Persulfate-amine initiation systems for gelcasting of ceramic foams

The in situ polymerization of organic monomers to consolidate ceramic suspensions in the form of gelled bodies with very complex shapes has recently been employed for the manufacture of both dense and porous ceramics. The control of the polymerization rate is very important, particularly for the porous ceramics where there is the need for fast consolidation to retain the foamed suspension without damage to the pore structure or loss of pore volume. In the current work, ammonium acrylate and methylenebisacrylamide were used to promote gelation of foamed alumina suspensions. A variety of amine catalysts were tested in combination with ammonium persulfate as initiating systems for polymerization. Analysis of the exothermic profiles registered during polymerization revealed that the polymerization onset and rates are markedly influenced by the concentration and type of initiating species, with tertiary diamines being the most efficient accelerators.