Effects of Plasticizers on Water Permeation and Mechanical Properties of Cellulose Acetate: Antiplasticization in Slightly Plasticized Polymer Film

Abstract

The effects of plasticizers, triacetin and three different molecular weights of polyethylene glycol, on the water permeation and mechanical properties of cellulose acetate were investigated. At 37°C, the water permeability of cellulose acetate was found to decrease with increasing plasticizer to a minimum and then to increase with higher concentrations of plasticizer. Low plasticizer concentrations caused a decrease in water permeability by antiplasticization. Antiplasticization arose from an interaction between the polymer and the plasticizer molecules and decreases the molecular mobility of the polymer. This effect was confirmed by mechanical measurements of polymer free films at the same experimental temperature. However, when the temperature was raised above the glass transition temperature, T_g, of the polymer films, the polymer films contain enough energy to overcome the interaction between the polymer and plasticizer molecules, and the antiplasticization effect disappeared.