PVDF/SiO_2原位复合纳米纤维膜的制备及性能研究

采用原位复合溶胶一凝胶法配制复合纺丝液,通过高压静电纺丝制备出PVDF／SiO2复合纳米纤维膜。采用FTIR分析了PVDF与Si02分子间的相互作用,并通过TEM表征了纳米二氧化硅的具体分散状态。研究了纳米si02的加入对膜的热性能、结晶行为及力学性能的影响。结果表明,原位复合溶胶一凝胶法使纳米Si02在PVDF中具有...     

PVDF/SiO_2原位复合纳米纤维膜的制备及性能研究

采用原位复合溶胶-凝胶法配制复合纺丝液,通过高压静电纺丝制备出PVDF/SiO_2复合纳米纤维膜。采用FTIR分析了PVDF与SiO_2分子间的相互作用,并通过TEM表征了纳米二氧化硅的具体分散状态。研究了纳米SiO_2的加入对膜的热性能、结晶行为及力学性能的影响。结果表明,原位复合溶胶-凝胶法使纳米SiO_2在PVDF中具有良好的分散性,由FTIR可知在纳米SiO_2与PVDF分子间形成了C-O-Si键,使纳米粒子与PVDF基体形成了一定的结合力,进而提高了纤维的强度,且对纤维的热性能及结晶行为也产生了一定的影响。     

静电纺PVDF/SiO_2原位复合隔膜的研究

采用原位复合溶胶-凝胶法配制复合纺丝液,通过高压静电纺丝制备出PVDF/SiO2复合纳米纤维膜。通过SEM表征了PVDF/SiO2复合纳米纤维的纺丝效果,同时对比了使用两种方法添加6%SiO2制得的PVDF静电纺复合纳米纤维的表面形貌及力学性能。研究了原位纳米SiO2的加入对膜的孔径变化以及力学性能的影响。结果表明,原位硅的加入,增加了纤维的表面粗糙度;降低了复合膜内的微孔直径,并使得微孔直径分布更加集中;改善了膜的力学性能,添加6%原位硅时效果最佳。在SiO2含量为6%时,与直接添加相比,原位复合法制得的复合膜力学性能更佳。     

TiO2/聚乳酸复合纳米纤维膜的制备及其抗菌性能

采用静电纺丝技术,分别制备了纯聚乳酸(PLA)纳米纤维膜和不同TiO2含量的TiO2/PLA复合纳米纤维膜。利用扫描电子显微镜、傅里叶红外光谱和电子万能试验机分别对复合纳米纤维膜进行了形貌表征、成分分析和力学性能测试,用改良的振荡烧瓶法测试了复合纳米膜的抗菌性能。结果表明:随TiO2含量的增加,纤维直径减小而CV值和表面颗粒尺寸有所增加;复合纳米纤维膜中含有TiO2成分,证明TiO2与聚乳酸能够物理复合;添加适量的TiO2能够提高纳米纤维膜的断裂强度;在光催化条件下,TiO2/PLA复合纳米纤维膜对大肠杆菌和金黄色葡萄球菌表现出良好的抗菌性能,当TiO2含量为1%时,对两种菌的抑菌率分别达到92.9%和92.2%。     

亲水性PVDF/TiO2复合薄膜的制备及光催化性能

本实验采用平板刮膜法制备PVDF/TiO2复合薄膜,再通过超声清洗致孔剂并改变其亲水性,然后对样品薄膜的微观形貌、力学性能、光催化性能等进行研究与分析.研究发现:PVDF/TiO2复合薄膜的拉伸强度和光催化降解能力均随着TiO2的加入呈现先增后减的趋势,在TiO2添加量为10％时,其复合薄膜的拉伸强度达到最大值,光催化降解能力最优,并且样品薄膜的光催化降解符合准一级动力学方程.随着超声时间的延长,样品薄膜的亲水性变差,但其仍为亲水性薄膜,光催化降解率先增后减,且当超声时间为3h时,光催化降解率达到最大值.     

