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1.
Results of experimental investigations of the effect of drying and atomization parameters on counter-current spray drying
are discussed. Based on 96 experimental tests, the local and global distributions of velocity, temperature, drying air humidity
and moisture content of material dried in the drying tower were determined. Analysis of the results showed that the process
of agglomeration during counter-current spray drying depended mainly on air temperature in the atomization zone. 相似文献
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With an attempt to fabricate large-area OLED lighting panels, we investigate slot-die coating of a small molecule (SM) hole transport layer (HTL). It is observed that SM HTL films formed by spin coating exhibit pinhole-like surface, whereas the films by slot-die coating show micro-sized hillocks due to agglomeration. As the plate temperature of the slot coater is increased, smaller hillocks appear more densely. To tackle it, a small amount of a polymer HTL is added into the SM HTL (Hybrid HTL). By the aid of entangled polymer chains, small molecules are prohibited from migrating and thus agglomerations disappear. The peak-to-peak roughness of the slot-coated hybrid HTL films is measured to be about 11.5 nm, which is slightly higher than that (~7 nm) of the polymer HTL film, but much lower than that (~1071 nm) of the SM HTL film. Similar results are also observed in spin-coated films. It is also addressed that OLED with the hybrid HTL shows higher luminous efficacy, compared to OLED with the SM HTL or the polymer HTL. We have further demonstrated that the dissolution problem occurring between two stacked layers with different solvents during slot-die coating can be suppressed to a great extent using such a combination of materials in hybrid structure. 相似文献
4.
Considering the previous study dealing with thermodynamic and kinetic phenomena (nucleation and crystal growth) during the uranium peroxide precipitation, this work focuses on the agglomeration mechanism. It provides the results obtained from the experiments carried out in a MSMPR reactor operating at steady state. The influence of the operating parameters on the uranium peroxide agglomerates was studied in order to identify the agglomeration kernel. The method is based on the resolution of the population balance equation using the method of moments and the experimental particle size distributions. The results lead to a size-independent kernel directly proportional to the crystal growth rate. Under the stirring conditions studied, the agglomeration appears to be significantly reduced by mixing which results in a kernel inversely proportional to the average shear rate. The agglomeration kinetic law obtained in this study will be used for the process modelling in a further study. 相似文献
5.
In this work the flow induced orientation and the governing mechanism of structural recovery of multi-walled carbon nanotube (MWCNT) filled polypropylene nanocomposites were investigated. A series of linear and nonlinear melt rheological measurements including stress growth and time sweep experiments were performed at different temperatures to study the structural breakdown, nanoparticles orientation, subsequent structural recovery and MWCNT loadings. The results showed that the structural recovery occurred in two stages. The first stage, initial agglomeration, showed a quick recovery which was independent of temperature, can be interpreted in terms of inter-particle van der Waals interactions. This structural recovery stage had major contribution in the storage modulus increment. The second stage of the recovery, secondary agglomeration, was slower and dependent on temperature, can be attributed to rotary diffusion of nanoparticles. This stage had minor contribution to the storage modulus increase. Storage modulus increment in both of these agglomeration was attributed to the increase of nanotube-nanotube contacts. Both of these stages were confirmed by transmission electron micrographs. These result were in a good agreement with those calculated using van der Waals and diffusion concepts. 相似文献
6.
《Particuology》2016
Sol–gel auto-ignition was used to prepare nano-scale magnesium aluminate spinel, using nitrate salts as an oxidizer and glycine–starch mixtures as the fuel. The glycine–starch mixture was varied to understand the effect of fuel mixing ratio on the structural characteristics of the resulting magnesium aluminate. The products were characterized by thermogravimetric-differential thermal analyses, Fourier-transform infrared spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller surface area measurements, and transmission electron microscopy. The phase purity and crystallite size of the powder products depended on the fuel mixing ratio. The presence of starch in the fuel facilitated the preparation of pure nano-particles. To prepare nano-particles of uniform spherical morphology and diameter of <13 nm, the starch content should be optimized to avoid agglomeration. 相似文献
7.
