| The present theories and experimental methods to evaluate the swelling behaviors by gravimetric measurement were experimentally tested for polyvinyl alcohol (PVA) films. It was found that the swelling behaviors and swelling kinetic parameters, such as diffusion exponent n, by gravimetric measurement may be greatly influenced by experimental procedures. In this paper, both the continuous (denoted as scheme A) and the separated (scheme B) experimental procedures of the gravimetric method to evaluate the swelling behaviors were presented and the difference between the two schemes were analyzed. The results suggest that the continuous diffusion of water molecules in films during gravimetric determination may be the key factor affecting the swelling behaviors. The advantages and disadvantages of the two schemes were discussed. It was concluded that an appropriate selection of experimental schemes is effective to extend the applicability range of gravimetric methodology and to increase the accuracy of gravimetric measurement. |
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