Research points to paper-aluminum laminates as viable plastic-free packaging alternative

A new study has found that replacing plastic layers in protective packaging with paper could offer a more sustainable option without sacrificing durability. Italian researchers developed different paper-aluminum laminates to test their mechanical properties and see if they could match the performance of conventional PE-aluminum packaging materials.

Traditionally, protective packaging relies on PE and aluminum laminates. PE provides durability and strength, while the aluminum foil acts as a barrier against moisture and light. However, with growing environmental concerns, consumers are pushing for alternatives that reduce plastic content in packaging. 

To address this demand, Hamed Zarei and his team focused on combining paper and aluminum to create sustainable laminates that retain the functional qualities of PE-aluminum packaging.

“Our investigation highlights the substantial potential of paper-based materials as environmentally friendly alternatives, particularly in contrast to aluminum-PE laminates,” say the researchers.

“Furthermore, integrating an innovative digital twin model, which combines experimental data and simulation, significantly advances our understanding and application of ‘laminated’ in the context of paper packaging design.”

Promise for sustainable packaging

The study, published in ACS Omega, developed two main types of paper-aluminum laminates: a machine-direction (MD) laminate, in which paper fibers run parallel to the machine loading direction, and a cross-direction (CD) laminate, where fibers run perpendicular to the loading direction. 

In tensile strength tests, they compared these laminates with common PE-aluminum laminates, stretching samples of each material with gradually increasing force on laboratory machines. 

Their findings showed that although PE-aluminum laminates could stretch further without breaking, the MD laminate offered greater tensile strength than the CD laminate, though it cracked more quickly along the paper grain. The CD laminate resisted grain cracking better. These insights led the team to predict that a hybrid paper-aluminum laminate using both MD and CD fibers could offer mechanical properties nearly identical to PE-aluminum laminates.

Using computer simulations, the researchers verified their experimental results, creating a model that could replicate these laminate stretching tests and reliably predict the material’s response under different scenarios. 

In response to EU regulations promoting aluminum packaging recycling, businesses are exploring the use of thinner aluminum layers and paper-based alternatives, particularly for products like chocolate. Companies are also incorporating sealing wax as an adhesive for aluminum packaging. While this wax is a much thinner glue than PE, it offers a more recyclable option.