Discrete element method(DEM) is used to studythe factors affecting agglomeration in three-dimensionalcopper particle systems during solid-state sintering.A newparameter is proposed to characterize agglomeration.Theeffects of a series of factors are studied,including particlesize,size distribution,inter-particle tangential viscosity,temperature,initial density and initial distribution of particleson agglomeration.We find that the systems with smallerparticles,broader particle size distribution,smaller viscosity,higher sintering temperature and smaller initial densityhave stronger particle agglomeration and different distributions of particles induce different agglomerations.This studyshould be very useful for understanding the phenomenon ofagglomeration and the micro-structural evolution during sintering and guiding sintering routes to avoid detrimental agglomeration. 相似文献
8.
In order to improve the dispersion of detonation nanodiamonds (ND) in aqueous and non-aqueous media, a series of thermal treatments have been conducted in air ambient to modify ND surface. Small angle X-ray scattering (SAXS) technique and high resolution transmission electron microscopy (HRTEM) were introduced to observe the primary size of ND. Differential thermal analysis (DTA), X-ray diffraction (XRD) methodology, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy were adopted to analyze the structure, bonds at surfaces of the treated ND. Malvern instrument Zetasizer3000HS was used for measuring the surface electric potential and the size distribution of ND. As thermal treatments can cause graphitization and oxidization of functional groups at the surface, ND treated at high temperature is correspondingly more negatively charged in an aqueous medium, and the increased absolute value of zeta potential ensures the electrostatic stability of ND particles. Specially, after being treated at a temperature more than 850 K, ND can be well dispersed in various media. 相似文献
9.
This work addresses the adsorption of benzothiophene (BT), as a model heterocyclic and aromatic sulphur compound present in
road fuels, over agglomerated zeolites with faujasite structure. Several adsorbents based on zeolites with FAU structure have
been prepared with different Si/Al molar ratios and exchange cations and then agglomerated. The influence of the zeolite basicity
has been studied, both in equilibrium and dynamic liquid phase adsorption experiments. Basicity of the adsorbent increased
as the Si/Al molar ratio and the electronegativity of the exchange cation decreased. In equilibrium experiments, the affinity
towards the adsorbent increased as the Si/Al molar ratio decreased, showing the highest affinity for exchanged low silica
X zeolites with medium basicity (A-KLSX-02). Dynamic experiments showed that the less zeolite basicity, the higher fractional
bed utilization and adsorption capacity at breakthrough time. Besides, zeolites with high basicity did not reach the equilibrium
capacity due to the low diffusivity of BT into the micropores. Thermogravimetric analyses of the spent adsorbents showed a
stronger BT adsorption onto the more basic zeolites. As main conclusion, adsorbents with medium basicity could present the
best performance in fuel desulphurization due to their high affinity with sulphur compounds, although diffusion problems should
be taken into account. 相似文献
10.
The surface area of nanosized agglomerates is of great importance as the reactivity and health effects of such particles are
highly dependent on surface area. Changes in surface area through sintering during nanoparticle synthesis processes are also
of interest for precision control of synthesised particles. Unfortunately, information on particle surface area and surface
area dynamics is not readily obtainable through traditional particle mobility sizing techniques. In this study, we have experimentally
determined the mobility diameter of transition regime agglomerates with 3, 4, and 5 primary particles. Agglomerates were produced
by spray drying well-characterised polystyrene latex particles with diameters of 55, 67, 76, and 99 nm. Tandem differential
mobility analysis was used to determine agglomerate mobility diameter by selecting monodisperse agglomerates with the same
number of primary particles in the first DMA, and subsequently completely sintering the agglomerates in a furnace aerosol
reactor. The size distribution of the completely sintered particles was measured by an SMPS system, which allowed for the
determination of the number of primary particles in the agglomerates. A simple power law regression was used to express mobility
diameter as a function of primary particle size and the number of primary particles, and had an excellent correlation (R2 = 0.9971) with the experimental data. A scaling exponent was determined from the experimental data to relate measured mobility
diameter to surface area for agglomerates. Using this relationship, the sintering characteristics of agglomerates were also
examined for varying furnace temperatures and residence times. The sintering data agreed well with the geometric sintering
model (GSM) model proposed by Cho & Biswas (2006a) as well as with the model proposed Koch & Friedlander (1990) for sintering by viscous flow. 相似文献