小角散射法测定纳米粉末粒度的比对实验

对纳米粒度的检测是纳米技术领域的重要研究内容之一。不同实验室之间的小角散射测试比对有助于了解和掌握目前国内对纳米级颗粒的检测能力和检测水平。本次比对实验共有9家单位的10台仪器参与,实验结果表明利用X射线小角散射法测量纳米粒径是可靠的,参与比对的各实验室目前的检测水平完全可以为相关科研单位或生产厂家提供准确可信的纳米粒度检测结果。本次比对实验也为各单位进一步提高对纳米粒度的检测能力和完善对纳米粒度检测手段和方法提供了依据。     

电镜法测量纳米材料粒度的比对实验

对纳米材料粒径的检测是表征和研究纳米材料及相关产品性能的重要手段之一。不同实验室之间的测试比对将有助于了解和掌握目前国内对纳米材料粒径的检测能力和水平。本次比对实验采用电镜观察的方法,得到了27台包括扫描电镜和透射电镜在内的不同型号的电镜的测试结果,并利用Z比分数进行评价。结果表明,电镜方法具有可行性;参与比对的实验室目前的检测水平基本可以为相关科研单位或生产厂家提供较准确可信的颗粒粒径尺寸检测结果。     

几种常见粒度分析方法的比对研究

正一、概述颗粒的粒度分析方法很多。随着科技的进步,有些方法被逐步淘汰,有些方法得到了改进和发展(如激光衍射法、动态光散射法等),并在生产和科研中得到了广泛应用(如激光衍射法、显微图像法、电阻法、光透沉降法、筛分法等)。本文选择了目前常见的激光衍射法、显微图像法、电阻法、光透沉降法4种不同测量原理的粒度分析方法,邀请国内实验室合作进行比对实验,对粒度分布范围在(1~100)μm的玻璃微珠颗粒进行粒度分析,对各类统计粒径进行数据比对,以验证这几种粒度分析方法的一致性与可比性。     

氮气吸附BET法测定纳米材料比表面积的比对实验

本文通过9家单位的10台不同型号的仪器,选用氮气吸附BET法,对纳米材料比表面积的检测,实验结果表明该方法可行,参与比对实验室目前的检测水平基本可以为相关科研单位或生产厂家提供较准确的比表面积检测结果。本次比对实验也为各单位进一步提高比表面积的检测能力提供了依据。     

上海首次纳米材料粒径检测比对达到国际先进水平

为确保纳米材料检测数据的准确、可靠和量值统一,上海首次在纳米水平上进行颗粒粒度的检测比对研究取得好成绩。该成果经上海市科技情报研究所水平检索结论为“达到同类研究国际先进水平”。 该项研究是上海市纳米科学技术与产业发展促进中心下达给上海科汇高新技术创业服务中心专项研究项目“上海纳材料测试服务体系的建设(首期)”(编号No.0159nm079)的内容之一。比对协调实验室在50nm、100nm和200nm三个尺度上科学合理地制订了比对方案,按ISO13321《粒度分析光子相关光谱法》标准方法,对标准聚苯乙烯微球悬浮液单分散体系,组织上海交大分析测试中心、华东理工大学分析测试中心、上海材料研究所检测中心、上海市计量测试技术研究院和上海纳米材料孵化基地历时半年,于2002年12月共同完成强度平均粒径的比对测量,结果表明实验室的测量平均值与标准物质的标准值在1.8％以内相符合,实     

上海首次纳米材料粒径检测比对达到国际先进水平

为确保纳米材料检测数据的准确、可靠和量值统一 ,上海首次在纳米水平上进行颗粒粒度的检测比对研究取得好成绩。该成果经上海市科技情报研究所水平检索结论为“达到同类研究国际先进水平”。该项研究是上海市纳米科学技术与产业发展促进中心下达给上海科汇高新技术创业服务中心专项研究项目“上海纳米材料测试服务体系的建议 (首期 )”(编号No .0 15 9nm0 79)的内容之一。比对协调实验室在5 0nm ,10 0nm和 2 0 0nm三个尺度上科学合理地制订了对比方案 ,按ISO1332 1《粒度分析光子相关光谱法》标准方法 ,对标准聚苯乙烯微球悬浮液单分散体…     

