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A. Bartkowiak, W. Brylak

Hydrogel microcapsules containing natural or chemically modified

oligochitosan - mechanical properties and porosity

Polimery 2006, No 7-8, 547



Summary

Attempt has been made to determine the effect of the concentration of the solutions of anionic polysaccharides and cationic oligochitosans (modified or not) on some properties of the systems obtained. They were either binary microspheres: sodium alginate/Ca+2 cation or ternary ones: sodium alginate/Ca+2 cation/oligochitosan (or its quaternary ammonium derivatives) (Fig. 1, Table 1). Selection of solution concentration let control the porosity (determined on the basis of molar mass cut-off by gel permeation chromatography - Fig. 2). The investigations confirmed the possibility of oligochitosan applications to the formation of mechanically stable microcapsules. The use of modified oligomers let control both the mechanical strength of outer membrane of microcapsule and porosity. The prepared hydrogel systems show high stability of compression strength what was find on the basis of fatigue tests (Table 3). Non-destructive relaxation tests results allowed finding the preliminary correlation between compression strength and porosity of microcapsules and coefficients in the equation describing the relaxation curves [equation (3), Table 2, Fig. 4-6].


Key words: hydrogel microspheres, microcapsules, sodium alginate, oligochitosan, quaternary ammonium salts, porosity, compression strength, fatigue tests, relaxation


e-mail: bartkowiak@tz.ar.szczecin.pl


A. Bartkowiak, W. Brylak

Hydrogel microcapsules containing natural or chemically modified oligochitosan - mechanical properties and porosity