Foam made from recycled cardboard, Sustainable foam for packaging

Researchers at Beijing Forestry University have developed a process for using recycled cardboard to produce a sustainable, energy-absorbing foam that they say is ideal for packaging products for shipping.
Image: Beijing Key Laboratory of Wood Science and Engineering

Researchers tout sustainable packaging foam made from waste cardboard

Researchers in Beijing have developed an environmentally friendly cushioning and insulating foam made entirely from recycled cardboard that they say offers a sustainable, plastic-free packaging alternative to the shipping industry.

This new biodegradable foam is said to have low density (0.065–0.081 g/cm³), high porosity (>92%), low thermal conductivity (0.044 W/mK), excellent mechanical properties, and outstanding cushioning properties. The researchers –– who received funding from the Beijing Key Laboratory of Wood Science and Engineering (part of Beijing Forestry University) –– said they used a simple green method using wastepaper without any chemical pretreatment as the raw material.

Sustainable Foam as a Packaging Alternative

Some propose using lightweight, cellulose aerogels as a more eco-friendly foam packaging option (versus, for example, expanded polystyrene foam) but current methods to produce them from wastepaper require several chemical pretreatment steps. The team in Beijing wanted to find a simpler approach to sustainable packaging solutions.

Jinsheng Gou headed the effort, along with several of his colleagues. Gou, who holds a Master's degree in Packaging Engineering and a PhD degree in Wood Science & Technology, is currently a visiting associate professor at The University of British Columbia in Canada. He also has taught at Beijing Forestry University since 2005. In an email interview, Gou said they’ve been working on this project for roughly five years.

Jinsheng Guo, Expert in Sustainable Packaging Management

Jinsheng Guo, who is leading the effort, is currently teaching at The University of British Columbia in Canada. Image: Beijing Key Laboratory of Wood Science and Engineering

“The discovery was born out of a collective effort to address sustainability concerns in packaging materials,” he said. “Our goal was to repurpose recycled cardboard into a viable alternative for traditional foam.”

In an article published recently in ACS Sustainable Chemistry & Engineering, Gou and his colleagues wrote “The porous structure and the reinforced cell skeleton formed by the wastepaper fibers coupled with PVA (polyvinyl acetate) and gelatin, respectively (“bridge-linking” and “membrane-linking” structure), give the foam excellent coordination between thermal insulation and energy absorption properties.” Such properties are typically considered incompatible with each other in conventional cushioning foam materials.

The team used a blender to break down their cardboard scraps and then mixed them together with either PVA glue or gelatin. They poured the mixtures into molds, cooled them down and then freeze-dried them to create cushioning foams. Gou said the foam can be produced from all kinds of paper and cardboard materials, noting that they also have successfully used corrugated paperboard waste.

Process Can Produce Highly Energy-Absorbent Foam

Production and properties of energy-absorbing foam

This shows some of the ingredients and steps involved in transforming cardboard waste into a usable packaging foam.

Furthermore, they report, they successfully produced a biodegradable cushioning packaging material with ultrahigh energy absorption by impregnating a shear thickening fluid (STF) into wastepaper-based foam. Such properties can make the resulting foam suitable as cushioning material for product delivery in extreme environments, such as parachute-free airdrops.

The findings demonstrate that when the external impact velocity surpasses the critical shear rate of STF, the increased mass fraction and content of STF can enhance the energy absorption properties of the wastepaper-based foam, significantly enhancing its dynamic cushioning performance. Their findings indicate that STF can decrease the maximum impact acceleration by up to 85%.

Gou confirmed that the team then created a heavy-duty version of their wastepaper foam by combining the pulp, gelatin, PVA glue, and a silica-based, non-Newtonian fluid that results in a robust foam. He said this version of the cardboard-based foam withstood hits from a hammer without falling apart.

Various attributes of the resulting eco-friendly foam

The researchers tout various attributes of their resulting foam –– highly sustainable, good energy absorption and excellent insulating properties. Image: Beijing Key Laboratory of Wood Science and Engineering

Despite significant progress, he acknowledges that challenges remain in scaling up production and ensuring cost-effectiveness, raw material availability and finial product performance for specific application sector. “Commercial viability is a key focus, and we are actively exploring partnerships to address this aspect.”

Advancing to the next stage involves refining the production process and exploring potential corporate collaborations. A corporate sponsor, he noted, could indeed facilitate the transition to a commercially viable product.

Work continues on the project in Beijing, even as Gou is working in British Columbia. “The academic environment provides valuable insights and resources for further research and development.”

Their full report –– “Biodegradable Wastepaper-Based Foam with Ultrahigh Energy-Absorbing, Excellent Thermal Insulation, and Outstanding Cushioning Properties” –– is dated Nov. 28, 2023, and can be accessed here.