Electropolymeric generation of optically active polypyrrole

The facile synthesis of optically active polypyrrole has been achieved via the enantioselective electropolymerization of pyrrole on indium-tin-oxide-coated glass electrodes in aqueous solution containing D-(+) or L-(-) tartaric acid, (1S)-(+)-10-camphorsulfonic acid and L-lactic acid. The dark films of conducting polypyrroles salt formed under electrostatic conditions (+0.65V vs. Ag/AgCl) exhibited strong circular dichroism (CD) spectra typical of polymers possessing helical chirality. The quantitative reversal of the CD spectrum of the salt grown in (+)-tartaric acid as opposed to (-)-tartaric acid suggests that electropolymerization is highly enantioselective, with one helical screw of the polymer chain being preferentially produced depending on the hand of the tartaric anion incorporated. (C) 1997 Elsevier Science Ltd.

Morphological, thermal, and mechanical properties of polypropylene/polycarbonate blend

This work deals with the effect of compatibilizer on the morphological, thermal, rheological, and mechanical properties of polypropylene/polycarbonate (PP/ PC) blends. The blends, containing between 0 to 30 vol % of polycarbonate and a compatibilizer, were prepared by means of a twin-screw extruder. The compatibilizer was produced by grafting glycidyl methacrylate (GMA) onto polypropylene in the molten state. Blend morphologies were controlled by adding PP-g-GMA as compatibilizer during melt processing, thus changing dispersion and interfacial adhesion of the polycarbonate phase. With PP-g-GMA, volume fractions increased from 2.5 to 20, and much finer dispersions of discrete polycarbonate phase with average domain sizes decreased from 35 to 3 mu m were obtained. The WAXD spectra showed that the crystal structure of neat PP was different from that in blends. The DSC results suggested that the degree of crystallization of PP in blends decreased as PC content and compatibilizer increased. The mechanical properties significantly changed after addition of PP-g-GMA. (C) 1997 John Wiley & Sons, Inc.

Isothermal crystallization studies on neodymium oxide filled nylon 6

Melt mixing of nylon 8 with neodymium oxide particles was carried out with a single-screw extruder. The crystal behaviors of plain nylon 6 and the neodymium oxide filled nylon 6 mixture were studied by means of isothermal crystallization kinetic analysis. Isothermal crystallization thermograms obtained by differential scanning calorimetry (DSC) were analyzed based on the Avrami equation. The neodymium oxide particles acted as a nucleating agent in the mixture. The overall rate of di-isothermal crystallization of the neodymium oxide filled nylon 6 mixture is higher than that of plain nylon 6. The mechanism and modes of plain nylon 6 were the same as those of neodymium oxide filled PA6 mixture.

FRACTURE-TOUGHNESS AND MORPHOLOGY OF PHENOLPHTHALEIN POLY(ETHER SULFONE) THERMOTROPIC LIQUID-CRYSTALLINE POLYMER BLENDS

Blends of a new phenolphthalein poly (ether sulfone) (PES-C) and a thermotropic liquid crystalline polymer (LCP) were prepared by melt-blending in a twin-screw extruder. Rheological properties, fracture toughness, K(IC), and morphology of the blends were

EFFECT OF ANTIOXIDANTS ON PROPERTIES AND MORPHOLOGY OF POLY(ACRYLONITRILE BUTADIENE STYRENE) POLYCARBONATE BLENDS

Poly(acrylonitrile-butadiene-styrene), polycarbonate (PC), and two types of antioxidants have been blended by an extruder twin screw. Notched Izod impact strength, tensile property, and melting flow index (MFI) were measured for the blends including diffe

ON THE PHASE-STRUCTURE OF BLENDS OF POLYCARBONATE WITH POLY(ACRYLONITRILE-BUTADIENE-STYRENE)

Polycarbonate (PC) and poly(acrylonitrile-butadiene-styrene) (ABS) was co-extruded at different weight ratios by a single screw extruder. In order to obtain a finer blend, two times extrusion was carried out. In this case, a ''network'' structure with two-continuous phases was observed for the blends with two compositions of PC/ABS, being 80/20 and 70/30. It is found that the blends with these two compositions just have maximum values on the curves of notched Izod impact strength, flexural modulus and flexural strength vs. composition, respectively. This was never observed in previous publications.

HELIX-INDUCED ASYMMETRIC POLYMERIZATION

Asymmetric polymerization could be induced by an already formed optically active living prepolymer with one-handed screw sense helix conformation. The usually formed anionic active centre on the prepolymer could be changed to cationic, radical and even of Ziegler-Natta type. These living prepolymers with various kinds of active centre were all effective to induce a consequent asymmetric polymerization of a monomer which may be other than that in the prepolymer, to afford an optically active helical chain with the same screw sense as that of the prepolymer. Eight monomers have been used in the work. Optical rotation, circular dichroism and gelpermeation chromatography have been taken to prove the helix-induced asymmetric polymerization.

