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Abstract
Hydroxypropyl methylcellulose (HPMC) is a cellulosic polymer widely employed in tablets formulation. In contact with biological fluids, it undergoes a glassy–rubbery transition and drug release is strongly influenced by swelling. We study the kinetic parameters of a classical phenomenological model (Astarita and Sarti), which describes the velocity of a glassy–rubbery interface as a function of the local solvent concentration. One-dimensional mass transport equations with moving boundaries are numerically solved by finite elements method in order to fit Astarita–Sarti parameters k and n on experimental swelling fronts and concentration profiles taken from literature for HPMC K4M, HPMC K15M, and HPMC K100M.