Persulfate-amine initiation systems for gelcasting of ceramic foams

The in situ polymerization of organic monomers to consolidate ceramic suspe nsions in the form of gelled bodies with very complex shapes has recently b een employed for the manufacture of both dense and porous ceramics. The con trol of the polymerization rate is very important, particularly for the por ous ceramics where there is the need for fast consolidation to retain the f oamed suspension without damage to the pore structure or loss of pore volum e. In the current work, ammonium acrylate and methylenebisacrylamide were u sed to promote gelation of foamed alumina suspensions. A variety of amine c atalysts 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, wi th tertiary diamines being the most efficient accelerators.