Autoradiographic determination of the di-n-butyl phthalate concentration profile in a nitrocellulose matrix

The concentration profile of a deterrent (di-n-butyl phthalate) which had been diffused into a nitrocellulose sphere (ball propellant) containing nitroglycerin was studied by means of autoradiography. Results indicate a level concentration part way into the sphere with an abrupt dropoff in concentration. An explanation for this type of concentration profile is offered based on hydrogen bonding of the deterrent carbonyl group with unesterified hydroxyl groups in nitrocellulose.     

Diffusion rates and the role of diffusion in solid propellant rocket motor adhesion

Diffusion rates can give important information for the adhesion process across the bondline between insulation and propellant in solid propellant rocket motors. Diffusion coefficients of low molecular weight species such as crosslinkers and plasticizers have been measured by the weight of uptake method in polymer materials that are candidates for propellant contact. The materials were EPDM insulation sheets and “liners,” based on HTPB, HTPE, or GAP, and with different degrees of particle filling. Plots of relative mass gain as a function of the square root of time showed good linearity up to 20–50% weight increase and the diffusion coefficients could thus be determined with good accuracy. The diffusion coefficients for the low molecular weight isocyanates and plasticizers in these materials vary between 10^?11 and 10^?17 m² s^?1, dependent on material types and particle filling. In most cases, the results can be explained by the solubility parameters of the organic liquids and polymers. For the particle filled samples, the diffusion coefficients decrease with increasing degree of particle filling, and the decrease is faster than predicted by the Maxwell–Fricke or the Keller models for arrays of smooth spheres. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1529–1538, 2007     

纳米金属粉的制备、改性及其在推进剂中的应用

综述了纳米金属粉的制备、改性及其在推进剂中的应用,重点介绍了制备金属粉的电爆法。分析了纳米金属粉发展中的瓶颈及问题,指出了未来的发展方向,以为相关纳米材料的发展提供参考。     

图像分析技术在PVC颗粒粒径大小及分布测定中的应用

利用图像分析技术对PVC透射光镜图像进行处理,引入算术平均粒径、质量平均粒径及粒径分布均匀度等参数.考察了最低检测像素数、灰度值阈值、透明颗粒的处理方法等实验条件对测定结果的影响,建立了PVC颗粒粒径大小及分布的表征方法.利用本方法对相同聚合度、不同生产厂家的4个PVC样品的粒径大小及分布进行了对比分析.     

采用凝胶色谱法测定PVC分子质量分布及其在质量管理中的应用

介绍了采用凝胶色谱法分析PVC分子质量分布，分析了PVC分子质量分布对产品质量的影响，指出了凝胶色谱法在PVC质量管理中的重要性。     

Experimental study of residence time,particle movement and bed depth profile in rotary kilns

Experiments were performed in a pilot scale rotary kiln with coal and coke particles to study their mean residence time, residence time distribution, bed depth profile and time spent at the bed surface. The influence of filling ratio on residence time was studied with a uniform bed depth in the kiln. Residence time distribution and bed depth profile measurements were performed in a kiln without end constriction, at different rotational speeds and different solid inputs. The residence time fraction corresponding to the passage of the particles at the bed surface was measured with a photographic study of the movement of a coloured particle. Various equations were tested to represent the experimental results. The equations of Kramers and Croockewit (1952) and Ronco (1965) were adequate to calculate mean residence times, while only the former could represent correctly the bed depth profile. An equation is proposed which turns out to be quite accurate in predicting the fraction of the residence time spent in the upper layer of the bed.     

Comparison between Cottrell diffusion and moving boundary models for determination of the chemical diffusion coefficients in ion-insertion electrodes

Using PITT technique, the various shapes of the Cottrellian diffusion plots, It^1/2 versus log t, were studied as a function of the electrode potential for the Li ions insertion into graphite electrodes. Single maximum appeared on the It^1/2 versus log t plots for stoichiometries close to pure staged phases, whereas two maxima were always observed in the two-phase coexistence domains. Slow nucleation rate during phase 2/phase 1 transition was revealed by the characteristic shape of the initial time domains of both chronoamperometric and chronovoltammetric curves. Corrected for nucleation, the longer time domain of the response was treated chronocoulometrically in the framework of two alternative approaches using the moving boundary and the classical Cottrellian models. The alternative approaches resulted in virtually the same value of D. The diffusion of Li ions during phase 2/phase 1 transition is largerly affected by slow interfacial charge transfer. In this case, the spinodal domain in the free-energy curve is effectively degenerated even at small overvoltages. This substantiates the formal application of the Cottrellian diffusion approach to determine D during the processes of intercalation and deintercalation, accompanied by first-order transitions; however, involvement of the slow interfacial kinetics in the measured response should be adequatly taken into account.     

