Reviewed by Lexie CornerNov 1 2024
Recent research published in ACS Omega suggests that replacing the plastic layer in takeout containers with paper could enhance sustainability. Using mechanical tests and computer simulations, researchers identified paper-aluminum laminate designs that retain performance without sacrificing functionality.
By replacing plastic with paper, researchers have created a sustainable aluminum-backed packaging material prototype, shown here, that doesn’t compromise performance. Image Credit: Hamed Zarei.
Takeout containers reliably deliver meals from restaurant to table, but if made with foil-lined plastics, they are difficult to recycle. Polyethylene and aluminum laminates provide durability and moisture protection, but as consumers increasingly prefer packaging with less plastic and more eco-friendly materials, alternatives are needed.
To address this demand, Hamed Zarei and colleagues developed and tested various paper-aluminum laminates, assessing their strength and durability compared to standard polyethylene-aluminum packaging.
Zarei’s team initially created two types of paper-aluminum laminates:
- A machine-direction (MD) laminate, composed of aluminum and paper with fibers aligned parallel to the direction of machine loading (with the grain).
- A cross-direction (CD) laminate, made from aluminum and paper with fibers oriented perpendicular to the direction of machine loading (against the grain).
The researchers evaluated the tensile strength of MD and CD paper-aluminum laminates compared to traditional polyethylene-aluminum laminates by applying gradually increasing force to samples using laboratory machines. They also developed a digital model, validated with the tensile strength data, capable of simulating these stretching tests and accurately predicting the material's behavior under various conditions.
In the tests, the polyethylene-aluminum laminate exhibited greater stretchability without breaking compared to both paper-aluminum laminates. Between the two paper options, the MD paper laminate stretched further but developed cracks along the paper’s grain faster than the CD paper.
Through simulations using MD, CD, and a mixed MD/CD paper on their digital model, the researchers predicted that combining aluminum film with a paper layer made from both MD and CD fibers would provide mechanical properties close to those of conventional polyethylene-aluminum laminate.
Although the MD/CD paper-aluminum laminate has not yet been produced in the lab, this study offers valuable insights for packaging engineers working to develop sustainable materials with performance comparable to traditional options.
The authors acknowledge support from the Tuscany Region Development and Cohesion Fund.
Journal Reference:
Zarei, H., et al. (2024). Digital Twin Model of Paper–Aluminum Laminates for Sustainable Packaging. ACS Omega. doi.org/10.1021/acsomega.4c05798.