Mie scattering from sphere structures in polymer blends

Polymer blends of transparent poly(methyl methacrylate) and polystyrene become opaque due to light scattering at the boundaries of the two polymers. The polymer blend is light brown when it is illuminated by white light. The coloring depends on the spherical domain structures existing in the polymer blend. The coloring was analyzed by using the rigorous Mie theory. The Mie results were compared with the semiempirical results previously reported by the authors. The wavelength dependence of theoretical scattering efficiencies on radii of scattering spheres from 0.05 to 1.2 μm was obtained for polystyrene spheres in poly(methyl methacrylate) matrix, and vice versa. The scattering at the short wavelength region is stronger than at the long wavelength region. The scattering efficiencies become almost constant in the visible wavelength region for sufficiently large spheres.     

Computations of the Mie scattering coefficient corrected for the forward scattering

Computations of the actual Mie scattering coefficient (K_a) have been performed by taking into account the acceptance angle (₀) of the optical receiving system. Results show that in problems concerning the determination of the aerosol particle parameters through scattering methods, the total scattering coefficient (K_r) computed by taking ₀ = 0 has to be substituted by K_a. Tables of K_a have been arranged for the following values of the particle refractive index (m), size parameter (x) and ₀: M = 1·33, X = 0·1 (0·1) 200 and m = 1·55, X = 0·1 (0·1) 100, for ₀ = 0·1° (0·1°) 1·0°.     

A flowsheet drawing program for a visual display computer

A program for a visual display computer is described which enables a user to ‘draw’ pictures closely resembling chemical plant flowsheets. It is thought that this approach could be useful as a means of introducing the problem structure into the computer and also as a visual aid for the user. Specifications are described which were laid down for this new program and which were formulated as a result of experience gained with a previous more general network drawing program. An account is given of the major problems which arose in the implementation and the solutions which were adopted.     

CAEv–A program for computer aided evaluation

The evaluation of new reagents and instruments in clinical chemistry leads to complex studies with large volumes of data, which are difficult to handle. This paper presents the design and development of a program that supports an evaluator in the definition of a study, the generation of data structures, communication with the instrument (analyser), online and offline data capture and in the processing of the results. The program is called CAEv, and it runs on a standard PC under MS-DOS. Version 1 of the program was tested in a multicentre instrument evaluation. The concept and the necessary hardware and software are discussed. In addition, requirements for instrument/host communication are given. The application of the laboratory part of CAEv is described from the user''s point of view. The design of the program allows users a high degree of flexibility in defining their own standards with regard to study protocol, and/or experiments, without loss of performance. CAEv''s main advantages are a pre-programmed study protocol, easy handling of large volumes of data, an immediate validation of the experimental results and the statistical evaluation of the data.     

Enhancement of the Mie scattering effect using floatstone-like TiO2 spherical micropigment

Floatstone-like TiO₂ microparticles with an efficiently enhanced Mie scattering effect were developed by thermofusing of rutile-type TiO₂ submicron particles on the template core of poly(acrylate) microspheres. The light reflectance of the floatstone-like TiO₂ microparticles was approximately 10% higher than that of the usual rutile-type TiO₂ submicron particles in a wavelength range from 400 to 850 nm. The diffuse reflectance of the microparticles is enhanced by the formation of a floatstone-like structure, whereas there is no difference in the specular reflectance of the particles. As an application of the floatstone-like TiO₂ microparticles, the contribution of the particles to the light-trapping effect of a solar cell was examined. The power conversion efficiency of the solar cell was enhanced by 22% with the introduction of a light-scattering layer composed of the floatstone-like TiO₂ microparticles.     

Measurement of aerosol size distribution function using Mie scattering—Mathematical considerations

This paper analyzes the applications of Mie scattering to measure the size distribution function (SDF) of aerosols. Measurement of SDF by Mie scattering usually involves solving the Fredholm integral equations of the first kind based on discrete inputs with uncertainties (e.g., extinction measurements at multiple wavelengths or at multiple angles). A set of inputs which are not mutually independent within the measurement error implies that redundancy exists in the measurements and not all the measurements provide useful information for solving the integral equations. To avoid such redundancy, this paper develops a method to analyze the dependency among the kernel functions associated with Mie scattering. Applications of this method are demonstrated and the results provide valuable insights into the optimization of SDF measurement based on Mie scattering, in terms of minimizing the number of measurements needed and revealing the optimal wavelengths and angles to perform the measurements.     

A personal computer software program for coathanger die simulation

A good extrusion die must distribute the polymer melt in the flow channel such that the material exits from the die with a uniform velocity and temperature. Coathanger dies are commonly used for the extrusion of plastic sheets and films. The die is usually provided with a straining bar allowing a regulation of the flowrate in the case of a poor design. But this, in turn, can affect temperature uniformity. Therefore, the design of coathanger die is a complex task which is mainly accomplished by trial and error in industry. Analyses of the flow in coathanger dies have been reported in the literature. Analytical and numerical approaches are used to solve this problem. The first one involves many simplifying assumptions: the most important ones being the unidirectional and isothermal flow of the polymer. Most numerical methods deal with a 2-D geometry, but only a few of them have considered the non-isothermal flow. A new model has been developed using a modified FAN method (Flow Analysis Network introduced by Tadmor) for the calculation of the 2-D flow, coupled with a finite-difference scheme for the calculation of temperature. The overall model can run on a PC with only a few minutes of calculation. Good agreement was obtained between experimental data and simulations.     

