Na^＋和Ti^4＋对CaO—Al2O3—SiO2系玻璃结构和晶化的影响

使用ＲＡＭＡＮ光谱和ＤＴＡ方法研究了含少量Ｎａ＋和Ｔｉ４＋的ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２系玻璃，发现在纯ＣＡＳ系玻璃（Ｃａ／Ａｌ≥１／２，Ａｌ／Ｓｉ≤１）中，Ａｌ３＋仅有一部分进入玻璃网络，少量Ｎａ＋的引入，有助于Ａｌ３＋进一步进入玻璃网络中，Ｎａ＋起了间接补强玻璃网络的作用，Ｎａ＋和Ｃａ２＋离子对Ａｌ３＋进入玻璃网络结构程度的影响可认为是Ｎａ＋和Ｃａ２＋离子分别以［ＡｌＯ４］Ｎａ和［ＡｌＯ４］Ｃａ［ＡｌＯ４］基团的形式进入玻璃网络中，由于结合几率和体积效应，使［ＡｌＯ４］Ｎａ较［ＡｌＯ４］Ｃａ［ＡｌＯ４］更易进入玻璃网络中。Ｔｉ４＋以［ＴｉＯ４］的形式进入玻璃网络，它对Ａｌ３＋是否能进入玻璃网络无明显影响。Ｎａ＋和Ｔｉ４＋的单独引入，均能使玻璃网络的聚合程度增强，析晶活化能提高；而当Ｎａ＋和Ｔｉ４＋同时引入时，玻璃网络聚合程度和纯ＣＡＳ系玻璃相差不大，析晶活化能有所降低。少量Ｎａ＋的引入，不会影响析出主晶相的种类和数量，而Ｔｉ４＋的引入，则会影响到所析出主晶相的种类和数量。     

SiC晶须增强陶瓷基复合材料的研究

用不同的Al_2O_3粉料,采用SiC晶须补强以及加入第三相SiC粒子弥散增韧的方式,研究了SiC晶须Al_2O_3基复合材料的力学性能,得到强度σ_f=780MPa,K_(Ic)=7.6MPa·m~(1/2)的结果。通过不同的分敌途径,对晶须分散效果进行了实验观察和探讨;并讨论了晶须的分散均匀性对力学性能的影响。同时,就晶须团聚体在增韧过程中所起的作用提出了一种新的、可能的增韧机制,合理地解释了实验结果。最后,就三元复合系统中晶须补强和弥散增韧两种途径的迭加效果进行了讨论。     

Living carbocationic polymerization

Summary Living carbocationic polymerization of styrene (St) has been achieved by the use of the 1(p-methylphenyl)ethyl acetate (pMePhEtOAc)·BCl₃ complex in CH₃Cl solvent at –30°C using both the IMA and AMI techniques. The living nature of the polymerizations has been demonstrated by linear M_n versus W_PSt (weight of polystyrene) plots passing through the origin and horizontal N (moles of PSt) versus W_PSt plots starting at N=I_o (the number of moles of initiator used). The molecular weight distribution MWD of the PSts is broad (M_w/M_n=~5–6) due to slow initiation and/or slow exchange between dormant and active species relative to propagation. The structure of the ester initiator strongly affects the rate and outcome of living polymerization, e.g., cumyl acetate (CumOAc), cumyl propionate (CumOPr), and 2,4,6-trimethylphenylethyl acetate (TMePhEtOAc), do not lead to truly living St polymerizations. The findings with the latter esters is explained in terms of a two path process comprising a slow living polymerization and a faster conventional cationic chain reaction. With phenylethyl acetate (PhEtOAc) living polymerization is achieved, however, initiation (cation generation) is slow. Forced termination by pyridine or methanol, or heating to ambient temperature leads to-CH₂CH(C₆H₅)Cl end groups.     

聚合转化率对硫调型氯丁胶结构与性能的影响

研究了硫调型氯丁橡胶乳液聚合中转化率对产晶结构与性能的影响.结果表明,随单体转化率的提高,聚合物的凝胶量及其交联密度增大,致使断链速度减慢,所得断链胶的门尼粘度上升,残存凝胶量增加,分子支化程度增大,分子量分布变宽,焦烧时间缩短。而相应硫化胶的拉伸强度、撕裂强度、冲击弹性和硬度等提高,扯断伸长率和永久变形下降。这些变化一般在转化率为80——85％时有明显转折.综合考虑产量与质量,聚合转化率控制在82±2％较为适宜。     

Effects of ultrasonic oscillation on processing behaviors of PS,EPDM, and PS/EPDM blend

In this study, the extrusion processing behaviors of polystyrene (PS), ethylene–propylene–diene terpolymer (EPDM), and their blend (PS/EPDM, 80/20) were studied by using a special ultrasonic oscillation extrusion system developed in our laboratory. The die pressure and volume flow rate were measured at different ultrasonic intensities and screw rotation speeds. The dependences on ultrasonic intensity of die pressure, volume flow rate, and apparent viscosity of polymers, as well as die swell at the same screw rotation speed were investigated. The effects of screw rotation speed on the processing behaviors of polymers and their blend at the same ultrasonic intensity were also studied. The experimental results showed that in the presence of ultrasonic irradiation, the processibilities of polymers and their blend were improved. Their possible mechanism is discussed in this article. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1856–1863, 2006     

Morphology and characterization of conductive films based on polyaniline‐coated polystyrene latexes

The polyaniline (PANI)‐coated polystyrene (PS) latexes were synthesized, and the electrically conductive films were prepared thereafter. The weight ratio of PANI was 5%. Thermal analysis of the latices was performed using DSC and TGA. In this study, the electrically conductive films were prepared above the PS glass transition temperature (T_g). During the film formation, the effects of the annealing temperature and atmosphere (air or N₂) on the film resistance were investigated. In addition, the film morphology was observed utilizing scanning electron microscopy. The film resistance decreased in the initial heating stage due to the increasing temperature and the compaction of film. Then the film resistance increased with further annealing due to the aging of PANI. Typically, the film resistance was about 6000 Ω/sq, and the conductivity was 0.3 S/cm. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5406–5413, 2006     

Spherical NiO-C composite for anode material of lithium ion batteries

Spherical NiO-C composite was prepared by dispersing spherical NiO in glucose solution and subsequent carbonization under hydrothermal conditions at 180 °C. The microstructure and morphology of the NiO-C and NiO powders were characterized by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical properties of the electrodes were measured by galvanostatic charge-discharge tests, cyclic voltammetric analysis (CV), and electrochemical impedance spectroscopy (EIS). SEM images showed that the amorphous carbon not only coated on the surface but also filled the inner pores of the NiO spheres. Electrochemical tests showed that the NiO-C composite exhibited higher initial coulombic efficiency (66.6%) than NiO (56.4%), and better cycling performances. The improvement of these properties is attributed to the carbon, as it can reduce the specific surface area of porous sphere, and enhance the conductivity of porous NiO.     

三羟甲基丙烷三丙烯酸酯的制备

介绍了一种制备三羟甲基丙烷三丙烯酸酯（ＴＭＰＴＡ）的方法──酰氯法。用本法可得纯度＞９９．９％、收率＞９８％的题示产物。原理简单，途径简捷，无需阻聚剂，大大简化了后处理工艺，成本降低。     

计算机远程控制的有关应用分析

通过远程控制软件介绍计算机远程控制的关键技术。在计算机普及速度加快的今天,计算机远程技术得到迅猛发展,研究计算机远程控制的应用,推动其推广和应用。本文论述计算机远程控制的应用,旨在为同行提供一些参考。