Of the 138 million tons of landfilled waste collected in the United States in 2015, 22% and 18.9% consisted of food and plastic respectively. Reducing the amount of both food and packaging waste therefore represents a significant opportunity in improving the environmental sustainability of our food supply. Manufacturers commonly add metal chelators to foods to increase shelf life and reduce food spoilage & waste due to oxidative degradation and microbial spoilage. To address consumer demand for cleaner labels, nonmigratory active packaging with metal chelating moieties bonded to traditional petroleum-based plastics has been researched. We have demonstrated the ability to delay oxidative degradation of ascorbic acid in simulated beverage matrices using a polypropylene based chelating active material. However, an opportunity remains in applying this technology to biodegradable materials. In this work, polylactic acid (PLA), a biodegradable polymer, was grafted to maleic anhydride (MA) in a mass ratio of 91.5: 0.5: 8 of PLA: dicumyl peroxide: MA via radical polymerization in a reactive extruder to form PLA-g-MA. PLA-g-MA pellets were blended with PLA in a 90:10 mass ratio and functionalized using cationic polymerization to introduce iminodiacetic acid chelating ligands (PLA-g-IDA). Grafting was confirmed using ATR-FTIR, with the formation of new characteristic bands associated to the introduction of maleic anhydride, amines, and carboxylic acid moieties. SEM micrographs and surface contact angle were used to characterize the PLA-g-MA and PLA-g-IDA films. Metal chelating capacity towards Fe (III) and Cu (II) were determined by the colorimetric Ferrozine and Zincon assays. This work demonstrates the capability of creating nonmigratory metal chelating material using biodegradable polymers with the long-term goal of reducing the environmental impact of both food waste and food packaging.

Synthesis of biodegradable nonmigratory active packaging via reactive extrusion

2019 Spring National Meeting

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