辐射悬浮聚合制备球状吸水树脂

采用60Co-γ射线辐射引发淀粉-丙烯酸静置悬浮聚合,制备了粒径250～850 μm左右的球状吸水树脂.考察了剂量率、剂量对高吸水树脂吸液性能的影响,并对球状吸水树脂进行了表面处理,结果表明,球状吸水树脂通过表面处理后,大大提高了吸液速率.     

立式储罐球面顶板放样

由于立式储罐的容积逐年增大,它的顶板厚度也有所加厚,顶板之间的连接也由原来的搭接变为对接。所以对立式储罐球面顶板放样的精度有一定要求,实践证明,利用计算机放样完全可以得以满足。本文介绍一种采用钣金展开放样系统计算机软件的解决方法提供参考。     

PCSP: a computer program to predict and analyze the packing in crystalline polymers

A computational strategy based on force-field calculations was developed to predict and analyze the packing in crystalline polymers. The strategy, which was incorporated in a computer program called Prediction of the Crystal Structure of Polymers (PCSP), takes advantage of the information provided by X-ray and/or electron diffraction. The program evaluates all the modes of packing for a given lattice dimensions, being able to predict the lowest energy one. The ability of the method to provide reliable results was proved by analyzing the crystal structure of four different polymers. Further, an insight on the applicability of the PCSP program to estimate the mechanical properties of polymers was provided by computing the elastic constants of the orthorhombic polyethylene.     

Analysis method of explosive electromagnetic radiation energy

The energy of electromagnetic radiation from explosions is coupled to electronic equipment circuits, disrupting the initiation sequence or causing failure in an increasing number of cases, which seriously affects the stability of weapon systems. There is a significant difference between the characteristics of the explosive electromagnetic radiation signals and modulated electromagnetic signals. The electric field intensity and signal power cannot directly represent the magnitude of the explosive electromagnetic radiation energy, and traditional electromagnetic signal analysis methods are unsuitable for explosion electromagnetic signal analysis. To solve this problem, the mechanism of explosive electromagnetic radiation was first analyzed. Through verification experiments of the explosion electromagnetic intensity and temperature, it was concluded that there is a strong correlation between the explosion plasma temperature and electromagnetic intensity. The temperature of the explosive plasma is derived based on the measured surface temperature of the explosive fireball, a functional relationship is established between the energy of the explosive plasma and the temperature of the plasma, and plasma energy is introduced as a parameter for electric field intensity correction. The interference signal analysis method based on eye diagram is used to calibrate the electromagnetic radiation damage ability, achieving quantitative analysis of the interference degree of electromagnetic radiation energy on the signal, and providing a new approach for the analysis of explosive electromagnetic radiation energy.     

A versatile digital computer program for the analysis of gel permeation chromatograms

Gel Permeation Chromatography (GPC) has found application not only in the study of the molecular weight distribution of high polymers but also in the separation of oligomers and other low molecular weight compounds. This paper describes a computer program which deals both with the analysis and resolution of a get permeation chromatogram of an oligomeric mixture into its component peaks and with the evaluation of the molecular weight distribution of high polymers. Several refinements built into the program allow the use of input data from either a spectrophotometer or a differential refractometer, and permit the calculation of errors caused by a linear shift in the calibration curve. The program can also be adapted readily to curve resolution problems in other fields.     

A computer simulation study of the low-angle x-ray scattering obtained from triblock copolymers

Computer programs were developed to produce graphic plots which simulate the lowangle x-ray scattering curves obtained from cast films of triblock copolymers. Models were developed to take account of lattice paracrystallinity, a distribution in size of the scattering elements, various types of lattice packing, and the possibility of more than one type of lattice packing in a loosely bound paracrystal. These studies provide an insight into the possible structure of the macrolattices which have been observed with triblock copolymers.     

Digital computer program for calculating selectivities of hydrogenation catalysts

Linolenate and linoleate selectivities of hydrogenation catalysts are determined by a digital computer program which solves the kinetic equations of consecutive first-order reactions. The described program is applicable to any initial oil or degree of hydrogenation.     

Effects of anisotropic scattering of radiation in laminar forced convection in a parallel-plate duct

Effects of anisotropic scattering to heat transfer in hydrodynamically-developed, thermally-developing steady laminar forced flow of a gray fluid between two infinite parallel plates are investigated for the case when the inlet temperature of the fluid is less than the wall temperature. An implicit finite difference scheme is applied to solve the energy equation, while the high order P_N method is used to solve the radiation part of this problem. The effects of the anisotropy, the conduction-to-radiation parameter, the optical thickness, the reflectivity of the plates and the inlet temperature on the local Nusselt number are studied.     

Motions of a sphere in a time-dependent stokes flow: A generalization of Faxen’s law

A general solution of the unsteady Stokes equation in spherical coordinates is derived for flow in the exterior of a sphere, and then applied to study the arbitrary unsteady motion of a rigid sphere in an unbounded single fluid domain which is undergoing a time-dependent mean flow. Calculation of the hydrodynamic force and torque on the sphere leads to a generalization of the Faxen’s law to time-dependent flow fields which satisfy the unsteady Stokes equation. For illustrative purposes, we consider the relative motion of gas bubbles which undergo very rapid oscillations so that the generalized Faxen’s law derived for a solid sphere can be applied. We also demonstrate that our results reduce to those of Faxen for the steady flow limit.