有机可溶性聚酯酰亚胺的合成及其液晶分子取向特性研究

采用偏苯三酸酐酰氯（TMAC）与乙二醇反应制备了含有酯键的乙二醇双苯甲酸酯-3,3’,4,4′-四酸二酐（TMEG）。然后采用该二酐单体分别与芳香族二胺单体,包括4,4′-二胺基二苯甲烷（MDA）、4,4′-二胺基二苯胺（NDA）、1,4-双[2-（4-胺基苯基）-2-丙基]苯（BisP）以及1,3-双[2-（4-胺基苯基）-2-丙基]苯（BisM）通过两步化学亚胺化工艺制备了可溶性聚酯酰亚胺（PEsI）树脂。凝胶渗透色谱（GPC）测试结果显示,该系列PEsI树脂的数均分子量（M_n）在6.21×10⁴～1.64×10⁵ g/mol,表明TMEG具有较高的反应活性。该系列PEsI树脂在极性非质子性溶剂,如N-甲基吡咯烷酮（NMP）、N,N-二甲基乙酰胺（DMAc）等中具有良好的溶解性,但在低极性溶剂,如乙二醇丁醚（BC）体系中则不溶解。采用PEsI/NMP/BC体系配制了PEsI液晶取向剂,并以此装配了液晶盒。测试结果显示,基于TMEG的PEsI取向膜具有良好的耐热稳定性,其5%失重温度超过了400℃,玻璃化转变温度（T<...     

含氮杂环结构溶致液晶聚芳酰胺的合成和性能

将二胺1,2-二氢-2-(4-氨基苯基)-4-[4-(4氨基苯氧基)-苯基]-二氮杂萘-1-酮和对苯二胺与对苯二甲酰氯进行低温溶液缩聚反应并改变两种二胺的比例,制备出一系列共聚酰胺树脂.结果表明,共聚酰胺树脂的特性粘度为1.76-3.29 dL/g;随着主链中二氮杂萘酮结构比例的增加,聚合物的溶解性逐渐得到改善;该类聚合物具有较高的玻璃化转化温度(312～351 ℃);在氮气气氛中10%热失重温度为513～534 ℃;聚合物呈现无定型的状态,并且可以在浓硫酸、N-甲基吡咯烷酮/氯化锂、N,N-二甲基乙酰胺/氯化锂中呈现溶致液晶织构.     

L-Cys/EGDE对脆弱丝织品的加固及机理分析

采用L-半胱氨酸(L-Cys)和交联剂乙二醇二缩水甘油基乙醚(EGDE)为加固材料对脆弱丝织品进行加固,通过正交实验得到较优加固方案:L-Cys质量浓度15 g/L,EGDE的质量浓度25 g/L。在此条件下加固的脆弱丝织品断裂强力由(2±0.3)N提高到(18±0.5)N,断裂伸长由(3±0.5)mm提高到(14±0.5)mm。傅里叶红外光谱仪(FT-IR)、13C固体核磁共振仪(13C CP/MAS NMR)和氨基酸测试结果表明,L-Cys/EGDE加固材料与脆弱丝织品中酪氨酸、组氨酸等氨基酸侧基发生了稳定的化学反应,加固样中无规卷曲结构大量增加,加固效果明显。该方法工艺简单,效果显著,适于脆弱丝织品文物的加固。     

丝素蛋白/乙二醇二缩水甘油醚对老化丝纤维的加固

在制备人工老化样的基础上,利用丝素蛋白/乙二醇二缩水甘油醚对老化丝纤维进行加固,并对加固前后的丝纤维进行了性能和结构表征。研究结果表明,丝素蛋白与乙二醇二缩水甘油醚发生了化学反应;反应位点为Tyr羟苯基上的羟基、Lys上的氨基、His咪唑基上的亚氨基等;加固样的断裂强力从1.54 N提高到15.8 N,伸长率从2%提高...     

RTM聚酰亚胺树脂性能优化设计研究

综合考虑耐热性、流变性能、开放期以及树脂固化后的玻璃化转变温度等因素,对PETI聚酰亚胺树脂进行优化.研究分子量对优化体系的影响.结果表明:以苯乙炔苯酐(4-PEPA)为封端基,选择非对称的二酐(a-BPDA),引入3,4'-二苯醚二胺(3,4'-ODA)和4,4'-二苯醚二胺(4,4'-ODA)等比例合成出低粘度的树脂,当分子量为750g/mol时,该PE-TI聚酰亚胺树脂能满足RTM工艺要求,能够实现高温复合材料的低成本制造.     

