准弹性激光光散射法(续)

三、准弹性激光散射技术仪器说明3—1 小角激光光散射光度计下面以美国 LDC/Milton Roy 公司生产的小角激光光散射仪 KMX—6/DC 为例子进行说明。应用于准弹性激光光散射技术测量的KMX/6 DC 仪是在原有小角激光光散射光度计 KMX—6的基础上对两个主要部件进行了改进而完成的,其余的仪器光路设计是一样的。     

激光光散射法测定粒度在陶瓷行业中的应用

本文介绍了激光光散射法测量粒度的原理,以及激光粒度分析仪的特点,并探讨了激光光散射法测量粒度在陶瓷生产中的应用。     

准弹性激光光散射法(一)

本刊将从今期开始分四期连续刊登中山大学梁国眉、冯榕荫同志的“准弹性激光光散射法”一文。本文所介绍的动态光散射技术(又称为准弹性光散射技术)是近十多年来世界才发展起来的新研究和新技术。它使用激光光源,用光子相关光谱对合成高分子、生物大分子、胶体溶液的动态扩散系数、大分子运动形态和流体力学尺寸进行测定,不仅是准确而快速的测量方法,而且对上述各种溶液性质研究也是十分有用的工具。本文介绍了这一技术的原理、仪器结构及应用说明,希望大家能从该文中对此项新技术有所认识。     

光散射技术及其在高分子溶液研究中的应用

从重均分子量,均方旋转半径及平均扩散系数等高分子溶液中较为重要的几个物理量入手介绍了近十几年来光散射技术在高分子溶液领域的应用。同时,对静态光散射和动态光散射的几个重要参数以及其较为重要的公式也做了介绍。最后,还综述了光散射的发展简史、基本原理、有关实验的技术方法等内容。     

在DMSO水溶液中CTAB胶束的粒径分布

利用激光光散射和染色 -电镜技术研究了在二甲基亚砜 ( DMSO)水溶液中十六烷基三甲基溴化铵 ( CTAB)胶束的粒径分布以及粒径分布、聚集数和扩散系数等受 KBr浓度的影响和随时间的改变     

激光光散射法测定PNIMMO的相对分子质量及其分布

介绍了火药用黏合剂PNIMMO(端羟基聚3–硝酸酯甲基–3–甲基氧杂环丁烷)的相对分子质量及其分布测定的激光光散射法。该法以四氢呋喃为流动相,通过MZ–gel SD plus凝胶色谱柱、示差折光检测器与多角激光光散射仪联用,获得了样品的相对分子质量及其分布,并对谱图进行分析讨论。结果显示,激光光散射法不依赖于标样,可直接测定PNIMMO的相对分子质量及其分布,快速简便,结果可靠,对于PNIMMO合成工艺的改进和后处理方法的选择具有指导意义。     

聚丙烯/橡胶共混体系——聚丙烯顺丁橡胶改性的研究(Ⅱ)

在等规聚丙烯中掺混高顺式聚丁二烯橡胶,研究了顺丁橡胶改善等规聚丙烯脆性的效果,测定了加入不同比例橡胶的共混物的强度。应用激光小角光散射Hv散射强度分布观察并确定了聚丙烯的结晶变化及形态,计算了球晶尺寸,同时绘出了Vv散射强度图。     

聚合物流动行为的光散射表征

简要地介绍了光散射原理及目前光散射技术在聚合物流变学的中的应用，归纳并分析了前人的一些主要工作成果。对于一些至今难以解释的实验现象提出了自己的一些认识，并对仍未有人涉足的振动力场下聚合物复杂流动光散射表征提出了新的设想。     

甲基丙烯酸丁酯—苯乙烯共聚物分子量的测定—粘度法

高聚物分子量测定方法很多,如端基分析法;等温等压蒸镏法;冰点降低法;沸点升高法;蒸汽压渗透(VPO)法;光散射法;激光光散射;超速离心法;凝胶渗透色谱法等。考虑到所研制的高聚物,在应用中要求的分子量范围,以及实验室所具备的测试条件,采用粘度法,该方法简便,应用极广,是目前国内最常用的测定方法。     

激光衍射散射式测粒技术在聚氯乙烯糊树脂粒径分析中的应用

介绍了激光衍射散射式测粒技术在聚氯乙烯糊树脂(PPVC)粒径分析中的应用情况,讨论了实验条件的优化。结果表明:激光衍射散射式测粒技术的可测粒径范围广、测量过程快速、测量结果准确,能准确地测量具有双峰分布的样品,是测量和表征PVC乳液颗粒粒径及粒度分布的理想方法。     

激光散射在生物高分子中的应用

本文综述了激光散射在生物高分子中的应用,着重以蛋白质为例分析了激光散射在表征生物高分子的分子量、尺寸、构象、缔合、聚集、结晶和分形等方面的重要作用,同时对它在生理分析上的应用作了简要介绍。     

Optical Detection of Particle Contamination on Surfaces: A Review

This paper reviews the application of light scattering to the detection and measurement of discrete contaminating particles on smooth surfaces. The optical properties of specular and diffuse reflecting surfaces, and those of isolated particles are summarized, followed by the behavior of surface-deposited particles. A discussion is presented on the parameters influencing the detectability of particles on surfaces, and the principal design criteria of light scattering inspection systems. Emphasis is placed on laser scanning systems which, at present, predominate as a versatile means of automated surface contamination detection. Both laser scanning and video inspection systems are discussed, and examples are presented of typical commercially available instruments incorporating these techniques.     

