Development of porous zirconia spheres by polymerization-induced colloid aggregation — effect of polymerization rate
- 176 Downloads
Polymerization-induced colloid aggregation is used to synthesize spheres of narrow size distribution which are porous aggregates of ZrO2 colloids. Variation of the reaction pH has been investigated to determine the optimum rate of polymerization of the urea-formaldehyde resin. At the optimum rate, a colloid packing structure is formed where a balance of high porosity and high strength of the aggregates is achieved. This optimum coincides with the maximum yield of the ∼5 μm sintered (polymer-free) particles. Particles synthesized at pH values below the optimum are mechanically weak; some are hollow spheres. Variation of the pore structure, and thus colloid packing structure, is elucidated by nitrogen adsorption and apparent density measurements. Differences on either side of the optimum pH are related to the efficiency of polymer-bridge formation between colloids.
KeywordsPorosity Zirconia Pore Structure Maximum Yield Density Measurement
Unable to display preview. Download preview PDF.
- 3.P. W. Carr, E. F. Funkenbusch, M. P. Rigney, P. L. Coleman, D. A. Hanggi and W. A. Schafer, US Pat. 5015 373 (1991).Google Scholar
- 4.M. J. Wax and R. K. Grasselli, EP Pat. 0490226 A1 (1991).Google Scholar
- 5.R. K. Iler and H. J. McQueston, US Pat. 4010242 (1977).Google Scholar
- 8.G. J. Fleer, and J. M. H. M. Scheutjens, Croat. Chem. Acta 60 (1987) 477.Google Scholar
- 18.R. W. Stout and H. J. Leibu, EP Pat. Appl. 0341 556 (1989).Google Scholar
- 19.J. I. De Jong and J. De Jonge, Rec. Trav. Chim. 53 (1953) 139.Google Scholar
- 20.H. G. B. De Jong, in “Colloid Science”, Vol. II, edited by H. R. Kruyt (Elsevier, New York, 1949) p. 253.Google Scholar