Particle size distribution significance

In this case, ion exchange of the latex may alter the particle-size distribution significantly and thus lead to substantial errors in its experimental determination. 

However, in the case of mini- and microemulsions, processing methods reduce the size of the monomer droplets close to the size of the micelle, leading to significant particle nucleation in the monomer droplets (17). Intense agitation, cosurfactant, and dilution are used to reduce monomer droplet size. Additives like cetyl alcohol are used to retard the diffusion of monomer from the droplets to the micelles, in order to further promote monomer droplet nucleation (18). The benefits of miniemulsions include faster reaction rates (19), improved shear stabiHty, and the control of particle size distributions to produce high soHds latices (20). 

Glassification. Classification (2,12,26,28) or elutriation processes separate particles by the differences in how they settle in a Hquid or moving gas stream. Classification can be used to eliminate fine or coarse particles, or to produce a narrow particle size distribution powder. Classification by sedimentation iavolves particle settling in a Hquid for a predetermined time to achieve the desired particle size and size distribution or cut. Below - 10 fim, where interparticle forces can be significant, gravitational-induced separation becomes inefficient, and cyclone and centrifugation techniques must be used. Classification also separates particles by density and shape. Raw material separation by differential sedimentation is commonly used in mineral processiag. 

Tailoring of the particle size of the crystals from industrial crystallizers is of significant importance for both product quality and downstream processing performance. The scientific design and operation of industrial crystallizers depends on a combination of thermodynamics - which determines whether crystals will form, particle formation kinetics - which determines how fast particle size distributions develop, and residence time distribution, which determines the capacity of the equipment used. Each of these aspects has been presented in Chapters 2, 3, 5 and 6. This chapter will show how they can be combined for application to the design and performance prediction of both batch and continuous crystallization. 

The significance of this novel attempt lies in the inclusion of both the additional particle co-ordinate and in a mechanism of particle disruption by primary particle attrition in the population balance. This formulation permits prediction of secondary particle characteristics, e.g. specific surface area expressed as surface area per unit volume or mass of crystal solid (i.e. m /m or m /kg). It can also account for the formation of bimodal particle size distributions, as are observed in many precipitation processes, for which special forms of size-dependent aggregation kernels have been proposed previously. 

The above-described laws of filler distribution in heterogeneous mixtures of polymers are true when the particle size is significantly less than the size of the polymer zones in such mixtures (1 to 10 p). So, powders of graphite and molibdenum (Ss = = 2 m2/g) are distributed equally uniformly in all the studied mixtures of polymers irrespective of the mixing conditions for in this case the particle size is comparable with the size of the polymer zones. 

For L=NH3 (1) and L=Pr2NH (3), the isotherms are of type II as expected for non-porous materials [27]. Sample 2 shows a significant uptake at 0.6

narrow particle-size distribution which results in a more regular packing with interparticle pores of size similar to that of the particles [27]. The latter shows that the ligand-assisted synthesis does not only allow one to affect the total surface area and particle size, but also the size distribution which is an important tool for tailoring the particle properties. 

ALL METHODS FOR PRESENTING DATA FROM THE MEASUREMENT OF PARTICLE SIZE DISTRIBUTIONS, WHETHER INSTRUMENTAL, SEIVING, SEDIMENTATION, OR PHOTOMETRIC METHODS, MEASURE FRACTIONS OF THE TOTAL PARTICLE DISTRIBUTION. IF THE METHOD IS SENSITIVE, THE FRACTION-SEGMENTS CAN BE SMALL, AND THE MEASURED PARTICLE DISTRIBUTION WILL BE CLOSE TO THE ACTUAL ONE. IF THE MEASUREMENT IS LESS SENSITIVE, THERE MAY BE SIGNIFICANT DEVIATIONS FROM THE CORRECT PSD. 

Ukraine. It was observed that the particle size distribution of products does not vary significantly during cycling. 

Particle Size Distribution. The particle size distribution is a significant factor with respect to attrition. Coarser particles tend more to fragmentation while smaller particles have a stronger inclination to abrasion because of their large specific surface. Since the particle degradation is composed of fragmentation as well as abrasion, both the amount and the... 

This synergism of Group B-C mixtures testifies to the significance of particle size selection and particle size distribution design, in order to tailor a solid particulate material to certain desired fluidizing characteristics. 

Theoretical calculations of unattached fractions of radon or thoron progeny involve four important parameters, namely, 1) the count median diameter of the aerosol, 2) the geometric standard deviation of the particle size distribution, 3) the aerosol concentration, and 4) the age of the air. All of these parameters have a significant effect on the theoretical calculation of the unattached fraction and should be reported with theoretical or experimental values of the unattached fraction. 

Evaluation of the morphology of a pharmaceutical solid is of extreme importance, since this property exerts a significant influence over the bulk powder properties of the material. In addition to providing insights into the micromeritic properties of the solid, microscopy can also be used to develop preliminary estimations of the particle-size distribution. A determination can be easily made regarding the relative crystallinity of the material, and it is often possible to deduce crystallographic information as well. Unknown particulates can often be identified solely on the basis of their microscopic characteristics, although it is useful to obtain confirmatory support for these conclusions with the aid of microscopically assisted techniques. 

In spite of the fact that all of these values are quoted freely in the literature, it is only the median that seems to be of any physical significance, considering the typically unsymmetric particle size distributions of organic pigments. 

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