Isothermal kinetic studies using a thermomechanical analyzer I. Rates of polymer swelling and dissolution

The use of a commercially available thermomechanical analyzer (TMA) operated in its isothermal mode is illustrated for studies of polymer‐swelling and dissolution in liquids. Results for a variety of polymer‐swelling agent systems demonstrate that information usually requiring more sophisticated experimental techniques can be readily obtained with the TMA. In particular rates of swelling and penetrant diffusion coefficients can be determined for selected systems. Dissolution measurements, exemplified here for polystyrene in three different solvents, can be utilized to obtain steady state rates of solvent penetration and rough estimates of the interdiffusion coefficient for a system. The experimental limitations involved in both types of measurement are discussed.