陀螺仪壳体翻滚系统

为提高陀螺仪的精度，采用壳体翻滚自动补偿与壳体有关的漂移误差力矩。介绍了一种无刷直流伺服电动机数字控制系统，并与俄罗斯－Ⅱ－15仪表的模拟控制系统做了比较。同时在运动件和固定件之间设计了一套特殊的导电装置。实验表明该导电装置使用寿命长、可靠性高。     

传热结构的多目标拓扑优化设计研究

深入分析了传热结构多目标拓扑优化设计中的几个关键问题。提出了基于结构柔度最小化和结构散热弱度最小化的多目标拓扑优化设计方法,建立了传热结构的多目标拓扑优化设计模型,推导了传热结构多目标拓扑优化中用于迭代分析求解的优化准则算法和敏度分析方程。通过数值计算验证了理论和算法的有效性。     

Effect of Radiation Scattering on the Dynamics of the Transitional Zone During Solidification of a Semitransparent Material

The effect of isotropic scattering in a two-phase zone on the velocity of boundaries, thickness of the transitional zone, and distribution of the solid phase over the two-phase zone thickness in the course of solidification of a semitransparent material is considered. A generalized model of phase transition in a semitransparent medium is used. The results of numerical calculations show that radiation scattering can exert a significant effect on the structure and size of the two-phase zone and also on heat transfer (temperature gradient) in the crystal being formed.     

碳系导电油墨印刷RFID天线性能增强工艺研究

随着互联网和RFID技术的快速发展,RFID天线的导电性能非常关键。采用炭黑和石墨混合物和树脂制备9种碳系导电油墨,基于四种不同镀铝膜丝网印刷RFID标签天线再NaOH溶液腐蚀后测量油墨的附着力、导电墨层的厚度、天线的电阻率,分析影响RFID天线导电性能的因素。     

Mechanisms for Imparting Conductivity to Nonconductive Polymeric Biomaterials

Traditionally, conductive materials for electrodes are based on high modulus metals or alloys. Development of bioelectrodes that mimic the mechanical properties of the soft, low modulus tissues in which they are implanted is a rapidly expanding field of research. Many polymers exist that more closely match tissue mechanics than metals; however, the majority do not conduct charge. Integrating conductive properties via incorporation of metals and other conductors into nonconductive polymers is a successful approach to producing polymers that can be used in electrical interfacing devices. When combining conductive materials with nonconductive polymer matrices, there is often a tradeoff between the electrical and mechanical properties. This review analyzes the advantages and disadvantages of approaches involving coating or layer formation, composite formation via dispersion of conductive inclusions through polymer matrices, and in situ growth of a conductive network within polymers.

     

PEDOT∶PSVMA/AuNPs导电墨水的合成及应用

本文以苯乙烯磺酸钠(SS)、7-(4-乙烯基苄氧基)-4-甲基香豆素(VM)和丙烯酸(AA)作为反应单体,合成了一种光敏性双亲共聚物PSVMA,利用1 HNMR与UV-Vis光谱对其结构和组成进行了表征。以PSVMA作为软模板和掺杂剂,氯金酸作为氧化剂,通过化学氧化法聚合得到水分散的PEDOT∶PSVMA/AuNPs导电复合物,平均粒径是66.7±0.5nm。将其作为基础墨水,调节配方制得了PEDOT∶PSVMA/AuNPs喷墨打印墨水,分别以相纸和PET膜为基材制得了图案化的柔性导电膜,该柔性导电膜具有较好的导电性,经紫外光引发导电膜中的香豆素基团二聚后,其耐水性大大提高。     

Molecular Weight Development of Surface and Solution Polymers in Surface‐Initiated Atom Transfer Radical Polymerization and Their Dependence on Radical Termination Modes

In the surface‐initiated atom transfer radical polymerization, the polymerization proceeds both in solution and on surface. This work reports a modeling study, describing the growth of the molecular weight and polydispersity of polymer both on surface and in solution. It is found that both surface radical termination and solution monomer consumption significantly suppress the growth rate of polymer layer. Besides, the former affects the molecular weights of polymer both on surface and in solution. If the termination rate constant in solution (k_t,sol–sol) is the same as that of surface and solution interfaces (k_t,sol–surf), and the surface termination (k_{t,surf–surf}) is negligible, then the polymers both on surface and in solution have the same molecular weight. However, if surface radicals terminate among themselves, the molecular weight of polymer on surface will lower than that in solution. Such termination is promoted by surface radical migration through activation/deactivation reactions in solution. When k_t,sol–surf <k_t,sol–sol, the molecular weight of surface polymer becomes higher than that in solution. This situation is resulted from surface radical trap due to a high grafting density.

     

Two‐Dimensional Au Nanocrystals: Shape/Size Controlling Synthesis,Morphologies, and Applications

The fascinating roles of two‐dimensional (2D) nanomaterials in natural super‐strong bio‐composites (i.e. aragonite platelets in nacre and apatite platelets in bone) have aroused great interest in scientific communities to synthesize their artificial counterparts with controllable geometric and physical properties. The quantum 2D confinement of electrons recently revealed in graphene nanosheets further inspires to explore 2D metal nanocrystals with intrinsic anisotropic properties and quantum size effect. Among them, 2D Au nanocrystals stand out not only due to their unique structure‐ and environmental‐dependent properties, but also due to their rapid development in synthesis approaches and emerging applications in electronics, optics, sensing and biomedicines. In this Review the aim is to rationalize numerous newly published studies on 2D Au nanocrystals and to gain insight into their shape/size controlling synthesis, diverse morphologies, properties, and applications, potentially serving a handy guide to achieve on‐demand 2D Au nanocrystals.     

Annealing induced electrical conductivity jump of multi‐walled carbon nanotube/polypropylene composites and influence of molecular weight of polypropylene

Multi‐walled carbon nanotube (MWCNT)/polypropylene (PP) composites were prepared by a micro melt mixing process. As‐prepared composites had relatively low electrical conductivity due to the disruption of MWCNT network by strong shear. The electrical conductivity jumped to high values throughout an annealing process above the melting temperature of PP. The significant enhancement of electrical conductivity was influenced by annealing time, temperature, and content of MWCNTs. In particular, molecular weight of PP played an important role in affecting the conductivity enhancement. The molecular weight of PP was varied from 190,000 to 340,000 to examine its effect on the electrical conductivity. By comparing the conductivity enhancement behavior of composites with different molecular weight PPs and observing the morphology evolution during annealing, it was found that reaggregation of MWCNTs and the subsequent formation of MWCNT network during annealing are the main reasons for the jump of electrical conductivity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010