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Effect of carboxyl group in monosaccharide ring on viscosity of nanometric alumina suspension
|Paweł Falkowski 1, Mikolaj Szafran 1, Andrzej Temeriusz 2
1. Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, Warszawa 00-664, Poland
In the last few years many different methods of synthesis and characterization of nanopowders were developed. Unfortunately, there are still no good and efficient methods of moldings of nanopowders. One of the major problems is high tendency of nanopowders to agglomeration. This effect causes that it is difficult to obtain materials with nanostructure after sintering. Therefore the molding methods which allow reducing the agglomeration and giving homogeneity in green bodies and after sintering are searched for.
It is possible to reduce agglomeration of nanopowders through introduction of dispersing agents into ceramic suspension in slip cast method. Previous researches showed that addition of monosaccharides is very effective in reducing the viscosity of suspensions of nanometric alumina particles. The monosaccharides as processing additives have a number of advantages. They are nontoxic, soluble in water, readily available and inexpensive.
The viscosity of suspension with various monosaccharides differ widely Because the monosaccharides differ from each other only in location of substituent groups in space the observing diversity of properties is the result of differences in chemical structures of hexose.
The deflocculating properties of monosaccharides can be increase by substitution of carboxyl group into monosaccharide ring. It may be due to the deprotonation/protonation processes that occur in alumina suspensions with addition of acid derivative. It is also possible that higher amount of H+ ions introduced with acid can change a double electric layer. The substituted carboxyl groups may change the structure of sugar molecule and influence on adsorption of monosaccharides onto nanopowder alumina particles.
This work was financially supported by Ministry of Science and Higher Education: Grant No. N205 009 31 / 0353
Presentation: Poster at E-MRS Fall Meeting 2008, Symposium I, by Paweł Falkowski
See On-line Journal of E-MRS Fall Meeting 2008
Submitted: 2008-05-19 14:01 Revised: 2009-06-07 00:48