DISCOVERY AND UTILIZATION OF BIOACTIVE COMPONENTS FROM NEW CROPS AND AGRICULTURAL CO-PRODUCTS
Location: Functional Foods Research Unit
Title: Glycerol citrate polyesters produced through microwave heating
Submitted to: Journal of Applied Polymer Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 2, 2011
Publication Date: September 5, 2012
Citation: Tisserat, B., Harry O Kuru, R.E., Hwang, H.-S., Mohamed, A.A., Holser, R.A. 2012. Glycerol citrate polyesters produced through microwave heating. Journal of Applied Polymer Science. 125(5):3429-3437.
Interpretive Summary: Petroleum-based-plastics account for 3.7 trillion dollars annual sales with 80% of the output polypropylene, polyethylene, polycarbonate and poly-vinyl chloride. Bioplastics account for only 3% of the worldwide total of plastics manufactured. One of the major problems with bioplastics is their cost. Frequently, they are 2 or 3 times the cost of petroleum-based plastics. There is a great need for new cost bioplastics. Glycerol citrate copolyesters (i.e., citric acid and glycerol blends) offer a new bioplastics that is inexpensive to produce. This paper demonstrates the use of microwave heating technique to rapidly produce these polymers quickly and effectively. Utilization of this technology should allow for development and evaluation of glycerol citrate copolyesters formulations and speed development of the use of these polymers to the commercial scale.
The influence of various heating methods without catalysis to prepare copolyesters from citric acid:glycerol blends were studied. In the presence of short term microwave treatments, i.e., 60 sec at 1200 W, blends of glycerol and citric acid invariably formed solid amorphous copolyesters. Fourier transform infrared (FT-IR) spectroscopy showed that citric acid and glycerol blends can form highly stable polymers composed of ester bonds. Copolyesters of glycerol and citric acid were studied with differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The copolyesters were found to be thermally stable (up to 313 oC). The glycerol citrate polyester polymers exhibited the least retrogression in water, more in acid solutions (0.1 to 1.0 M HCl) and the most deterioration in strong alkaline solutions (0.1 to 1.0 M NaOH) after 72 hrs soakings.