DHPZ-DA/DAPE/PPD/NDA杂萘聚芳酰胺的合成及性能

由自制二胺1,2-二氢-2-(4-氨基苯基)-4-[4-(4-氨基苯氧基)-苯基]-二氮杂萘-1-酮(DHPZ-DA)、4,4‘-二氨基二苯醚(DAPE)和对苯二胺(PPD)与2,6-萘二酸(NDA)进行共缩聚反应,改变不同二胺的配比,所得聚芳酰胺树脂特征粘度为0.24 dL/g～2.78 dL/g ;以FT-IR、1H-NMR手段分析了聚合物的结构;用DSC、TGA手段研究了聚合物的耐热性能.结果表明,该类聚合物具有较高的玻璃化转变温度(280 ℃以上);氮气气氛中5%热失重温度在450 ℃以上;当DHPZ-DA DAPE在二胺中比例达70%时能溶于NMP中,当DHPZ-DA DAPE含量达80%时能溶于DMAc、DMF等非质子极性溶剂中.     

氨羧钾调控草酸钙晶体生长及其与分子结构的关系

采用扫描电子显微镜(SEM)和X射线衍射(XRD)在凝胶体系中研究了不同结构氨羧钾对草酸钙(CaOxa)结晶的影响,这些氨羧钾包括氨基乙酸钾(KGLY)、乙二醇二乙醚二胺四乙酸二钾(K2EGTA)、氨基三乙酸二钾(K2NTA)、二乙三胺五乙酸二钾(K2DTPA)、乙二胺四乙酸二钾(K2EDTA)和环已二胺四乙酸二钾(K2CDTA).这些物质均能诱导二水草酸钙(COD)形成,抑制一水草酸钙(COM)聚集和减小COM的比表面积,其诱导COD能力依次为:K2DTPA(55wt%)K2EDTA≈K2CDTA(50wt%)K2NTA(43wt%)K2EGTA(4wt%)KGLY(2wt%),抑制COM聚集的能力依次为:K2DTPAK2NTAK2CDTA≈K2EDTAK2EGTAKGLY.从氨羧盐的分子结构、羧基的相对含量、羧基的空间位置、与钙离子的配位能力及其配位方式等角度讨论了其抑制COM聚集和诱导COD形成的化学基础.结果表明K2NTA和K2DTPA有可能成为防止草酸钙结石形成的潜在药物.     

防潮型高吸水树脂的制备及性能研究

采用溶液聚合法制备防潮型高吸水树脂,以丙烯酸(AA)、丙烯酰胺(AM)为单体,N,N′-亚甲基双丙烯酰胺(NMBA)为交联剂,过硫酸钾(KPS)和亚硫酸氢钠为引发剂,乙二醇二缩水甘油醚和1,4-丁二醇为二次交联剂制备吸水树脂。通过红外、热重和光学显微镜等技术对吸水树脂的结构和形貌进行表征,以及对吸水树脂的吸水性能和吸湿性能进行测试。结果表明:二次交联剂的加入可以在吸水树脂表面形成一层高度交联的表面层,且在乙二醇二缩水甘油醚和1,4-丁二醇复配比为1∶1时,吸湿倍率最低,较普通高吸水树脂吸湿率下降75%。     

二联噻吩和联苯胺类交替共聚物的合成及表征

以联苯二胺及二甲基联苯二胺为原料,合成了相应的N,N′-二氯联苯醌胺单体,并以二价镍配合物为催化剂与二连噻吩共聚得到了相应的交替共聚物。所得聚合物通过FT-IR,1H-NMR进行了表征。所得聚合物紫外-可见光谱分别在330、437、327、410nm处最大吸收峰出现。所得聚合物在-0.1～0.8V之间进行循环伏安分析,每一个聚合物都观察到两对氧化峰和还原峰分别在(Epa=0.40V/Epc=0.31V和Epa=0.70V/Epc=0.56V)和(Epa=0.33V/Epc=0.28V和Epa=0.63V/Epc=0.50V)。     

耐高温高韧性聚酰亚胺树脂分子量与性能关系

首先,采用具有非对称结构的2,3,3',4'-联苯四甲酸二酐（α-BPDA）、二胺以及反应性封端剂4-苯乙炔苯酐（4-PEPA）合成了分子量分别为1 500、2 500、3 500、5 000 g/mol的热固性聚酰亚胺树脂;然后,采用FTIR、XRD、DSC、DMA、TGA和流变等表征分析方法,研究了分子量与固化反应过程、聚集态结构、耐热性能、流变性能、韧性性能的关系及其影响机制。结果表明:随着分子量增加,热固性聚酰亚胺树脂的玻璃化转变温度由369 ℃下降至344 ℃;熔体最低黏度由15.5 Pa·s增加至37 090.0 Pa·s;冲击强度由25.93 kJ/m2提高到45.04 kJ/m2。增大分子量导致热固性聚酰亚胺树脂的玻璃化转变温度和工艺性能下降,但韧性提高。      

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.     

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.     

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.     

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)。