VATIS UPDATE Article

Researchers at Tuskegee University (TU), the United States, have suggested that adding tiny eggshell pieces to bioplastic can create a biodegradable packaging material, a first-of-its-kind, which bends but does not break so easily. Vijaya K. Rangari, Boniface Tiimob and colleagues at TU, performed experiments with several plastic polymers. They decided upon a mixture containing 70% polybutyrate adipate terephthalate (PBAT), a petroleum polymer, and 30% polylactic acid (PLA), which is a polymer produced from cornstarch.

Unlike other petroleum-based plastic polymers, PBAT begins to degrade within three months after burial. This polymer mixture has many desirable properties, but the researchers wanted more flexibility from the material. Eggshells were used to create nanoparticles, as they are lightweight, porous and mainly composed of the easily decaying calcium carbonate. The eggshells were washed and ground up in polypropylene glycol.

The shell fragments were then broken down to nanoparticles, which were over 350,000 smaller than the diameter of human hair, upon exposure to ultrasonic waves. In a laboratory setting a small fraction of the nanoparticles, shaped like a card deck, was infused into the 70/30 PBAT-PLA mixture. The infusion of the nanoparticles made the polymer mixture 700% more flexible compared to the currently available bioplastics. This flexibility would be an ideal feature for grocery bags, retail packaging and food containers such as egg cartons.