Characterization of enzymatically synthesized amylopectin analogs via asymmetrical flow field flow fractionation

Asymmetrical flow field flow fractionation (AF4), when coupled with multi-angle laser light scattering (MALLS), is a very powerful technique for determination of the macromolecular structure of high molar mass (branched) polysaccharides. AF4 is a size fractionation technique just as size exclusion chromatography (SEC), nevertheless can overcome some crucial problems found in SEC analysis especially in starch like structures. This paper describes a detailed investigation of the macromolecular structure of two groups of well-defined synthetic amylopectin analogs – synthesized via an in vitro enzyme-catalyzed reaction using the enzymes phosphorylase b from rabbit muscle and Deinococcus geothermalis glycogen branching enzyme (Dg GBE). Size, molar mass distributions and structural data were studied by AF4 coupled with online quasi-elastic light scattering (QELS) and multi-angle light scattering (MALLS).     

Development of an ultraviolet constant angle Mie scattering detector toward the determination of aerosol growth kinetics in the transition and free molecular regime

Abstract

The measurement of aerosol growth kinetics at ever smaller sizes toward the transition and free molecular regime is of interest to provide for validation of theoretical predictions. Such measurements remain challenging to accomplish, particularly those occurring in the kinetic regime. Toward this goal, an instrument based on the ultraviolet constant angle Mie scattering (UV-CAMS) method was developed. The instrument utilizes adiabatic expansion to cause supersaturation and drive aerosol growth. Aerosol particles growing by water condensation are illuminated with a pulsed UV laser at 337?nm wavelength and a reference laser with red light (wavelength of 632?nm). The scattered light fluxes at 30° are measured simultaneously and are then compared with size resolved Mie scattering calculations providing aerosol growth measurements. The growth curves obtained from UV match those from the red laser. These measurements allow us to see the first Mie peak for UV scattering for particles in the 500?nm range. This is an almost two-fold resolution increase compared to the smallest particles that can be seen via red laser scattering in similar conditions (first Mie peak above 900?nm).     

A Novel Method for Estimating Light-Scattering Properties of Soot Aerosols Using a Modified Single-Particle Soot Photometer

A Single-Particle Soot Photometer (SP2) detects black refractory or elemental carbon (EC) in particles by passing them through an intense laser beam. The laser light heats EC in particles causing them to vaporize in the beam. Detection of wavelength-resolved thermal radiation emissions provides quantitative information on the EC mass of individual particles in the size range of 0.2–1 μm diameter. Non-absorbing particles are sized based on the amount of light they scatter from the laser beam. The time series of the scattering signal of a non-absorbing particle is a Gaussian, because the SP2 laser is in the TEM00 mode. Information on the scattering properties of externally and internally mixed EC particles as detected by the SP2 is lost in general, because each particle changes size, shape, and composition as it passes through the laser beam. Thus, scattered light from a sampled EC particle does not yield a full Gaussian waveform. A method for determining the scattering properties of EC particles using a two-element avalanche photodiode (APD) is described here. In this method, the Gaussian scattering function is constructed from the leading edge of the scattering signal (before the particle is perturbed by the laser), the Gaussian width, and the location of the leading edge in the beam derived from the two-element APD signal. The method allows an SP2 to determine the scattering properties of individual EC particles as well as the EC mass. Detection of polystyrene latex spheres, well-characterized EC particles with and without organic coatings, and Mie scattering calculations are used to validate the method.     

Instrumentation on Multi-Scaled Scattering of Bio-Macromolecular Solutions

The design, construction and initial tests on a combined laser light scattering and synchrotron X-ray scattering instrument can cover studies of length scales from atomic sizes in Angstroms to microns and dynamics from microseconds to seconds are presented. In addition to static light scattering (SLS), dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD), the light scattering instrument is being developed to carry out studies in mildly turbid solutions, in the presence of multiple scattering. Three-dimensional photon cross correlation function (3D-PCCF) measurements have been introduced to couple with synchrotron X-ray scattering to study the structure, size and dynamics of macromolecules in solution.     

Compared molecular characterization of hyaluronan using multiple-detection techniques

The biological functions as well as physico-chemical properties of hyaluronan (HA), one of the most important and ubiquitous glycosaminoglycan in various organisms, are closely related to its molecular weight, molecular weight distribution and chain conformation. For this reason it is crucially important to make a reliable characterization of these parameters for HA in both chemical and clinical fields. The present work compared the application of different techniques including capillary viscometry, concentration gradient multiangle laser light scattering (CG-MALLS), size exclusion chromatography-multiangle laser light scattering (SEC-MALLS), asymmetric flow field flow fractionation-multiangle laser light scattering (AFlFFF-MALLS) and horizontal agarose gel electrophoresis (AGE), to the characterization of a range of HA samples of bacterial and animal sources. The advantage and limitation of these techniques were discussed in terms of producing accurate and reliable molecular parameters.     

聚对苯二甲酸丁二酯(PBT)球晶形态结构和取向的研究

本文用小角激光散射仪和偏光显微镜观察了PBT的球晶形态。由于结晶条件不同而产生寻常球晶和非寻常球晶。与PET比较可知,由于其分子结构的少许差异,而使球晶形态受到很大影响,PBT和PET纤维的双折射率都随纺速的提高而增大,但在同一纺速条件下PBT纤维的双折射率要高得多。