Submitted to: Journal of Applied Polymer Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/19/2012
Publication Date: 5/14/2012
Citation: Wyatt, V.T. 2012. Effects of swelling on the viscoelastic properties of polyester films made from glycerol and glutaric acid. Journal of Applied Polymer Science. 126:1784-1793. Interpretive Summary: Developing new outlets for glycerol would have a significant impact on the economics of biodiesel production if value-added products made from glycerol can be identified. Glycerol is the major co-product produced from the process used to make biodiesel. Before the introduction of biodiesel-derived glycerol, the glycerol market was already saturated with uses in the food industry and in many pharmaceutical, chemical, and personal care applications. Therefore, increased production of biodiesel created a need to find new uses for glycerol. In this study, we have shown that polymer films that include glycerol can absorb various amounts of polar solvents. Absorption of these solvents on the polymer matrix changed the elasticity and viscosity of the polymer. These types of polymers are important to develop for use in areas such as water remediation, filters, and drug delivery. Such applications require films that can to absorb large amounts of solvents while maintaining structural integrity.
Technical Abstract: Viscoelastic properties have been determined for poly(glycerol-co-glutaric acid) films synthesized from Lewis acid-catalyzed polyesterifications. The polymers were prepared by synthesizing polymer gels that were subsequently cured at 125 degrees C to form polymer films. The polymers were evaluated for extent of reaction before and after curing by FTIR. They were subsequently immersed in dimethylsulfoxide (DMSO), tetrahydrofuran (THF), water, methanol, and hexane for 24h. The amounts of solvent absorbed were monitored and recorded. Dependent upon the solvent used, the polymers were able to absorb 9.5 percent to 261 percent of its weight. The effects of the solvent absorption on the viscoelastic properties of the polyester films were evaluated by determining their elastic modulus, viscous modulus, tan delta, and complex viscosity by performing oscillatory frequency sweep experiments. The elastic modulus and viscous modulus were both higher for the dry polymers than the solvent-absorbed polymers. However, the polymer films were all higher in elastic character than viscous character. Therefore, tan delta less than 1 before and after immersion in solvents. Values for complex viscosity decreased with angular frequency for all of the polyesters tested in this study.