Effects of Propylene Glycol on the Physical Properties of Poly(Vinyl Alcohol) Solutions and Films

Abstract

The rheological properties of poly(vinyl alcohol) (PVA) solutions in dimethyl sulfoxide (DMSO) and the physical properties of PVA films were investigated in terms of propylene glycol (PG) content in PVA. As the PG content was diminished, the solutions showed higher viscosity and more noticeable Bingham behavior. The yield stress of the solutions was increased with increasing temperature and concentration. However, increase in PG content reduced it. 6 wt% PVA solutions containing PG more than 30 wt% gave rise to an abrupt reduction of dynamic viscosity and storage modulus over the frequency range 0.08 and 0.2 rad/s. Further they showed a sudden decrease of relaxation time. On the other hand, 12 wt% solutions did not exhibit this discontinuous change of rheological parameters with PG content. As the PG content was increased, the tensile strength of PVA films were decreased but elongation at break was increased. Thus, incorporating PG in PVA toughened the resultant films up to a critical PG content.