动态光散射检测的互信息函数分析方法

互信息函数反映的是系统中的非线性关联,是将线性的关联函数对非线性系统的一种推广,动态光散射领域目前未见到用计算互信息函数进行分析的报道.本文中通过计算互信息函数,对动态光散射检测电机转速的时间序列进行分析,研究表明,互信息函数法能准确地测出电机转速.同时,由于互信息函数自身的优点--能实际地反映出数据之间的相互关联,因此,与自相关函数法比较,互信息函数法反映出了更多的动力学信息.目前正在把互信息函数分析法用于检测颗粒粒径的实验当中.希望利用互信息函数分析的方法,在动态光散射检测颗粒粒径的实验当中得到更多的动力学信息.并进一步应用于纳米颗粒粒径的动态光散射检测中.     

塑料薄膜阻隔性能检测能力现状

阻隔性能检测应用范围广泛,LABTHINK兰光2014年春季塑料薄膜阻隔性能实验室间比对以塑料薄膜为试样,对现阶段的阻隔性能检测水平进行验证。通过对结果的统计分析,可以看出,现阶段我国塑料薄膜阻隔性能整体检测水平尚属理想,但是检测结果仍具有一定的离散性,部分实验室可疑或离群。在目前阻隔性能检测缺乏统一校准规范的情况下,建议实验室积极进行实验室间数据比对,以使自身实验室数据保持在合适的水平。     

表面效应对动态光散射纳米粒径测量的影响

为探究表面效应对动态光散射法测量纳米粒度的影响,设计一种宽度可调的样品池,采用基于高速线阵CCD的动态光散射测量系统,对不同粒径的标准SiO_2颗粒进行测量。结果表明:样品池宽度小于1.3 mm时,粒径测量值随通道宽度减小线性增大,宽度为0.6 mm时,粒径测量值与自由空间中的测量值差距超过5%;样品池宽度较小时,颗粒布朗运动受到明显影响,动态光散射仪中使用微量样品池时,应根据样品池宽度对测量结果进行修正。     

纳米颗粒定向运动对动态光散射测量结果的影响

为探究溶液定向运动对动态光散射测量结果的影响,采用动态光散射测量系统对不同流速下的纳米颗粒进行测量。结果表明:当定向运动速度矢量与散射矢量垂直时,自相关曲线基本不变;当定向运动速度矢量与散射矢量呈某一夹角时,流速越大,自相关曲线衰减越快;在某一特定运动速度下,夹角越小,相关曲线的衰减越快;用有限入射光束宽度下的动态光散射理论可解释上述实验结果。     

纳米粒子气溶胶分析系统的建立

纳米粒子气溶胶分析系统对粒径测量的量值可溯源到标准粒子,可进行单分散、多分散样品的测量以及电子分级筛选。该文介绍纳米粒子气溶胶分析系统的基本原理、测量方法和系统组成,总结了所进行的实验研究。并展望了良好的应用前景。     

基于FPGA高速信号采集的多角度动态光散射法纳米粒径测量

根据动态光散射装置测量纳米粒径原理,开发了一套基于现场可编程门阵列(FPGA)的纳米粒径测量系统。该系统通过光电倍增管(PMT)输出光子脉冲信号,利用FPGA实现高速脉冲采集及自相关运算,采用双脉冲计数器实现高精度可控的连续计数,并实现DDR3异步存储以及USB通信交互等接口功能。自研板卡既可实现自相关函数实时采集运算,又可无丢失地保存海量原始数据信号。采用该系统对200nm聚苯乙烯颗粒进行了测量,分析了不同采样时间及延迟时间等参数对粒径测量结果的影响。实验结果表明:自研FPGA采集板卡测量重复性为1.2%,具有很好的稳定性和重复性。     

Validation of dynamic light scattering and centrifugal liquid sedimentation methods for nanoparticle characterisation

A variety of techniques exists to analyse the size and size distribution of nanoparticles in a suspension. However, these nanoparticle characterisation methods have been rarely fully validated and appropriate reference materials with properly assigned SI traceable values are not easily found. This paper presents results of in-house validation studies of Dynamic Light Scattering (DLS) and Centrifugal Liquid Sedimentation (CLS) methods. During these studies, a silica nanoparticle reference material was tested under repeatability and intermediate precision conditions. The trueness of the DLS and CLS methods was investigated by measuring gold and polystyrene nanoparticle reference materials. Furthermore, for each method, an uncertainty budget has been established. Both method validation and estimation of reliable measurement uncertainties are prerequisites for the certification of new nanoparticle reference materials.     

