内置胶囊混凝土的裂缝自愈合行为分析和试验

研究了一种具有裂缝自愈合行为的内置胶囊混凝土.首先,建立了描述修复胶囊在混凝土中的分布和取向函数;然后,根据混凝土的破坏机理,确定了修复胶囊的破坏应力;第三,通过实验分析了修复胶囊的几何参数和体积率对混凝土性能的影响,得到了几何参数和体积率的最佳取值范围;第四,利用ANSYS对修复胶囊进行了有限元分析,确定了其合理的壁厚,为修复胶囊材料的选择提供了一种研究方法;最后,进行了内置胶囊混凝土试验,取得了一定的自愈合效果.     

谐波减速器黏着磨损失效加速寿命模型研究

针对空间润滑谐波减速器黏着磨损失效的加速寿命试验方法问题,首先基于Johnson-Williamson的粗糙表面接触模型建立了混合润滑状态下的黏着磨损模型,模型表明磨损速率主要由粗糙表面微凸体接触承担的载荷比例决定.然后,对磨损部位进行考虑粗糙表面真实形貌与润滑剂流变特性的混合润滑数值分析表明,转速与载荷对微观界面接触与润滑分布状态的影响显著,温度的影响有限,因此传统提高转速并升高温度以保持油膜厚度一致的加速寿命试验方法已不适用.最后以增大转速、载荷并保持或增大混合润滑状态下微凸体接触承担的载荷为加速寿命试验准则,以微凸体承担载荷为加速应力建立了黏着磨损的加速寿命模型,并以不同工况的加速寿命试验与寿命分布统计对其准确性进行了验证.     

高性能超细晶粒金刚石涂层刀具制备及试验研究

采用改进的预处理方法和变参数沉积工艺在硬质合金刀片上制备了超细晶粒金刚石薄膜涂层.通过玻璃纤维增强塑料的车削试验,研究了薄膜与基体之间的附着强度、涂层刀具的磨损和加工工件的表面粗糙度.试验结果表明改进的预处理方法能够有效增强金刚石薄膜与基体之间的附着强度;超细晶粒金刚石薄膜减小了刀具与工件之间的摩擦,降低了刀具磨损,并使加工表面的表面粗糙度显著降低;使用改进预处理方法和变参数沉积工艺制备的超细晶粒金刚石涂层刀具的寿命达到未涂层刀具寿命的8倍以上.     

胶粘剂中挥发性醛类化合物的环境气候箱释放模拟及高效液相色谱检测方法研究

建立了检测胶粘剂施工后13种挥发性醛类化合物释放量的环境气候箱-高效液相色谱(HPLC)法。胶粘剂涂覆于基材上,置于恒温、恒湿的气候箱中,采用2,4-二硝基苯肼(DNPH)吸附管从气候箱采样口进行取样,醛类化合物与DNPH发生化学反应生成稳定的苯腙类衍生物,用乙腈进行淋洗、解吸,定容后进行HPLC分析。采用Kromasil KR100-5 C₁₈色谱柱(250 mm×4.6 mm,5μm)分离,以乙腈-水为流动相在流速1.0 mL/min下进行梯度洗脱,色谱柱温度为40℃,检测波长为360 nm。结果表明:13种醛类化合物在一定质量浓度范围内具有良好的线性关系(r≥0.997 7),检出限(LOD)为1.6～20.8μg/m³,回收率为86.3%～115%,相对标准偏差为3.5%～8.6%。该方法具有良好的准确度和精密度,为粘合剂施工后醛类化合物释放量的检测提供了一种新方法。     

Pressure‐sensitive adhesive utilizing molecular interactions between thymine and adenine

A simple pressure‐sensitive adhesion (PSA) system incorporating noncovalent interaction between thymine and adenine is presented. A copolymer having thymine moieties is combined with a low‐molecular‐weight bifunctional adenine cross‐linker. Molecular interactions caused by multiple hydrogen bonds between the thymine and adenine units are evaluated by FT‐IR spectral measurement. Mechanical properties of the PSA are examined by stress–strain curves and dynamic mechanical analysis. As the number of adenine cross‐linkers increases, Young's modulus increases from 0.24 to 3.0 MPa, and the glass transition temperature increases. Furthermore, it is found that the PSAs have adequate adhesive property from their shear strength test. Heat treatment at 80 °C is effective for reinforcement because of interchange of the hydrogen bonds. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1332‐1338     

Multi-scale studies of glass transition and uniaxial tensile properties of a commercially available epoxy adhesive using experimental measurements and molecular dynamics simulation

In this study, the glass transition and uniaxial tensile properties of a commercially available epoxy adhesive were investigated using experimental measurements and molecular dynamics(MD) simulation. Differential scanning calorimetry(DSC) was used to study the change of glass transition temperature(T g) with cross-link density(CLD). Uniaxial tensile test was performed to measure the Young's modulus(E), Poisson's ratio(ν) and yielding strength(σY). In MD simulation, the complicated epoxy system was simplified as the mixture of two kinds of simple molecules, with the key information well preserved and the less important details omitted. The molecular model of the cross-linked epoxy network was constructed and its mechanical properties were calculated using MD simulation. Overall, the MD simulation results agreed with experimental ones, which proved the validity of the molecular model and justified the simplification method of the industrylevel epoxy system.     

Ginzburg–Landau vortices,Coulomb gases,and Abrikosov lattices

This is a review of a mathematical analysis of vortices in the Ginzburg–Landau model: phase transitions and effective energies that govern optimal patterns formed by the vortices, in particular the Abrikosov lattice, are discussed. Analogies with Coulomb gases are also mentioned.     

耐高温高塑性应变高聚物及其酰亚胺化特征

本文介绍了最近研制成功并用于材料热强度应变测量、耐热300℃、灵敏系数K>1.85和应变极限ε>8％,具有独特力学性能的耐高温高塑性(大)应变胶粘剂。以Ⅳ号胶为代表着重研究了这些溶液型共聚-共混聚酰胺酸在热酰亚胺化为最终产物过程中,各个阶段的特征及对性能的影响。结果发现,急剧酰亚胺化(155℃附近)之后,聚合物的T(>280℃)便已接近最大值,认为继续的酰亚胺化反应至完全(225℃附近)是在软玻璃态中进行的。文中确定了该胶粘剂呈现优良应变特性和粘结性的热-酰亚胺化温度是250—260℃。