聚苯硫醚／石墨基双极板复合材料性能的研究

以聚苯硫醚树脂和人造石墨为原料一次模压成型制备双极板复合材料.研究了模压成型过程中加压时机、冷却方式及人造石墨原料对复合材料电导率和弯曲强度的影响.结果表明,制备聚苯硫醚/石墨基双极板材料宜选用石墨化程度较高且结构密实的石墨粉料;采用保温后加压及空气中冷却方式制备的复合材料的综合性能较优.     

Na离子和Cl离子引起He原子直接多重电离过程的研究

利用2～8 MeV的Naq+、Clq+(q=2,3,4,5)轰击氦原子,对碰撞的直接多重电离过程进行研究.实验采用反冲离子-散射离子飞行时间符合技术,通过反冲离子飞行时间谱区分不同价态反冲离子;利用静电偏转和位置灵敏探测技术区分不同电荷态散射离子;结合CAMAC-PC多参数获取系统得到一定价态散射离子所对应的反冲离子电荷态分布谱;经分析该谱得到直接多重电离截面与直接单电离截面之比R21.讨论了R21随入射离子速度和电荷态的变化关系.     

一类广义Lanchester模型的数值解及若干结论

本讨论了一类广义的Lanchester模型在一些限制条件下的近似解，并给出了若干结论。     

普通物理实验教学在重建认知结构中的特殊作用

运用教育学和心理学知识，通过典型的普通物理实验，分析了普通物理实验教学在重建认知结构中的特殊作用。     

Nonlinear rheological behavior of silica filled solution‐polymerized styrene butadiene rubber

The reinforcement and nonlinear viscoelastic behavior have been investigated for silica (SiO₂) filled solution‐polymerized styrene butadiene rubber (SSBR). Experimental results reveal that the nonlinear viscoelastic behavior of the filled rubber is similar to that of unfilled SSBR, which is inconsistent with the general concept that this characteristic comes from the breakdown and reformation of the filler network. It is interesting that the curves of either dynamic storage modulus (G′) or loss tangent (tan δ) versus strain amplitude (γ) for the filled rubber can be superposed, respectively, on those for the unfilled one, suggesting that the primary mechanism for the Payne effect is mainly involved in the nature of the entanglement network in rubbery matrix. It is believed there exists a cooperation between the breakdown and reformation of the filler network and the molecular disentanglement, resulting in enhancing the Payne effect and improving the mechanical hysteresis at high strain amplitudes. Moreover, the vertical and the horizontal shift factors for constructing the master curves could be well understood on the basis of the reinforcement factor f(φ) and the strain amplification factor A(φ), respectively. The surface modification of SiO₂ causes a decrease in f(φ), which is ascribed to weakeness of the filler–filler interaction and improvement of the filler dispersion. However, the surface nature of SiO₂ hardly affects A(φ). © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2594‐2602, 2007     

含椭球包体多相复合介质电导率的有效介质理论

本文应用有效介质理论(EMT),研究含椭球包体的多相复合介质中的导电性。建议用各向异性因子m估计非均匀系统的局域各向异性,并给出一个计算此情况下有效电导率张量的公式。对于椭球包体取向完全无序的介质,建议以介质的几何结构因子I_i(i=χ,y,z)估计组成包体的颗粒之间的近场效应。研究表明,结构因子I_i与包体的退极化因子n_i(i=χ,y,z)之间存在简单的关系。EMT的计算结果表明,抻长的椭球包体(b/α≈0.2)和压扁的椭球包体((b/α≈7—8)是导致渗流阈值对c₁^*=0.17的两种主要几何结构。初步的理论分析表明,由这两种几何形状产生渗流的共同机制是在介质中形成“无穷”长的链状集团。     

Preparation of dye-loaded SiO2 nanoparticles

A room temperature method for the encapsulation of pyrene in SiO₂ nanoparticles is described. The relation between alkoxysilane surfactant chain length, reactant molar ratios and the uptake of dye, sample morphology, photophysical properties, and the ability of the silicate matrix to protect the encapsulated dye was examined. The synthesis can easily be adapted for the encapsulation of other hydrophobic and thermolabile substances, and used in the development of nanostructured optically active coatings, films and monoliths.     

Frame Wavelets with Compact Supports for L^2（R^n）

The construction of frame wavelets with compact supports is a meaningful problem in wavelet analysis. In particular, it is a hard work to construct the frame wavelets with explicit analytic forms. For a given n × n real expansive matrix A, the frame-sets with respect to A are a family of sets in R^n. Based on the frame-sets, a class of high-dimensional frame wavelets with analytic forms are constructed, which can be non-bandlimited, or even compactly supported. As an application, the construction is illustrated by several examples, in which some new frame wavelets with compact supports are constructed. Moreover, since the main result of this paper is about general dilation matrices, in the examples we present a family of frame wavelets associated with some non-integer dilation matrices that is meaningful in computational geometry.