A biodegradable packaging material that bends but doesn’t break could be the answer to consumer demand for more environmentally conscious food delivery and storage. The challenge with bioplastics that break down easily in soil has been their lack of strength and flexibility. Researchers at Tuskegee University have taken inspiration from nature to try to change that.

Tuskegee University’s eggshell-based bioplastic film.The researchers looked at eggshells that are strong enough end to end to support weight, but are easy to crack down the middle. Adding shards of eggshell to bioplastic has yielded the researchers a material that exhibits the mechanical properties they were looking for, and will degrade in a soil-based environment.

The base polymer is 70% polybutyrate adipate terephthalate (PBAT), which is engineered to break down in soil within months, and 30% polylactic acid (PLA) made with cornstarch. The addition of egg shells to strengthen the material brought them to the nanoscale.

The eggshells were cleaned and ground in a solution of polypropylene glycol. The fragments then were exposed to ultrasonic waves, further breaking them down to nanoparticles. Small amounts of the nanoparticles were added to the PBAT/PLA solution with a resulting polymer that is more flexible than comparable bioplastic blends.

With some 76 billion eggs consumed in the U.S. annually, shell waste could become a resource, researchers say. The polymer could be used in food containers, film and grocery bags. The team is also looking into using the shell-based polymer for medical applications, including bone regeneration, wound healing and drug delivery.