Influence of sampling rate on the precision for particle size by dynamic light scattering with analog detection

A dynamic light scattering (DLS) experimental system has been set up to study the influence of the sampling rate on the precision of monodispersed particle sizing. Several different parameters relating to the measurement, such as the sampling rate, the number of the correlation channels, the storage depth, and the lag time, are selected to execute the DLS measurement. The experimental results obtained in different cases are reported, and the influences of the sampling rate on particle sizing are also discussed. From the results and discussion it can be seen that the sampling rate plays an important role in the measurement of the particle size. The variety of the sampling rate can lead to the presentation of different correlation functions and then different precision levels for the particle size. In conclusion, a suitable sampling rate is presented to direct the measurement of test particle size.     

Determination of the size of water-soluble nanoparticles and quantum dots by field-flow fractionation

Field flow fractionation (FFF) technique is used to determine the size of water-soluble Au, ZnS, ZnS-Mn2+ nanoparticles, and CdSe, CdSe-DNA quantum dots (QDs). The results of the FFF measurements are compared with the particle size analysis using conventional techniques like scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) studies. Water-soluble gold nanoparticles (AuNPs) stabilized by mercaptosuccinic acid (MSA) as the ligand when analyzed by the SEM and DLS showed evidence of extensive aggregation, preventing an accurate determination of the average particle size. The TEM analyses without staining offered a facile measurement of the nanoparticle core but average particle size determination required analysis of the TEM image using image analysis software. On the other hand the FFF is seemingly a convenient and easy method for the determination of the average particle size of the AuNPs. In case of the ZnS and ZnS-Mn2+ nanoparticles with mercaptopropionic acid (MPA) as the capping agent severe aggregation prevented accurate estimation of particle sizes even by the high resolution TEM (HRTEM), where as the size determination by the FFF was very facile. Analysis of the CdSe-DNA conjugate by the TEM was difficult as the sample got damaged upon exposure to the electron beam. The FFF cross-flow condition is apparently noninvasive and hence the technique was very effective in characterizing the CdSe-DNA QDs. Furthermore, using this simple technique it was possible to fractionate a sample of the AuNPs. The FFF measurement of water-soluble nanoparticles is an excellent complement to characterization of such particles by the conventional tools.     

Determination of particle size distributions and the degree of dispersion in nanocomposites

Objective of this study was the investigation of measurement techniques to determine the quality of the dispersion process of nanoparticles in polymer composites. In order to prepare the matrix suspension, alumina nanoparticles were dispersed applying shear mixing techniques in a high performance laboratory kneader. The product quality in liquid state was determined by means of dynamic light scattering (DLS) and centrifugal sedimentation analysis (CSA). However, particle measurements in carrier fluids like epoxy resin are complex and challenging. Measuring values like particle size distribution and grade of homogeneousness are strongly influenced by the sample preparation and adjustments of the measuring device. Within this study the machine settings and the formulation was analysed systematically. Hereby an identification of the key parameters and an optimisation of the measuring process were possible. Additionally, the composite was cured and analysed by scanning electron microscopy (SEM). Finally all measuring techniques were evaluated and compared among each other. Thus, DLS is the fastest method to measure spherically particles in the liquid matrix, CSA allows a certain deviation from the spherical shape and SEM gives a qualitative impression of the final particle size in cured composite condition.     

