Changes in longevity, sub-microporosity, and density of polymer films obtained from solutions in different solvents were studied, using samples of cellulose triacetate, poly(vinyl chloride) and poly(methyl methacrylate). The characteristics were determined by the quality of the solvent in relation to the polymers studied. A correlation was established between the size of the micropores, density, and life of the films. -- AATA