A modified emulsion polymerisation synthesis route for preparing highly dispersed cationic polystyrene (PS) nanoparticles is reported. The combined use of 2,2′-azobis[2-(2-imidazolin- 2-yl)propane] di-hydrochloride (VA-044) as the initiator and acetone/water as the solvent medium afforded successful synthesis of cationic PS particles as small as 31 nm in diameter. A formation mechanism for the preparation of PS nanoparticles was proposed, whereby the occurrence of rapid acetone diffusion caused spontaneous rupture of emulsion droplets into smaller droplets. Additionally, acetone helped to reduce the surface tension and increase the solubility of styrene, thus inhibiting aggregation and coagulation among the particles. In contrast, VA-044 initiator could effectively regulate the stability of the PS nanoparticles including both the surface charge and size. Other reaction parameters i.e. VA-044 concentration and reaction time were examined to establish the optimum polymerisation conditions.
An analysis of the effect of feed foaming on the efficiency of sunflower oil encapsulation on selected product properties is presented in the paper. Experiments were carried out in a pilot-plant concurrent spray dryer using the gas-admixing technique. The analysis of the product properties showed that the application of foaming makes it possible to control final product properties, e.g. apparent density, bulk density, distribution of particle diameters, etc. at a high efficiency of sunflower oil encapsulation.
Concentration and dispersion distributions of mineral suspension and crude-oil particles in waters of the Kongsfiord (Spitsbergen) were examined in 1997. Most suspension occurs at glacier margins and decreases towards a fiord outlet.
The effect of emulsifier volume on emulsion system stability of plant origin being the basis of diet supplements for animals in winter season was analyzed. For this purpose, measurements of the backscattered light intensity as the function of the measuring cell height were conducted with a Turbiscan LAB optical analyzer. System stability was analyzed on the basis of Turbiscan Stability Index values. A Helos laser analyzer and a Nikon Eclipse E400 POL optical microscope were used to investigate drop size distribution and analyze microscopic pictures. It was shown that emulsion with 10% (w/w) of the emulsifier was the most stable one.
The blasting technique is currently the basic excavation method in Polish underground copper mines. Applied explosives are usually described by parameters determined on the basis of specific standards, in which the manner and conditions of the tests performance were defined. One of the factors that is commonly used to assess the thermodynamic parameters of the explosives is the velocity of detonation. The measurements of the detonation velocity are carried out according to European Standard EN 13631-14:2003 based on a point-to-point method, which determines the average velocity of detonation over a specified distance. The disadvantage of this method is the lack of information on the detonation process along the explosive sample. The other method which provides detailed data on the propagation of the detonation wave within an explosive charge is a continuous method. It allows to analyse the VOD traces over the entire length of the charge. The examination certificates of a given explosive usually presents the average detonation velocities, but not the characteristics of their variations depending on the density or blasthole diameter. Therefore, the average VOD value is not sufficient to assess the efficiency of explosives. Analysis of the abovementioned problem shows, that the local conditions in which explosives are used differ significantly from those in which standard tests are performed. Thus, the actual detonation velocity may be different from that specified by the manufacturer. This article presents the results of VOD measurements of a bulk emulsion explosive depending on the diameter of the blastholes carried out in a selected mining panel of the Rudna copper mine, Poland. The aim of the study was to determine the optimal diameter of the blastholes in terms of detonation velocity. The research consisted of diameters which are currently used in the considered mine.
A mathematical model, created for description of the mechanism of interaction between basic parameters of high pressure dispersion of emulsions, is presented in this paper. The model is applied for the analysis of the influence of physical properties of emulsions, quantitative content of dispersed emulsion phase and parameters of emulsification, pressure and temperature, on the characteristic dimension of particles of the dispersed phase. The model makes it possible to determine appropriate process parameters, especially the pressure necessary to obtain the required dispersion of the emulsion and to define construction and exploitation parameters of high-pressure emulsification valve.
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