“Green” foam packaging developed from old cardboard

Photo of a cube made from the new packaging material

This cardboard-based foam reinforced with gelatin could be used as a sustainable packaging material. © Jinsheng Gou

Shop, send, throw away: countless packages are delivered every day. The packaging they contain protects the products being shipped, but creates a lot of waste, including lots of cardboard boxes. Researchers have now developed a new type of cushioning foam from such cardboard waste that can be reused as packaging material. The new recycled material is not only more environmentally friendly, but also more robust and insulates better than conventional plastic foam padding such as Styrofoam.

Online shopping is becoming increasingly popular and with globalization, more and more packages are traveling around the world. As a result, large amounts of waste paper in the form of cardboard envelopes and boxes pile up in our households and companies. Researchers have been trying for a long time to use and recycle this paper waste sustainably. The cardboard boxes could have a second life, for example, as robust but lightweight shipping material. This could then simultaneously replace the currently common plastic cushioning materials such as Styrofoam, which are based on petroleum resources and are therefore neither renewable nor biodegradable. A sustainable alternative could, for example, be light cellulose aerogels made from waste paper. However, in order to produce these from old cardboard, several chemical pre-treatment steps have been necessary. This costs time and money and is not exactly environmentally friendly.

Upcycling from paper pulp and glue

A research group led by Jinsheng Gou from the University of Forestry in Beijing was therefore looking for a simpler way to produce sustainable foam material based on recycled paper. To do this, the scientists first chopped up untreated cardboard scraps into a paste in a blender and then mixed this “paper smoothie” with either gelatin or polyvinyl acetate (PVA) glue. Gou and his colleagues poured these mixtures into cube molds, cooled them, and dried them frozen for three days. The two paper-based porous foams created in this way insulated better than currently common plastic foams such as Styrofoam, as the researchers report. In addition, the two new materials were very robust and provided excellent cushioning, effectively absorbing shocks and vibrations.

In a further step, Gou and his colleagues combined the pulp from waste paper with both gelatin and PVA glue and, after drying, also added a silicate-based liquid. This resulted in an impregnated waste paper foam that hardens when exposed to force. This high-performance version of the cardboard-based foam withstood even hammer blows without falling apart, as the researchers report. The new foam can therefore be used as a robust packaging material for extreme situations and can reliably protect even sensitive products in packages that are dropped from the air without a parachute.

Biodegradable padding

All three variants of the new upholstery packaging made from recycled paper are biodegradable, as the researchers emphasize. “We offer a simple and efficient way to create more environmentally friendly cardboard packaging materials,” says Gou. The process conserves resources overall and therefore protects the environment.

Source: Bin Zhang (Beijing University of Forestry) et al., ACS Sustainable Chemistry & Engineering, doi: 10.1021/acssuschemeng.3c06230

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