg Grating (FBG) sensor arrays can be used to monitor the mechanical behavior of large composite structures. However, brittle FBG sensors, especially multiplexed FBG sensors can be easily damaged when they are installed in flexible structures. As a protection for brittle FBG sensors, epoxy packaged FBG sensors have been suggested. Packaged FBG sensors are usually installed using epoxy adhesives onto the composite specimen since they have high mechanical, heat-resistance and insulation properties. However, the adhesive could decrease strain transmission from the bonding layer and suffer from aging problem. In this paper, strain transmission and bond fatigue performance of the bonding layer depending on the elastic modulus of adhesive, elastic modulus of packaging material and bonding layer thickness are discussed. Static tests were performed to evaluate the effects of bonding layer thickness and elastic modulus ratio of adhesive to the packaging material on strain transmission. Fatigue tests were performed to evaluate the bond fatigue performance depending on the elastic modulus of the adhesive and bonding layer thickness. It was observed that thin bonding layer with high elastic modulus gave high strain transmission, however, it suffered from debonding problem. The elastic modulus ratio and the bonding layer thickness resulting in high strain transmission while maintaining a long bond fatigue life were found in this study.     

Thermal characteristics of tubular single lap adhesive joints under axial loads

When an adhesive joint is exposed to high environmental temperature, the tensile load capability of the adhesive joint decreases because both the elastic modulus and failure strength of the adhesive decrease. The thermo-mechanical properties of a structural adhesive can be improved by addition of fillers to the adhesive. In this paper, the elastic modulus and failure strength of adhesives as well as the tensile load capability of tubular single lap adhesive joints were experimentally and theoretically investigated with respect to the volume fraction of filler (alumina) and the environmental temperature. Also the tensile modulus of the filler containing epoxy adhesive was predicted using a new equation which considers filler shape, filler content, and environmental temperature. The tensile load capability of the adhesive joint was predicted by using the effective strain obtained from the finite element analysis and a new failure model, from which the relation between the bond length and the crack length was developed with respect to the volume fraction of filler.     

低模量硫化硅橡胶粘接研究

采用sol—gel工艺自制的SiO2补强增韧环氧树脂作为胶粘剂,对低模量硫化硅橡胶与金属或复合材料进行粘接试验,分析胶粘剂中SiO2理论含量及粘接工艺对粘接性能的影响,并把硫化硅橡胶放在改性环氧树脂中进行溶张试验,探索胶粘剂对硅橡胶的粘接机理、结果表明,随着SiO2先驱体-有机硅烷含量的增加,硅橡胶的溶胀程度提高改性环氧树脂胶粘刺能浸入硅橡胶的表层,对硅橡胶具有良好的亲和力。用该胶粘剂对硅橡胶与金属或复合材料进行粘接时,取得了良好的粘接效果。     

A new evaluation procedure for the butt-joint test of adhesive technology: Determination of the complete set of linear elastic constants

Simple analytical formulae have been reported in literature to extract basic elastic material properties of adhesives subjected to tensile loading. The assumptions and simplifications of classical evaluation procedures may result in a remarkable error depending on the investigated material combination. This work proposes a new evaluation procedure for the butt-joint test of adhesive technology. The main idea is to determine the deformed shape of the adhesive layer and to relate the deformation, i.e. contraction and elongation, to a unique set of Young's modulus and Poisson's ratio. A numerical parameter study for different combinations of adherend/adhesive materials and butt-joint geometries has been performed to investigate the influence of these parameters on the adhesive deformation. Comprehensive diagrams are derived which relate the deformation of the adhesive layer to the complete set of linear elastic constants.     

填料对耐高温厌氧胶油面黏接性影响研究

以乙氧化双酚A二甲基丙烯酸酯、环氧丙烯酸酯和三羟甲基丙烷三甲基丙烯酸酯为主要原料,分别采用SiO2、nCaCO3、有机膨润土为无机填料制成耐高温厌氧胶,研究了填料对耐高温厌氧胶油面黏接性的影响。结果表明:填料吸油量的大小影响厌氧胶的油面黏接性,当w(SiO2)=4%~6%时,油面黏接强度损失最小,耐高温厌氧胶的油面黏接性较优。     

Parametric study of factors affecting the pull-out strength of steel rods bonded into precast concrete panels

This paper deals with the effect of bond thickness, embedment length and type of epoxy adhesive formulation on the adhesion of steel anchors to concrete. The test results indicate that the shear strength of the epoxy adhesive formulation prepared from a diglycidylether of bisphenol A (DGEBA) and an ethyleneamine curing agent is independent of bond thickness from approximately 1–4 mm. However, the same is not found to be true for the DGEBA epoxy resin cured using an alkylenediamine curing agent where considerably more complex behaviour is observed. The adhesive shear strength of this system is shown to pass through a maximum value at 2 mm bond thickness. At thickness beyond 2 mm, the strength undergoes a reduction until a value is reached which remains essentially constant with increased thickness. The variation in concrete strength is regarded as a main factor responsible for this complexity. The addition of filler to epoxy adhesive formulations results in a reduction in the adhesive shear strength, the magnitude of the decline being largely dependent upon the quantity of filler used in the mixture. The quadratic equations reviewed in this study provide a basis for assessing trends in the mechanical behaviour of filled epoxy systems. The shear strength of an epoxy adhesive anchor can be determined by an elastic behavioural model. The curves for epoxy adhesives indicate that the elastic solution does fit the experimental data very well. Increasing embedment of an anchor beyond a certain point does not increase the ultimate tension capacity of the anchor.     

The Effect of Viscoelasticity of Polymeric Adhesives on Shear Stress Distribution in a Single-Lap Joint

In this paper, the effect of viscoelasticity of adhesives on shear stress distribution in the adhesive layer of a single-lap joint under shear load is studied. The joint comprises two elastic single isotropic adherend layers joined by a viscoelastic adhesive polymer. A three-parameter viscoelastic solid model is used to deduce the governing differential equation in the Laplace domain, which is solved using residue theorem. Results show that for an impulse load of 100 N, the maximum shear stress in the adhesive layer is reduced to 39% of its initial value. Also, the ratio of viscous modulus of the adhesive to its shear modulus has an adverse effect on the peak shear stress. An increase in the thickness of the adhesive layer reduced the induced peak shear stress in the joint. Moreover, the shear strain in the adhesive layer reached its steady value after 1000 seconds.     

Effects of adhesive fillers on the strength of tubular single lap adhesive joints

When an adhesively bonded joint is exposed to a high environmental temperature, the tensile load capability of the adhesively bonded joint decreases because the elastic modulus and failure strength of the adhesive decrease. In this paper, the elastic modulus and failure strength of the adhesive as well as the tensile load capability of the tubular single lap adhesively bonded joint were experimentally and theoretically investigated with respect to the volume fraction of filler and the environmental temperature. Two types of fillers - Al₂O₃ (alumina) and chopped fiber E glass - were used. From the experiment, it was found that the elastic modulus and failure strength of the adhesive increased in accordance with the increase of volume fraction of the filler and decreased with the environmental temperature rise. It was also found that the tensile load capability of the tubular single lap adhesively bonded joint decreased as the environmental temperature increased; however, it had no correlation with the volume fraction of filler because of the effect of the fabrication thermal residual stresses generated by the CTE difference between the adherend and adhesive.