萘基侧链型阴离子交换膜的制备

采用ATRP反应合成了聚苯乙烯甲基苯乙烯的全碳主链聚合物,侧链接枝含萘基及长烷基链的季铵型阳离子功能化基团,制备了萘基侧链型阴离子交换膜.电镜观察到膜内存在明显的微相分离结构,小角X光散射也证明其存在较大的离子域,这可归因于膜主链与侧链亲疏水性的显著差异.其中,PSMS-NAPMQA-5膜在80℃离子电导率为98.53...     

哌啶阳离子功能化侧链型阴离子交换膜的制备

燃料电池因其能量转化率高、污染小等特点,成为当前的研究热点.然而,作为关键部件的阴离子交换膜仍然存在离子电导率低、耐碱性能差等缺点,这限制了燃料电池的发展.利用威廉姆森成醚反应在聚醚酮主链接枝哌啶鎓盐,成功制备了侧链型阴离子交换膜.设计的哌啶鎓盐通过长柔性亚甲基与主链相连,使膜内形成有利于高效离子传输的微相分离结构,PEKCQA-1.0膜在80℃的电导率高达72.7mS/cm.此外,哌啶阳离子基团离主链较远,减弱了对主链的吸电子作用;同时,环型结构的哌啶阳离子具有一定的空间位阻,减少了OH~-对阳离子基团的攻击,使膜表现出优异的耐碱性能.PEK-CQA-0.8膜在60℃下1mol/L KOH水溶液中浸泡360h后,离子电导率仅下降了8.8%,有望应用于碱性燃料电池.     

全氟阳离子聚合物的合成及膜结构与性能研究

高碱稳定性、高离子电导率的阴离子交换膜的设计与制备是近年来燃料电池领域研究的前沿和热点.从分子设计出发,以在聚合物主链上引入稳定性优异的氟原子为基础,在侧基上进行功能性基团的嫁接,合成了吗啉、直链季铵、咪唑型的全氟阳离子聚合物,并将这些聚合物制成相应的阴离子交换膜.结果显示,所得3种阴离子交换膜在80℃水中的离子电导率为60.4～80.6mS/cm.其中,直链季铵型阴离子交换膜在80℃下的电导率达到80.6mS/cm.此外,在80℃,8 mol/L KOH水溶液中浸泡10d后,离子膜的IEC和电导率分别保留了92.7%和93.2%,表现出优异的耐碱性能.     

季铵化聚醚醚酮阴离子交换膜的制备及性能研究

以四甲基联苯二酚和二氟二苯甲酮为单体通过缩聚反应、溴化、季铵化、碱化制备了不同季铵化的聚醚醚酮阴离子交换膜。利用核磁共振氢谱(1 H-NMR)、红外光谱(FT-IR)对聚醚醚酮的结构进行了表征,并测试了膜的各项性能。结果表明,溴代率为65%的QPAE-b膜性能最好,离子交换容量(IEC)为1.24mmol/g,80℃吸水率(WU)为120%、溶胀率(SR)为34%、电导率为27.9ms/cm,说明QPAE-b膜在碱性阴离子交换膜燃料电池方面有很好的应用前景。     

侧链磺化聚醚醚酮质子交换膜的制备及性能

为进一步提高磺化聚醚醚酮质子交换膜的尺寸稳定性、耐氧化性和质子电导率,从侧链结构出发设计制备了一种新的侧链型磺化聚醚醚酮质子交换膜.以磺化聚醚醚酮为聚合物主链,利用N,N′-羰基二咪唑(CDI)的活化作用将1-乙醇胺(MEA)与磺酸基团反应,从而延长侧链长度,再通过1,3-丙磺酸内酯的开环反应引入磺酸功能基团,最后采用溶胶-凝胶法制备出一系列新的侧链型磺化聚醚醚酮质子交换膜.对所制备的侧链型磺化聚醚醚酮质子交换膜分别进行了结构和性能表征.结果表明,该类侧链型磺化聚醚醚酮质子交换膜中产生了亲水/疏水相分离结构,并且具有适当的吸水率和较低的溶胀度(9.2%).该类质子交换膜具有更高的质子电导率,其中60℃时支化程度为80%的侧链型磺化聚醚醚酮质子交换膜的电导率高达0.096 S/cm.此外,制备的侧链型磺化聚醚醚酮质子交换膜也具有良好的机械性能、氧化稳定性和热稳定性.     

