Influence of Particle Properties

Both convective and capillary assemblies have been shown to be compatible with macromolecule-sized nanoparticles with diameters 10 nm. Unfortunately such small particles do not form well-ordered structures as compared to larger ones, t)q ically above 50 nm. These results bring up important questions for further studies, in particular how solvent fluctuations, substrate interactions, and thermod5mamic states affect drying patterns in a confined geometry. 

The compatibility of the assembly mechanism with particles over a few micrometers in size has to be investigated carefully. Indeed, as it has been described all along in this chapter, particle mobility is a key factor in both assembly mechanisms. Capillary and convective 

These particles tend to sediment within a few minutes and are no longer sensitive to solvent fluxes created by evaporation. Nevertheless, the capillary forces exerted by the meniscus are sufficient to drag particles deposited on flat areas. This mechanism induces an accumulation of particles close to the contact line and finally leads to a selective immobilization of particles in the recessed areas of the template. Here also, the accumulation process is required to induce particle deposition. 

The possibility of assembling anisotropic particles is an interesting feature and has been mainly investigated in capillary assembly. Complex particles such as tetrahedrally shaped CdTe nanotetrapods were successfully assembled. The assembly of nanorods and nanowires was also reported.  

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No consideration is given to the influence of particle properties and/or duct diameter... 

Fig. 41. Influence of particle properties on axial dispersion of the emulsion phase Uq = 20 cm/sec with variable bed diameter Dj keys are given in Fig. 40. Data by May (Ua = 25 cm/sec) and those by Stemerding (l/

DPMs can also be used to understand the influence of particle properties on fluidization behavior. It has been demonstrated that ideal particles with restitution coefficient of unity and zero coefficient of friction, lead to entirely different fluidization behavior than that observed with non-ideal particles. Simulation results of gas-solid flow in a riser reactor reported by Hoomans (2000) for ideal and nonideal particles are shown in Fig. 12.8. The well-known core-annulus flow structure can be observed only in the simulation with non-ideal particles. These comments are also applicable to simulations of bubbling beds. With ideal collision parameters, bubbling was not observed, contrary to the experimental evidence. Simulations with soft-sphere models with ideal particles also indicate that no bubbling is observed for fluidization of ideal particles (Hoomans, 2000). Apart from the particle characteristics, particle size distribution may also affect simulation results. For example, results of bubble formation simulations of Hoomans (2000) indicate that accounting... 

R. Wakeman, The Influence of Particle Properties on Filtration, Separation and Purification Technology, 58 (2007), 234-241. 

With the following example, we illustrate how in a sequence of activities the students intuitive notions about the influence of particle size and the sintering temperature of the clay on the properties of ceramic materials have productively been used (Klaassen Lijnse, 1996 Mortimer Scott, 2003 Duit Treagust, 2003 ... 

Litka, T., and Glicksman, L. R., The Influence of Particle Mechanical Properties on Bubble Characteristics and Solid Mixing in Fluidized Beds, Powder Technol., 42 231 (1985)... 

Influence of Particle Size and Interaction with the Support on Redox and Catalytic Properties of Metals, Metal Oxides, and Metal Complexes... 

M. Che, and C. O. Bennett, The influence of particle size on the catalytic properties of supported... 

Chem. Geol. 157 275-284 Meisel.W. (1989) Corrosion processes and their inhibition as studied by Mdssbauer conversion and other electron spectroscopies. Hy-perfine Interactions 45 73-90 Meisen, U. Kathrein, H. (2000) The influence of particle size, shape and particle size distribution on properties of magnetites for the production of toners. J. Imag. Sci. Techn. 44 508-513... 

The following experiment should demonstrate the influence of particle size and mini-mai fiim-formation temperature (which is connected with the glass transition temperature and therefore with the chemical structure of the polymers) on the properties of fiims, prepared from aqueous dispersions. 

Podczeck F. The influence of particle size distribution and surface roughness of carrier particles on the in vitro properties of dry powder inhalations. Aerosol Sci Technol 1999 31 (4) 301 321. 

As we shall see later when we consider the influence of particle size on adsorption, this dispute may turn out to be more of academic than of practical importance. Adsorption is less sensitive than are bulk properties to variations in particle size. 

The foregoing sections have been concerned with the effect of particle size on the structure and properties of small metal particles. Several general comments can be made concerning the influence of particle size on catalytic properties. 

The effects of liquid velocity (at least at low velocities), direction of flow and liquid properties are only minor for Newtonian fluids. Correlations on gas-liquid columns are given by Joshi [63], Field and Davidson [64] measured the dispersion in a large industrial column (de - 3.2 m, H — 19 m) and found agreement with the correlations of Dcckwer et al. [65] and Joshi [63] (Tabic 3). The influence of particles can be expected to be small, at least for low concentrations and small particles. This is confirmed by the early experiments of Kato et al. [15, 69], For particle sizes ranging from 63... 

They found that optimal conditions of the position of the stirrer exist in the range of 0.25 < HJd < 0.75 for both turbine and propeller stirrers. Their work suggests that beyond a Reynolds number of 20,000, the power number becomes constant. An increase in solid content increases the power consumption, while an increase in gas velocity reduces the power consumption. Kurten and Zehner (1979) examined the effect of gas velocity on the power consumption for suspension of solids and found that because of simultaneous aeration, a higher power input is required for suspension in the presence of gas. This is mainly due to the reduced liquid circulation velocity in the presence of gas bubbles. Most recently, Albal et al. (1983) evaluated the effect of liquid properties on power consumption for both two- and three-phase systems. They found that power consumption per unit volume increases with solid concentration. The influence of particle size on power consumption increases with the solids concentration. For an unconventional arrangement of a stirrer, they also found different Ne-Re curves for glycerine and CMC solutions. 

Work undergone in this area has looked at tensile and impact properties of a PVC composite filled with hollow glass beads, of three different sizes, and different volume fractions (96). The influence of particle shape and silane coupling agents, for surface treatment of glass beads, on mechanical properties has also been investigated (116, 366). 

Two test rigs have been built for investigation of the combustion processes in a bed of solid fuels and particularly the influence of primary airflow and of particle properties (size, density and thermal conductivity) on the rate and temperature of the ignition front. Also the gas composition downstream of the bed has been investigated. The following conclusions can be drawn from the results ... 

Podczeck F, Newton JM, James MB. The influence of physical properties of materials in contact on the adhesion strength of particles of salmeterol base and salmeterol salts to various substrate materials. J Adhesion Sci Technol 1996, 10, 257-268. 

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