Abstract
Swelling behaviour of alginic acid gel beads with different chemical
composition, molecular weight and size was studied in acetate buffer
at pH 4. A correlation was observed between the swelling behaviour
in this buffer and the equilibrium properties of alginic acid gels.
High contents of long L-guluronic acid blocks (G-blocks), known to
give a high acid gel strength, reduced the rate of swelling and also
the amount of solubilized alginate molecules leaching out of the
gel beads. Compared to the original alginate, the leaching molecules
had a lower average molecular weight, higher content of mannuronic
acid residues and a reduced average length of G-blocks. Swelling
capacity, rate of swelling and solubility of alginic acid seemed
to depend on a balance between the tendency of homopolymeric blocks
to form intermolecular junction zones, and the tendency of alginate
to reduce the chemical potential of water. As expected, swelling
rate increased with increasing temperature and decreasing bead size.
Copyright (C) 1996 Elsevier Science Limited.
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