The Effect of Plasticizers on the Properties of Polyvinyl Alcohol Films

Abstract

The effect of water-soluble plasticizers viz propylene glycol (PG), glycerol and polyethylene glycol 600 (PEG) on the morphology and water resistance of polyvinyl alcohol (PVA) films was investigated. Polyvinyl alcohol films were cast from aqueous solutions, and their morphology studied using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Water resistance was characterized by the extent of film dissolution and the water uptake capacity of remnant films after immersion of the films in distilled water for 3 days at 37° C. DSC thermograms showed that crystallite formation in the PVA films was affected to different extent by addition of the three plasticizers. The plasticizers not only reduced the degree of crystallinity in the films, but also lowered the crystalline melting temperatures probably by introducing defects into the crystal lattice. This factor, coupled with leaching of the water-soluble plasticizers from the films when immersed in distilled water, lowered the water resistance of the plasticized PVA films. The influence of plasticizers on the properties of PVA films was further related to the degree of compatibility between the plasticizers and PVA.