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Porous Ceramics: Application for Polyethylene Microspheres
Background:
Usually porous ceramics are made from aluminum oxide, silicon carbide or Zirconia. Most porous ceramics have a natural ability to fill pores by capillary action. This makes porous ceramics water accepting, thus they also are referred to as hydrophilic material. This means the pores and channels of a ceramic have a highly charged pore surface that attracts and bonds the polar molecules of water and other polar fluids. The net effect is called “wicking” — the ability to pull fluids into the material and transport that fluid by capillary forces. The pore size directly affects the ceramic’s air entry or bubbling pressure and hydraulic conductivity. The effective pore size is determined by the minimum orifice within a channel or pore.1
Some porous ceramic have 40-50% open porosity with a tortuous pore structure and is available in pore sizes ranging from 0.25 to 90 microns. Monolithic, single grade, aluminum oxide porous ceramic is available in 6, 15, 30, 50, 60 and 90 micron pore sizes. In addition, some ceramic membranes can use a medium pore substrate with a thin coating of fine porous ceramic membrane in 0.25, 1, 3 and 6 micron pore sizes.2 Continue reading “Porous Ceramics: Application for Polyethylene Microspheres” »
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Dual nanocomposite multihollow polymer microspheres prepared by suspension polymerization based on a multiple pickering emulsion
Excerpts from an interesting approach to creating hollow polymer microspheres from a pickering emulsion.
Abstract:
A solid-stabilized multiple w/o/w or o/w/o emulsion was prepared in a two-step process. Various nanocomposite polymer microspheres with multihollow armored closed pores were fabricated easily by suspension polymerization of the multiple Pickering stabilized emulsions.
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Chitosan microspheres prepared by spray drying
Spray drying has been used in the production of fine powders from emulsions for many years, but it is not a process in which most people associate the production of microspheres. This journal article shows how the authors were able to produce highly spherical microspheres in the 2-10um range by controlling the levels of Chitosan and crosslinking agents used.
The key items I found of interest in this article were:The quality of the microspheres that were produced, as seen the the attached SEM micrograph.
How the process variables did not affect the zeta potential of the microspheres produced (Table 4 below), and how the size can be varied by varying the concentrations of Chitosan or the Molecular weight (MW). Continue reading “Chitosan microspheres prepared by spray drying” »
