Effect of plasticizer on free volume and permeability in cellulose acetate pseudolatex membranes studied by positron annihilation and tracer diffusion methods
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Plasticizers influence the permeability and mechanical properties of the polymer membranes that are used in controlled drug release systems. Positron annihilation spectroscopy (PAS) and tritium tracer diffusion methods were used to study the changes in free volume and permeability of cellulose acetate psuedolatax films as a function of diacetin concentration. O-Ps lifetime component was used to estimate the free volume parameters. The hole size and the total free volume fraction increased with %diacetin. The hole concentration increased with %diacetin reaching to a maximum at 130%, and then decreased. The permeability determined by tracer diffusion experiments with tritiated water showed a gradual increase up to 150% and then showed a drastic increase. A two step diffusion model is proposed to explain the variations in the diffusion and the free volume results.
author list (cited authors)
Naidu, S. V., Sastry, S. V., Maxie, C. S., & Khan, M. A.