Electrokinetic characterisation of cationic amylopectin starch; screening by salt and screening by nanosized silica particles

The screening of cationic amylopectin starch with salt has been investigated using the technique of electrokinetic sonic amplitude. The dynamic mobility was found to decrease as the electrolyte concentration increases. The experimental data were satisfactorily explained by applying a porous sphere model. The radius of the porous sphere could be used to evaluate the contraction of the amylopectin molecule as the electrolyte concentration increases. The screening of cationic amylopectin starch with nanosized silica particles was also followed using the technique of phase analysis light scattering. The formation of large macroscopic flocs could be explained in terms of available cationic and anionic sites of the initially formed polyelectrolyte complexes between one amylopectin molecule and a number of small silica particles. (C) 1997 Elsevier Science Ltd. All rights reserved.