对螺钉无轴向压力的高精度自动螺丝刀的设计

区别于现有的电动、气动螺丝刀工具,该螺丝刀系统在驱动螺丝时,能对螺钉头实现无轴向压力的调节。刀头在旋转的同时随螺钉轴向进给,转速与进给量匹配,保证刀头与螺钉不脱节。该系统调整精度高,刀头转动精度可达0.72°,其应用于断路器类低压电气产品的自动调试,对确保产品质量、提高生产效率具有积极意义。

具有自适应能力管道机器人的设计与运动分析

提出并研制一种基于自适应移动机构的管内探查机器人。通过对机器人传动机构的设计,实现了在不增加驱动电动机数量的前提下,机器人具有适应不同管道直径的能力。机器人的传动机构能够在管道直径改变时,自动地改变行走部件的输出形式以克服障碍,完成越障任务。在没有应用链式多节构型的情况下,机器人配备一个驱动电动机就能够完成越障任务,改善了传统螺旋驱动式机器人越障能力不高的问题,同时也提高了对驱动电动机的使用效率。为了分析试验中发现的机器人保持架自转现象,对机器人进行运动分析,并由分析结果对相关部分进行改进。试验结果表明,该机器人能够在内径为190 mm和180 mm的管道中行进,并能够顺利通过两节管道间形成的同心台阶障碍,验证了自适应移动机构的行走能力。

一种适用于多指灵巧手的机电一体化驱动器概念

本文提出了一种机电一体化驱动器的概念,这种驱动器能够将电机的旋转运动转换为直线运动,并在不外加力和力矩传感器的基础上利用运动转换副上产生的微应变来估算电机的输出力矩和驱动器末端的牵引力信息。利用高精度、高灵敏度并带有温度和噪声补偿电路的应变片来测量微应变,以取得稳定而可靠的测量结果。应变片直接贴在驱动器的主体结构表面可以最小化尺寸,而且可以实现机电一体化而不是机械-电子集成系统。仿真实验表明,这种方法和传统的电流估算法相比,可以减少由于噪音和波动带来的电流信号误差,得到更加精确的信息,并且(与加入力或者力矩传感器相比)能够有效缩小外型尺寸,同时去除不必要的机械与电子接口,因此增加了系统的鲁棒性。

大型铰接并联六维测力平台摩擦建模

在已有制造工艺及标定技术基础上,为进一步改善大型铰接并联六维测力平台的测量精度,本文基于螺旋理论和影响系数原理,引入符号函数建立了Stewart结构大型铰接六维测力平台的摩擦模型。文中提出了关节摩擦对铰接并联六维测力平台测量精度的影响矩阵及I、H类误差表达式,绘制了在不同外载和关节摩擦系数条件下,六维测力平台的I、II类误差曲线,并总结丁关节摩擦和平台自重对测力平台测量精度的影响规律。为具有普通球形铰链人型Stewart平台六维测力下台精度的提高和改善提供了理论基础。

并联结构六维力传感器性能分析与优化设计

基于螺旋理论和空间模型理论绘制了Stewart平台型六维力传感器的性能图谱,总结了结构参数对传感器各性能指标的影响规律;在此基础上对大型Stewart平台六维力传感器的结构进行了非线性单目标、多目标优化设计,为具有普通球形铰链大型Stewart平台六维力传感器的设计和优化提供了依据。

基于立体视觉的移动机器人自主导航定位系统

描述了一种基于立体视觉的移动机器人自主导航定位系统。该系统采用双目立体视觉完成环境特征的 3D信息提取 ,实时计算出机器人相对作业目标的位姿 (6D)关系 ,导引移动机器人控制系统按目标导向进行运动。系统在相对位姿计算中采用旋动(Screw)理论 ,将带约束的多变量函数的非线性优化问题转化为线性方程组的最小二乘问题 ,简化了计算复杂性。实验表明 ,这个导航定位系统在定位精度和数据处理速度上均可满足机器人导航的要求。

LW-1型机器人重复位姿精度检测系统

本文介绍了一种非接触式（ＬＷ－１型）机器人重复位姿精度检测系统．该系统采用电涡流传感器作为位置信息传感器．以这种传感器的检测性能为基础，研究设计了相应的传感器测量结构、数学模型和坐标变换求解方法，使系统技术指标及使用性能达到了检测机器人重复位姿精度的实用要求．该系统具有鲁棒性强、设计合理、结构简单、造价低廉等特点，可以满足我国现阶段在机器人学研究和机器人开发应用方面的需求

遥控作业移动机器人环境建模方法研究

本文介绍了用于遥控机器人作业虚拟环境生成的建模方法．重点研究了基于人机交互的双目立体视觉和多视点建模方法，以克服视觉自动建模方法计算复杂、鲁棒性差的缺点．给出了环境建模的实验系统和实验结果。