Direct determination of saturated fatty acids in fats,oils, and methyl esters

Summary A direct gravimetric method has been developed for the determination of saturated fatty acids in fats, oils, and methyl esters. The procedure involves methanolysis of the triglycerides to produce methyl esters, followed by oxidation of the unsaturated methyl esters by potassium permanganate. The undesired, acidic oxidation products are removed by alkaline washing and the saturated methyl esters thus isolated are weighed directly. The method is intended for the determination of saturated fatty acids having C₁₆ or longer carbon chains. Small quantities of C₁₄ saturated acids will be included in the determination if present with other higher saturated acids. The method is applicable to both natural and hydrogenated vegetable oils. It is not applicable to oils containing large amounts of C₁₄ and lower saturated acids. Concentrations of saturated acids ranging from 3 to 90% in known glyceride mixtures and from 0.3 to 95% in mixtures of methyl esters were determined with an average difference from the calculated value of 0.8%. Replicate determinations on samples in the 10 to 30% saturates range gave a standard deviation of 0.3 to 0.4%. Presented at the spring meeting, American Oil Chemists’ Society, New Orleans, La., April 28 to May 1, 1957     

采用凝胶渗透色谱法确定PVC中增塑剂的种类及含量

介绍了采用凝胶渗透色谱（GPC）法确定PVC粒料中邻苯二甲酸酯类增塑剂的具体种类及含量。     

濮城油田深调技术的研究与应用

淮城油田已进入注水开发的后期,在油井含水率不断上升,常规聚合物调剖效果逐渐变差的形势下,开展了深部调剖技术的研究与应用,并取得了满意的效果。     

The use of the logarithmic adsorption isotherm for the determination of the micropore-size distribution

The determination of the micropore-size distribution of microporous materials is of major importance in the field of adsorption and catalysis. This new method to derive the micropore-size distribution for Pillared Clays (PILC) is based on the logarithmic adsorption isotherm.When a N₂-adsorption isotherm is replotted on a log P/P ₀ scale, a curve representing the adsorption potential is obtained. Because the adsorption potential is highly dependent on the pore-size, this curve contains all the information on the pore structure. These curves often exhibit steps, large increases in volume adsorbed by small changes in adsorption potential. These are thermodynamically related to the filling of pores of a certain size. The relative pressures where these steps appear are dependent on the pore-size. Taking the derivative, dV/d log (P/P ₀), the location of these steps becomes more clear. These derivative curves give a lot of information on the pore-size distribution. The presence of several maxima and their sharpness informs about the number of different pore-sizes present and the homogeneity. Assuming that N₂-adsorption in the micropores is ruled by the amount of N₂-layers which can fit in, the micropore range can be subdivided in five pore groups adsorbing 1–5 layers. By locating the main maxima in the derivative curves of pillared clays with known but different slit widths, we can correlate a pore-size range to a certain P/P ₀ range where these pores will fill.In this way a micropore-size distribution based on the adsorption potential can be constructed.     

An integral equation approach for the analysisof current density distribution controlledby diffusion, convection and migration

The present work describes novel numerical formulations based on integral equations for calculating steady-state distributions of concentration, potential and current density in two-dimensional multiple-ion electrochemical systems involving diffusion, convection and migration effects. For simplicity, the electrolyte solutions are considered to be dilute and at a constant temperature. Numerical procedures using the boundary element method (BEM) have been developed specifically for the problem, and are briefly described in the text. The accuracy and efficiency of these procedures are assessed with several tests, involving binary and three-ion systems, linear and non-linear boundary conditions, and problems that are either diffusion- or convection-dominated, or both.     

The application of the equivalent annulus width concept in thermal diffusion separations

The equivalent annulus width concept is used to characterize a small commercial thermogravitational thermal diffusion column and its validity checked experimentally by separating batchwise in the column mixtures of n-heptane—benzene with different initial concentrations. The equation of Ruppell and Coull was used to analyse the data in the short separation times range and determine the equivalent annulus width.

Good agreement was obtained between the experimental and predicted time-separation curves when using the equivalent annulus width value and on averaged value of the thermal diffusion constant. A new method is presented for the simultaneous determination of the equivalent annulus width and the thermal diffusion constant of a binary mixture from a single set of experimental data.     

An application of scattered-light photoelasticity in the determination of the side pressure distribution of the pressed powder bed

Improved photoelastic measurements were applied for the determination of the side pressure distribution of the pressed powder bed on the basis of the principle given in the previous paper. Absolute values of stress components σ_r, σ_θ, σ_z and τ_rz in the container wall were determined from the measurements of three different directions of incidence of the laser beam. By extrapolating the values of σ_r and τ_rz to the inner surface of the container, side pressure components of the powder bed, normal and tangential to the wall respectively, were obtained. Indirect confirmations for the validity of the results were given.     

Concentration dependence of the diffusion coefficient in polymer solution and molecular weight distribution determined by the diffusion method

The effects of the concentration dependence of the diffusion coefficient of a polymer solution (polystyrene in benzene and cyclohexane) in determining molecular weight distribution by the diffusion method are briefly discussed. The value of the ratio D_m0/D_A0 in a good solvent was found to be close to 1.0 for a polydisperse polymer and less than 1.0 for monodisperse polymers. Molecular weight distribution curves of the polydisperse sample were obtained by the diffusion method in cyclohexane and benzene, respectively. The molecular weight distribution curve obtained for the polymer used in benzene solution looked as if the polymer had a narrow molecular weight distribution. The phenomena cited above were interpreted in the light of the concentration dependence of the diffusion coefficient of polymer solutions.     

管式炉红外碳硫含量仪在轮胎生产用材料硫含量分析中的应用

研究管式炉红外碳硫含量仪在轮胎用原材料硫含量分析中的应用。结果表明：800 ℃试验温度下样品可完全燃烧,但需同步更新测试标准曲线;除不溶性硫黄外样品的称样量取值范围按照标准曲线的中值换算,不溶性硫黄的称样量为中值的40%;测试结果的相对标准偏差小于3%