含氮试剂对P-DCC／AICl3引发异丁烯正离子聚合的影响。

以对-二枯基氯（DCC），Alcl，体系引发异丁烯在二氯甲烷（CH2C12）正己烷（Hex）（40／60，V／V）混合溶剂中进行正离子聚合，探讨了DCC用量、含氮试剂2，6-二叔丁基吡啶（DtBP）和三苯胺（TPA）对异丁烯正离子聚合转化率、产物分子量及其分布的影响．结果表明，DCC和体系中微量水均可与A1C1，产生竞争络合，形成两种活性中心并引起相继的竞争引发，聚合产物的GPC谱图呈双峰分布，分子量分布宽；增加DCC用量有利于DCC与A1C1，的络合，致使链增长反应主要通过DCC与A1C1，络合形成的活性中心引发，但聚合产物分子量相对较低，分子量分布较宽；使用DtBP，可有效地抑制微量水引发及活性链向单体的转移反应，使分子量分布明显变窄，基本实现DCC的控制引发；采用DtBP与TPA共同调节聚合反应，可使聚合产物分子量分布变窄的同时，进一步提高分子量，从而得到相对较高分子量（Mw=103200）和单峰分子量分布（Mw／Mn=2．09）的聚异丁烯产物．     

Growth Mechanism of Vertically Aligned Ag（TCNQ） Nanowires

Highly oriented Ag(TCNQ) nanowires have been prepared on Si(111) wafer at 1O0℃ by the vapour-transport reaction between silver and TCNQ without any other catalyst. X-ray diffraction analysis shows that the composition and crystal structure of the obtained nanostructure were Ag(TCNQ) crystalline. Most Ag(TCNQ) nanowires were grown uniformly and vertically on the substrate with diameters ranging from 50 to 30Onto and the lengths measuring from 2 to 50μm by scanning electron microscopy. Ag particles were observed on the substrate from pure thin Ag film heated under the same conditions as used in synthesizing the nanowires. Nucleation and short Ag(TCNQ) nanowires were prepared by controlling the reaction time, providing direct evidence of the growth mechanism in a nanometre scale. The growth process was explained according to the vapour-liquid-solid model. The gradient of temperature and the densely distributed Ag particles may contribute to the vertically aligned growth. These results will be helpful for the controllable synthesis of Ag(TCNQ) nanowires.     

极性/非极性接枝共聚物PVIPA-g-PIB的合成研究

通过自由基共聚合方法,以AIBN为引发剂引发醋酸乙烯酯(VAc)和醋酸异丙烯酯(IPA)共聚,得到两者的无规共聚物聚(PVIPA).再以PVIPA作为大分子引发剂,以四氯化钛(TiCl4)为共引发剂,引发异丁烯进行正离子接枝共聚反应,分别考察了PVIPA/TiCl4/IB体系中TiCl4浓度、大分子引发剂浓度、陈化温度、陈化时间以及外加含氮亲核试剂2,6-二甲基吡啶(DMP)对异丁烯聚合转化率和PVIPA引发效率的影响,并采用GPC表征方法研究了聚合体系中两种引发活性中心(A)和(B)的引发竞争.实验结果表明,在没有外加亲核试剂的情况下,PVIPA与微量水均可参与与TiCl4的络合竞争,分别形成活性中心(A)和(B),并产生竞争引发异丁烯正离子聚合,生成相应的接枝共聚物PVIPA-g-PIB和均聚物PIB.TiCl4和PVIPA用量以及两者的络合作用温度与时间对异丁烯正离子接枝共聚起着重要作用.合适的TiCl4浓度与PVIPA浓度、低的微量水浓度以及在较低温度下使PVIPA与TiCl4充分络合,都有利于提高大分子引发剂PVIPA的引发效率.引发效率可以达到90%左右,并可制备出极性主链与非极性支链的接枝共聚物PVIPA-g-PIB,其GPC谱图呈现单峰分布,分子量分布(Mw/Mn)可达到2.17.此外,在聚合体系中加入适量含氮亲核试剂DMP,一定程度上可以提高PVIPA的引发效率.     

A method of finding the principal modes of nonlinear vibration systems and their stabilities

This paper presents a new method of finding the principal modes of nonlinear vibration systems, by means of which the problem of finding principal modes of nonlinear systems is transferred to the problem of finding real roots of a set of algebraic equations. The method is applicable to various kinds of nonlinear vibration systems with many degrees of freedom, and is simple in calculation. The paper presents another new method of analyzing the stabilities of principal modes of nonlinear systems.     

具有复杂边界条件的杆的振动分析

本文研究一端带有集中质量并支以弹簧另一端作支承运动的杆的纵向振动.由于这个问题的边界条件比较复杂,且要考虑阻尼,因此本文只求稳态周期解.首先分析线性系统;然后考虑材料非线性,用摄动法求具有非线性边界条件的非线性方程的近似解析解.     

一种提取物体相位变化率信息的理论和方法

利用部分相干光成像理论,推出傅科(Foucault)刀口相位检测时非相干光入射情况下的像面光强分布.分析表明,在一定条件下,可得到输入物函数相位变化率分布的信息.同时提出一种获取物相位变化率信息的装置,并分析了该装置的成像情况.     

Watson变换及其应用

该文讨论Watson变换和它在电磁波理论及工程中的应用。针对这一变换在高频电磁波问题中的应用,研究了复积分路径变换原则和选取方法,研究了曲面绕射理论中不同区域绕射函数宗量、波场振幅、绕射相位函数的一致性问题;得到了这类参量的一致性函数表达式。     

精密滴定量热计的改进及联机

LKB8700精密量热系统的滴定量热计是用于常量的量热测定,反应器是进口的玻璃容器。加热器、温度计、滴定管均装在反应器内,不便装样和清洗,滴定液进口只有一个,三种液体的混合只能分步滴定,热敏电阻随温度的变化用惠斯登电桥测量。针对快速反应手动跟踪较为困难这一情况,特别是为了研究油田应用的油-水-表面活性剂三元体系或多元体系,我们设计和建立了图1所示不锈钢制反应器,并在桥路输出中与微机相联接(图2),实     

丙烯酸甲酯-异丁烯交替共聚反应机理和动力学研究

本文研究了丙烯酸甲酯(MA)和异丁烯(IB)在AlEtCl_2,BPO存在下的聚合反应机理及动力学。结果表明:当[IB]≥[MA]时,共聚合是按三元络合单体(T)均聚的机理进行,形成(MA)-(IB)的交替共聚物;当[IB]<[MA]时,则形成富MA的含MA嵌段序列的共聚物,共聚是由三元络合单体(T)和二元络合单体(B),按无规共聚机理进行的。     

Controllable Passively Q-Switched Laser

We present a novel kind of pulsed laser named controllable passively Q-switched laser (CPQL). A CPQL of Nd:YV04 with Cr:YAG as saturable absorber was demonstrated and studied as an example of the kind of pulsed lasers. In CPQL, as the actively controlling signal, a diode laser beam was focused onto the saturable absorber in the resonant cavity of the passively Q-switched laser (PQL) and was absorbed by the absorber to realize the active control of the CPQL. The characters of the CPQL output laser pulses, such as generation time, repetition rate, pulse width, peak power and energy per pulse, can be controlled by the operator. The CPQLs possess theadv antages of both passively Q-switched laser and actively Q-switched laser. Because of their compactness, low cost and controllability, the CPQLs will find wide applications in many fields.