Characterization of ethylcellulose free films by positron annihilation spectroscopy and mechanical testing

The distribution of the plasticizer triethyl citrate between the chains of the polymer ethylcellulose was determined in order to explain the mechanical properties. A knowledge of these properties is indispensable for preformulation studies. As preformulation, the relationship between the mechanical properties and the distribution of the plasticizer was studied. The distribution was investigated with positron annihilation lifetime spectroscopy, and the mechanical properties with breaking hardness tests. Two kinds of ethylcellulose were used. The best film-former with plasticizer was chosen with the optimal concentration. Selection of the optimum type and concentration of the plasticizer is essential in the formulation of pellets and coated dosage forms.