Sudipto Roy, Priyadarshi Majumdar
The present study is a simple experiment with the most commonly used and abundantly available spherical hydrogel crystal beads. Immersing the beads in distilled water, both mass and volume were measured at regular time intervals. The experimental results thus obtained have been explained on the basis of analytical and numerical approach. A theoretical model has been developed based on the consideration of water absorption through vacant polymer sites in a highly porous hydrogel. Considerations of cylindrical and spherical pores in this model predicted almost the same swelling behaviour. Expressions relating to the mass and the volume of hydro-gels with time have been formulated and it has been shown that the theoretical plots almost fit the experimental data and using the experimental result several swelling parameters (e.g. the characteristic time, pore sizes etc.) have been evaluated. In this regard the maximum number of water molecules which may be attached to the active polymer sites in a single crystal bead has been calculated. The results found during this experiment seem to be similar to those found in some earlier similar type of experiments hence validating the assumptions made in the analytical model used by us.
