Bio-based materials are important to many industries, and one common usage can be found in food packaging. Recent efforts involving NDSU researchers have resulted in food packaging being developed from bio-based polymers. One of the most promising is polylactic acid, also known as PLA.
Rather than synthetic polymers, biodegradable polymers have become a preference, according to Center for Sustainable Materials Science (CSMS) researcher Dilpreet Bajwa, NDSU professor of mechanical engineering, and Center for Regional Climate Studies (CRCS) collaborator Kerry Hartman, a Nueta Hidatsa Sahnish College (NHSC) environmental science faculty member and academic dean.
The challenge with the PLA-based films is that some of its characteristics, including barrier and anti-microbial properties, are not sufficient for food packaging applications. Thanks to a North Dakota Established Program to Stimulate Competitive Research (ND EPSCoR) RII Track-1 Emerging Areas Seed Award, this past year, Hartman and Bajwa have been collaborating on ways to enhance PLA film characteristics.
As part of the process, students from NHSC came to NDSU to learn about research techniques and the benefits of bio-based materials on the environment, expanding their education and workforce development options.
“PLA is a strong, stiff polymer, but it cracks easily and has a narrow processing temperature range,” Bajwa said. “Our goal for the research was to improve the properties while keeping it 100 percent bio-based.”
They began by adding cellulose nanocrystals, tiny particles from trees and plants with higher strength than glass or Kevlar fibers, that increased the polymer’s strength, cracking resistance and thermal stability.
The biggest challenge?
“The nanocrystals only work when they’re dispersed evenly throughout the PLA,” Bajwa said, “And we had to identify a different method of incorporating them into the PLA since the cellulose nanocrystals naturally clump together.”
Industry applications
After several attempts with limited success, Bajwa and Hartman, along with NDSU and NHSC students, found a method of treating the nanocrystals to achieve even dispersion.
“I came from industry, so I’m always interested in the commercial applications for research,” Bajwa said. “This work provides a simpler method for industry to improve properties of PLA.”
Not only are packaging companies interested in this research but so is the U.S. Forest Products Laboratory in Madison, WI, which supplied the cellulose nanocrystals.
If successful, this research would open industry doors for added renewable forest products.
What’s next?
“We’re working with two polymer packaging companies to test the cellulose nanocrystals-enhanced PLA,” Bajwa said. “We hope to pursue a patent that would make the technology available to the food packaging industry. Beyond that, we will test nanocrystals in other polymers besides PLA. There are many high-end applications in other industries that may use this research.”
The mission of ND EPSCoR is to increase the competitiveness of North Dakota for merit-based grants and contracts in support of research in the disciplines of science, technology, engineering and mathematics.
Funding is provided by the State of North Dakota and NSF EPSCoR Research Infrastructure Improvement Program Track-1 (RII Track-1) Cooperative Agreement Award OIA-1355466.
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