燃料电池用密集柔性侧链型阴离子交换膜的制备

以含氟聚芳醚为聚合物主链,通过接枝具有三功能位点的2,4,6-三(二甲氨基甲基)苯酚(TDAP)和1-溴己铵离子液体(Br-6-QA),成功制备了一系列新型的具有密集柔性侧链的聚芳醚类阴离子交换膜DFHF-TQA-x.疏水含氟主链和密集柔性侧链功能基团的引入有效促进了膜内亲水离子区域的聚集,DFHF-TQA-x膜显示出良好的微相分离结构,且在较低离子交换容量和含水率的情况下能获得较高电导率.DFHF-TQA-0.75膜在80℃下达最高电导率76.1 mS/cm,在60℃单电池测试电流密度为150 mA/cm~2时达最大功率密度80.7mW/cm~2,可适用于燃料电池.     

基于聚乙烯醇/支化聚乙烯亚胺离子交换膜不同烃基对其性能的影响EI北大核心CSCD

以聚乙烯醇/支化聚乙烯亚胺(PVA/BPEI)为基体,分别选用多种卤代烃为季铵化试剂制备阴离子交换膜(AEMs),并采用多种测试方法对膜的关键性能进行表征,以及基于分子结构对结果进行分析讨论。结果表明,以3-氯-1-丙醇为季铵化试剂制备所得的AEM于80℃电导率可达79. 03 m S/cm,IEC值为3. 1 meq/g,且该膜由于羟基在膜内形成的氢键作用使其具有优异的热力学性能、尺寸稳定性和化学稳定性;膜内季铵基团随其疏水链长度及结构的不同对AEMs性能的影响也有所差异,引入含有羟基的柔性侧链可在膜内构成氢键网络形成亲疏水结构,是提高膜综合性能的有效途径。     

基于聚乙烯醇/支化聚乙烯亚胺离子交换膜不同烃基对其性能的影响

以聚乙烯醇/支化聚乙烯亚胺(PVA/BPEI)为基体,分别选用多种卤代烃为季铵化试剂制备阴离子交换膜(AEMs),并采用多种测试方法对膜的关键性能进行表征,以及基于分子结构对结果进行分析讨论。结果表明,以3-氯-1-丙醇为季铵化试剂制备所得的AEM于80℃电导率可达79. 03 m S/cm,IEC值为3. 1 meq/g,且该膜由于羟基在膜内形成的氢键作用使其具有优异的热力学性能、尺寸稳定性和化学稳定性;膜内季铵基团随其疏水链长度及结构的不同对AEMs性能的影响也有所差异,引入含有羟基的柔性侧链可在膜内构成氢键网络形成亲疏水结构,是提高膜综合性能的有效途径。     

咪唑季铵化聚合物碱性阴离子交换膜的研制及表征

以十二烷基磺酸钠和辛基酚聚氧乙烯醚为复合乳化剂、水溶性的过硫酸铵为引发剂,通过乳液聚合的方法合成了对氯甲基苯乙烯、丙烯酸丁酯和苯乙烯的三元共聚物,并对其进行季铵化和碱性化改性制备了新型的碱性阴离子交换膜.通过傅里叶变换红外光谱法对其进行化学结构表征,采用热重分析法表征其热稳定性,测定了碱性膜的电导率、离子交换膜容量、吸水率、化学稳定性等理化性能.结果表明:制备的碱性膜,在室温下的电导率为3.824mS/cm,离子交换容量为0.514 4mmol/g,吸水率为22.79%,6mol/L KOH溶液中的降解时间大于20天,具有较高的热稳定性和耐溶剂性.     

含柔性侧链季鏻阳离子结构的聚芳醚腈阴离子交换膜（英文）

为有效改善聚合物阴离子交换膜材料(AEMs)的性能,本研究在综合考虑聚合物结构、离子官能团种类及其链接方式对AEMs影响的基础上,设计制备了一系列含有柔性侧链型季鏻阳离子结构的新型聚芳醚腈(PAEN-TPP-x)阴离子交换膜.分别对所制聚芳醚腈阴离子交换膜的合成方法、结构和离子交换容量、吸水率、溶胀率、氢氧化物电导率及碱稳定性进行了系统研究,并与一些其他已报道的AEMs进行了比较研究,以进一步探索其结构与性能之间的关系.研究发现所制备的含有柔性侧链型季鏻阳离子结构的聚芳醚腈阴离子交换膜具有良好的综合性能.在60℃下,它们的吸水率、溶胀率和离子传导率分别为11.6%–22.7%,4.4%–7.8%和28.6–45.8 mS cm^-1.与此同时,该类AEMs还表现出良好的碱性稳定性,其中代表性样品PAEN-TPP-0.35在2 mol L^-1NaOH溶液中、60和90℃下浸泡480 h后的OH-传导率分别保持在其初始值的82.1%和80.6%.本研究可为高性能聚合物阴离子交换膜材料的设计制备和改性提供新的思路和方法.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。