沉积纳米TiO2复合纳米纤维膜的制备及表征

以静电纺丝法和磁控溅射技术制备了负载TiO2纳米颗粒的聚甲基丙烯酸甲酯(PMMA)/蒙脱土(MMT)复合纳米纤维膜,通过光催化降解亚甲基蓝分析比较了不同溅射功率处理的纤维膜的光催化性能,应用电子显微镜(SEM)研究分析溅射功率对纤维形貌的影响以及光催化前后纤维表面形貌的变化.结果表明:经100W和120W功率处理的纤维...     

Fe3+/TiO2改性PVDF中空纤维催化膜的制备及表征

通过干-湿相转化法制备Fe3+/TiO2改性聚偏氟乙烯中空纤维膜,研究了不同聚合物浓度、改性溶胶量、致孔剂对中空纤维膜性能的影响,并对改性后PVDF中空纤维膜的微观结构、膜成分和催化活性进行了测试.结果表明:随着聚合物浓度的增大,中空纤维膜的水通量减小,截留率增加;改性溶胶的添加,显著提高了膜的亲水性和孔隙率,但机械性能有所降低;添加无水LiCl形成的孔多为网络状孔;高分子致孔剂有助于成指状孔,且水通量、截留率都有很大改善.Fe3+/TiO2/PVDF膜有较强的催化过氧化氢的能力.     

PVDF/TiO2@Ag杂化纤维膜的制备及光催化性能研究

采用静电纺丝和光化学沉积法制备聚偏氟乙烯(PVDF)/TiO₂@Ag杂化纤维膜，并通过扫描电镜(SEM)、X射线衍射(XRD)和紫外分光光度计等对复合粉体的微观形貌、晶体结构和光催化性能等进行测试与分析。结果表明：TiO₂的加入能够改变PVDF/TiO₂杂化纤维膜的微观形貌，增加纤维膜的粗糙度。当TiO₂添加量为30%时，PVDF/TiO₂杂化纤维膜的断裂强度和光催化降解能力均达到极大值。PVDF/TiO₂@Ag杂化纤维膜的光催化降解能力随着光化学沉积Ag时间的延长呈现先增后减的趋势。在光化学沉积时间为3min时光催化降解能力最强，且Ag的沉积能实现PVDF/TiO₂@Ag杂化纤维膜在可见光下的光催化降解。     

静电纺丝法ZrO_2/PVDF-PAN超级电容器隔膜的制备及其电化学性能

采用静电纺丝法,以聚偏氟乙烯(PVDF)和聚丙烯腈(PAN)为基体,通过改变ZrO_2的含量,制备了ZrO_2/PVDF-PAN复合纤维膜。用SEM和比表面积测试仪(BET)分别对复合纤维膜的形貌和比表面积进行了表征。结果表明:纳米ZrO_2的加入量对ZrO_2/PVDF-PAN复合纤维膜的形貌有较大影响,随着纳米ZrO_2含量的增加,纤维表面变得凹凸不平,提高了纤维膜的比表面积,进而提高了纤维膜的吸液率,且当ZrO_2含量为PVDF和PAN总质量的0.4%时达到最大值。将复合纤维膜组装成超级电容器,利用电化学工作站对其循环伏安(CV)和交流阻抗(EIS)性能进行测试,研究了ZrO_2的加入对复合纤维膜电化学性能的影响。结果表明:ZrO_2的加入提高了ZrO_2/PVDF-PAN复合纤维膜的电导率,当ZrO_2含量为0.4%时其电化学综合性能最好,其中比容量达126.0F/g,离子电导率为9.31×10~(-3) S/cm。     

强吸附性负载TiO2光催化剂的制备及性能研究

以粉煤灰微珠为载体,基于溶胶-凝胶法制备了强吸附性TiO2负载膜光催化剂,通过XRD、SEM技术对粉煤灰微珠负载TiO2光催化剂的晶型结构和形貌进行了表征,以偶氮染料甲基橙为降解对象,负载层数以及负载量对TiO2光催化活性的影响.结果表明改良溶胶-凝胶法负载的TiO2薄膜催化剂的催化活性最高,同时负载的薄膜催化剂的催化活性明显高于TiO2粉末催化剂.     

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)。