An on-line measurement and control system for submerged arc spray synthesis of TiO2 nanoparticles

This article presents the development of an on-line measurement and control system for process characterization and optimization of the nanoparticle manufacturing process, called the submerged arc-spray nanoparticle synthesis system (SANSS). To achieve optimized control of particle uniformity, this research investigates the feasibility of employing optical fiber probe and the dynamic light scattering (DLS) technique to monitor and control particle sizes. According to the theory of DLS, an on-line nanoparticle sampling and measurement system was developed and integrated with the SANSS as an important step to verify the measurement performance of the proposed method. To examine the measurement accuracy of the developed system, calibrated polystyrene latex particles with known accurate sizes were employed to verify the particle sizing accuracy of the proposed system. The data conformity between the measurement results of TiO, nanoparticles obtained by various methods, including TEM, a calibrated commercial particle sizing system and the on-line measurement system, has indicated that the developed method was feasible and effective.     

Application of dynamic light scattering to the study of small marine particles

Small particles ranging from approximately 0.1 μm to several micrometers in size, which include detrital material, bacteria, and other planktonic microorganisms, make a significant contribution to light scattering in the upper ocean. The scattering properties of these particles are strongly dependent on their size, which is difficult to measure in the submicrometer range with commonly used electronic resistive counters and microscopic techniques. We examined the size of small marine particles by application of the dynamic light scattering (DLS) method. In this method the time-dependent autocorrelation function of scattered intensity by particles undergoing Brownian motion provides information about the size of particles. The samples were collected in clear oceanic waters off the coast of Southern California. The mean hydrodynamic diameter of particles, determined from the DLS measurements at a scattering angle of 45°, was 0.54μ m. This indicates that the major contribution to scattering at this angle comes rom submicrometer particles. We also described an inverse method for estimating the general slope of the size distribution of small marine particles from the mean hydrodynamic diameter. This method is based on calculations of the size distribution weighted by distribution from Mie theory and assumes that a power-law approximation represents the actual particle scattered intensity. These calculations suggested that particulate assemblage in our seawater samples was best characterized by a differential size distribution with a slope of -4.35. This estimation was supported by independent measurements of particle size distribution and the spectral beam attenuation coefficient taken from the same samples as those used for the DLS measurements. We also demonstrated that multiangle DLS measurements may be used to determine the representative value of the refractive index of particles.     

Comparative Nanoparticle Size Characterization of EEW Alumina Using Various Measurement Techniques

Modern material science is paying more attention on the development of nanomaterials for superior properties in various fields of applications like mechanical, thermal, electronic, bio-medical etc. For such applications, determination of nanoparticle sizes along with their distribution is important for attaining the desired properties. Particle sizes along with the crystallite sizes of oxides, non-oxides and metallic nanopowders produced by different processes can be determined by different techniques which includes x-ray diffraction/neutron diffraction (XRD/ND), transmission electron microscopy/field emission scanning electron microscopy (TEM/FESEM), Brunauer-Emmett-Teller (BET) surface area method, small angle neutron scattering (SNAS), dynamic light scattering (DLS), static light scattering (SLS), etc. For average nano-metric particle size determination, DLS is the most frequently used technique that gives a distribution that approximates the exact binomial distribution of large numbers of nanoparticulates with varying particle size under investigation (Gaussian distribution). However, the other techniques mainly give either localized distribution of the particles under observation or the distribution derived from type II isotherm. In this investigation, nano-alumina powder produced by the electrical explosion of wire technique (EEW) is used for comparative evaluation of particle size analysis by DLS measurement technique for nanoparticles vis-à-vis to other techniques like XRD (for crystallite size), FESEM, BET, and TEM. The superiority of the DLS technique has been discussed in details with respect to the unique features of its Gaussian distribution nature.     

超声法纳米颗粒悬浮液粒径测量中温度影响的实验研究

针对医药、化工领域高浓度纳米悬浮液颗粒粒径超声检测中温度影响,采用超声衰减谱法(UAS)对体积浓度30%的纳米铟锡金属氧化物(ITO)水性悬浮液在循环流速800 r/min,温度298～358 K时颗粒粒径分布进行实验。结果表明:温度升高,超声幅值A减小,超声衰减系数增大,颗粒中位径D50增大,颗粒系分布曲线整体朝大颗粒方向偏移,但是分布宽度保持稳定的趋势。同时,将室温(298K)测量结果与CPS离心沉降颗粒测量仪对比,结果较吻合。通过线性回归的方法修正温度对测量结果的影响,超声衰减法能够应用于358K的高温下高浓度纳米颗粒检测。