Control of particle size distribution

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). 

Stricter control of particle size distribution improves powder handling (qv) and transport through the system, and appHcation efficiency. It also reduces blinding of the final filter (69). Additives have been developed which improve the triboelectric charging characteristics (70). 

Control of Particle Size Distribution Through Emulsifier Metering Based on Rate of Conversion... 

Collin A. 1997. Online control of particle size distribution. Spectra Anal. 26(196) 31-33. 

Practical applications do not always require tight control of particle size distributions, but the necessity for avoiding generation of new particles at any stage after the first polymerization process may necessitate this precaution. Analysis of the particle size distribution alier successive polymerizations is a simple expedient to ensure that later stages have produced polymer that is attached to the previously existing particles. 

The realisation of very high solids contents in commercial latexes through inventive control of particle size distribution has created a need for both theoretical and experimental research into the rheological behaviour of polymer colloids at high particle volume fractions. 

Crowley, T.J. Meadows, E.S. Kostoulas, E. Doyle, F.J. Control of particle size distribution described by a population balance model of semibatch emulsion polymerization. J. Process. Control 2000, 10 (5), 419-132. 

Nucleation and Growth, and Control of Particle Size Distribution... 

The major distinction between the model of La Mer and that developed for uniform latex particles lies in the incorporation of colloidal stability of small particles. The La Mer model assumes that each nucleus is colloidally stable and survives at the end of the reaction at the center of a particle. The aggregation models argue that stabilizing primary small particles is difficult, but aggregation does not necessarily result in a broad particle-size distribution. When schemes for control of particle-size distribution are developed, the result of accepting the notion that colloidal stability can play an important role is that attention is focused away from the length of the nucleation period and towards the colloidal properties of the growing particles. 

Control of particle size distribution Manufacturing time... 

Antiblocking is the prevention of the adhesion of two plastic films in contact with one another. This effect can be achieved by incorporating fine silica particles in the surface of the film. The relatively low refractive index of silica makes the particles less easy to see. Good control of particle size distribution is important. 

The formulation of agrochemicals as aqueous suspensions (suspension concentrates) has attracted considerable attention in recent years. This is due to the advantages produced by these systems, e.g. control of particle size distribution, ease of application (flowable systems that can be easily dispersed in the spray tank) and the possibility of incorporation of high surfactant concentrations which in many case are essential for biological control. 

The strategy of top down is considered traditional for powders fabrication. Nanoparticles are the product of milling of large pieces of any material. The grinding process may also be accompanied by chemical and phase transformations. Theoretically, any substance can be crushed or converted to a vapor state and then condensed. However the problems of impurities, control of particle size distribution and the properties of agglomerates still remain open. 

An isothermal mode of process does not allow easy control of particle size distribution and agglomerate size and strength. Alternatively, the heating rate during calcination is an effective control parameter for the particle size distribution during non-isothermal reaction with controlled rate [281, 282, 291]. Thermal decomposition of barium titanyl oxalate BaTi0(C204)2 was performed in a wide... 

Gordon, D. L. and Weidner, K. R. (1981) Control of particle size distribution through emulsifier metering based on rate of conversion, Emulsion Polymers and Emulsion Polymerization (eds D. R. Bassett and A. E. Hamielec), ACS, Washington, pp. 515-32. 

Mahoney, A. W. Investigation of Population Balance Models towards Control of Particle Size Distribution, PhD. Thesis, Purdue University, West Lafayette, In, 2000. 

Additionally, improvements in catalyst preparation methods have resulted in better control of particle-size distribution and the chemical composition of catalysts. CO tolerance was enhanced by Pt-based catalysts prepared using high energy ball milling [119], sulfiding (synthesized using Na2S203) [120], and combustion synthesis [121]. 

F. J. Doyle, C. A. Harrison, T. J. Crowley, Hybrid model based approach to batch-to-batch control of particle size distribution in emulsion polymerization . Computers Chem. Eng., 2003, 27, 1153. 

Shi D, El-Farra NH, Li M, Mhaskar P, Christofides PD. Predictive control of particle size distribution in particulate processes. Chem Eng Sci 2006 61 268-281. 

Nucleation and growth and control of particle size distribution... 

---