Modification of absorbent poly(glycerol-glutaric acid) films by the addition of monoglycerides

Authors: Wyatt, Victor; BOAKYE, PRINCE - Delaware State University; Jones, Kerby; Latona, Nicholas - Nick; Liu, Cheng Kung; BESONG, SAMUEL - Delaware State University; LUMOR, STEPHEN - Delaware State University

Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary: Developing new outlets for glycerol would have a significant impact on the economics of biodiesel production if new value-added products made from glycerol can be identified. Glycerol is the major co-product produced from the process used to make biodiesel. Therefore, increased production of biodiesel created a need to find new uses for glycerol. In previous studies, we have shown that polymer films (bioplastics) made from glycerol can absorb various solvents based on the size, shape and polarity of the solvent. These types of polymers are important to develop for use in areas such as soil conservation, water remediation, filters, and drug delivery. In this study, we have modified the glycerol-based polymers with monoglycerides and, in doing so, improved the elasticity and absorption capacity of the films. Production and marketing of such new high-value products may decrease the net cost of biodiesel production and provide new products to improve the environment and human health.

Technical Abstract: Monoglycerides (MGs) have been incorporated into the matrix of poly-(glycerol-co-glutaric acid) films to investigate their effect on the thermal, mechanical, and solvent absorption properties of the resultant films. MGs were concentrated using a combination of solvent extraction and molecular distillation, resulting in a concentrate with 99.15 percent purity. The MG concentrate was predominantly monoolein (92.65 percent) and small amounts of monopalmitin, monostearin, and diolein. The films were made by first synthesizing polyester gels from glutaric acid and glycerol with the incorporation of 0, 2, 6, 10, 15 or 50 mole % of MG. The polymer gels were then cured at 150 degrees C for 24 h, forming clear, solid films with a yellow hue. Solvent absorption studies revealed that poly-(glycerol-co-glutaric acid-co-MG) films were able to absorb and resorb solvents better than poly-(glycerol-co-glutaric acid) films, albeit they had higher erosion levels. Thermogravimetric Analysis (TGA) showed that the incorporation MGs did not affect the thermal stability of the glycerol-based films. The MG-incorporated films had a 39-fold reduction in Young’s Modulus and 17-fold reduction in fracture energy when compared to the poly(glycerol-co-glycerol). Mechanical property studies also revealed that the incorporation of MGs increased the elongation % and reduced the tensile strength of poly(glycerol-co-glutaric acid) films. Correlation analysis revealed a strong linear relationship between Young’s Modulus and fracture energy (R squared = 0.9962), and between Young’s Modulus and tensile strength (R squared = 0.9972). This study proved that MGs can be successfully incorporated in the polymer matrix of poly(glycerol-co-glutaric acid) films to produce softer films with increased elongation and increased solvent absorption capacity.