单向Cf/SiC复合材料的弯曲疲劳性能

对单向Cf/SiC复合材料进行了三点弯曲疲劳性能测试,得到了复合材料的应力－寿命曲线（S－N曲线）,并对其进行线性拟合,得到疲劳最大应力与复合材料疲劳寿命的关系;考察了疲劳过程中刚度下降和疲劳裂纹产生情况。结果表明在疲劳过程中复合材料的弯曲模量有3个变化阶段：首先在疲劳加载初期,弯曲模量的下降速度及幅度都较大;其次在弯曲模量下降到原始弯曲模量的85％（133GPa)后,其变化方式没有明显的规律可循,有时甚至可能上升;最后复合材料发生疲劳断裂时,模量将发生突变。显微结构分析表明：基体横向裂纹群的产生是疲劳断裂的独有特征。它的产生是由于基体SiC的断裂应变小于碳纤维的断裂应变,基体首先开裂并导致应力重新分布的结果。     

稀土丁异戊橡胶改性天然橡胶的应用研究

采用稀土丁异戊橡胶代替顺丁橡胶，测试并分析了改性天然橡胶的低温性能及相关性能。结果表明，稀土丁异戊橡胶改性的天然橡胶室强力学性能和粘接性能与顺丁橡胶改性的天然橡胶相近，但低温性能有较大的改善。在-40℃下贮存2h后，顶丁橡胶改性天然橡胶硫化胶有明显的结晶现象，其剪切模量较室温下的相应值增加了6倍，而稀土丁异戊橡胶改性的天然橡胶硫化胶保持了良好的弹性，其剪切模量值与室温下的相当。     

Failure load prediction of structural adhesive joints : Part 2: Experimental study

The objective of this study was to determine how the fracture of adhesive joints depends on elastic beam parameters describing the adherends and the applied loads. The basic specimen geometry was the cracked lap shear joint constructed of aluminium alloy with various adherend and bondline thicknesses. Loads were applied in different combinations of bending, tension and shear to generate a failure envelope for each adhesive and specimen geometry. It was found that crack propagation for precracked specimens occured at a critical strain energy release rate but was also a function of the G_I/G_II ratio and the bondline thickness. The experiments also showed that the loads required to propagate a crack in a precracked specimen were always lower than the loads required to break the fillet. Hence, by treating uncracked joints as being cracked, where the fictitious crack tip is assumed to coincide with the location of the fillet, a conservative estimate of the failure load is obtained.     

Shear Strength of Pressure Sensitive Adhesives and its Correlation to Mechanical Properties

Correlations between shear resistance and the mechanical properties of pressure sensitive adhesives are studied by measuring the deformation behaviour in the static and the dynamic shear test and determining the dynamic shear modulus of the adhesive. For polymers with low or moderate viscosities, the shear strain vs. time characteristics in a static shear test and, accordingly, the static shear strength, can be evaluated from the master curves of the dynamic shear modulus or the dynamic viscosity. The dynamic shear strength also can be calculated. These exact calculations cannot be applied to highly viscous or slightly crosslinked polymers. On the basis of the model experiments, empirical correlations between shear strength and the dynamic shear modulus are established which seem to be generally valid.     

纳米蒙脱土/环氧树脂胶粘剂制备工艺优化选择

介绍了制备纳米蒙脱土/环氧树脂胶粘剂的方法,并通过正交试验的方法分析了固化时间、固化温度、搅拌时间、搅拌温度对纳米蒙脱土/环氧树脂胶粘涂层拉伸剪切强度的影响,给出了上述四个工艺参数的最佳工艺规范并通过试验验证了结论。     

保护胶体稳定的丙烯酸酯乳液流变性

分别采用常规乳化剂和羟乙基纤维素为保护胶体制备丙烯酸酯乳液。通过TEM分别观察乳胶粒的形态。利用流变仪测定剪切速率（Ds）-剪切应力（τ）关系、剪切速率（Ds）-黏度（η）关系。结果表明：采用羟乙基纤维素为保护胶体制备的乳液与常规乳液具有不同结构，该结构使其乳液体系流变性能不同。在相同剪切速率下，保护胶体制备的丙烯酸酯乳液的剪切力明显大于常规乳液的剪切力，该乳液在一定剪切速率范围内有剪切稀化现象。     

染料释放化合物及一当量成色剂浅谈

简述了染料释放化合物的发展过程 ,并由此引出一当量成色剂的概念 ,叙述了一当量成色剂应用和发展 ,对一当量成色剂应用前景做了预测。     

Shear rate dependence of viscosity and first normal stress difference of LCP/PET blends at solid and molten states of LCP

The liquid crystalline polymer (LCP) and polyethylene terephthalate (PET) were blended in an elastic melt extruder to make samples having 20, 40, 60, 80, and 100 wt % of LCP. Morphology of these samples was studied using scanning electron microscopy. The steady state shear viscosity (η), dynamic complex viscosity (η*) and first normal stress difference (N₁) were evaluated and compared at two temperatures: 265°C, at which LCP was in solid state, and 285°C, at which LCP was in molten state. The PET was in molten state at both the temperatures. The shear viscosity of the studied blends displayed its dependence on composition and shear rate. A maxima was observed in viscosity versus composition plot corresponding to 80/20 LCP/PET blend. The N₁ increased with LCP loading in PET and with the increased asymmetry of LCP droplets. The N₁ also varied with the shear stress in two stages; the first stage demonstrated elastic deformation, whereas second stage displayed dominant plastic deformation of LCP droplets. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2212–2218, 2007     

模数对无机富锌涂料和涂层性能的影响

硅酸钾富锌涂料是目前广泛使用的钢铁防腐蚀涂料。作为涂料粘结剂的高模数硅酸钾溶液对涂料和涂层的性能有重要影响。本研究考察了硅酸钾粘结剂的模数变化对涂料及涂层性能产生的影响。实验结果表明：粘结剂模数的提高可以提高固化后涂层的耐水性能，当粘结剂模数在5.0左右时，所得富锌涂层具有最佳的耐磨性能，但当粘结剂模数超过5.5时会造成涂料施工性能和贮存稳定性下降，涂层柔韧性降低，从而降低涂层的耐磨性能。     

考虑土体强度参数深度依赖性的非平稳随机场边坡滑动深度和体积分析

基于随机有限元方法（RFEM）和Monte-Carlo模拟,建立了能够模拟具有深度依赖性的土体强度参数边坡或具有软弱夹层边坡的非平稳随机场模型。通过辐射扫描方法获取最危险滑动面,得到非平稳随机场边坡滑动深度和滑动体积。将该方法与均质边坡和平稳随机场边坡获得的滑动深度和滑动体积进行对比,研究土体强度参数深度依赖性的非平稳随机场边坡的不同坡度和各向异性对滑动深度和滑动体积的影响。结果表明：基于RFEM的非平稳随机场滑动深度和滑动体积结果为地质灾害风险及后果评估提供了一个参考分析的新角度;参数的深度依赖性程度越高(变化率b越大),则边坡平均滑动深度和滑动体积越小;在大坡度滑坡风险后果评估中,可以基于均质边坡分析结果进行初步预估;在非平稳随机场中,随着各向异性的增大,所有坡度边坡的滑动体积变异系数增大;不同坡度下,水平方向的相关程度越大,则土坡内软弱夹层的不确定性越强,滑动体积的变异系数也不断增大。