EPFL scientists have developed a new, PET-like plastic that is easily made from the non-edible parts of plants. The plastic is tough, heat-resistant, and a good barrier to gases like oxygen, making it a promising candidate for food packaging. Due to its structure, the new plastic can also be chemically recycled and degrade back to harmless sugars in the environment. Used in 3D printing, it could also provide a viable and stronger alternative to PLA, used for end-use applications such as packaging and bottles.
The development of degradable or recyclable polymers made from non-edible plant material referred to as “lignocellulosic biomass”, are part of an effort to address the challenges deriving from both fossil fuels and the accumulation of plastics in the environment. Producing competitive biomass-based plastics is not straightforward. In the article reporting the findings on the official EPFL website, EPFL’s Nik Papageorgiou points out that conventional plastics are so widespread because they combine low cost, heat stability, mechanical strength, processability, and compatibility – features that any alternative plastic replacements must match or surpass. And so far, the task has been challenging.
The EPFL scientists, led by Professor Jeremy Luterbacher at EPFL’s School of Basic Sciences, have successfully developed a PET-like plastic, which is biomass-derived plastic and meets the criteria for replacing several current plastics while also being more environmentally friendly.
“We essentially just ‘cook’ wood or other non-edible plant material, such as agricultural wastes, in inexpensive chemicals to produce the plastic precursor in one step,” said Luterbacher. “By keeping the sugar structure intact within the molecular structure of the plastic, the chemistry is much simpler than current alternatives.”
The technique is based on a discovery that Luterbacher and his colleagues published in 2016, where adding an aldehyde could stabilize certain fractions of plant material and avoid their destruction during extraction. By repurposing this chemistry, the researchers were able to rebuild a new useful bio-based chemical as a plastic precursor.
“By using a different aldehyde – glyoxylic acid instead of formaldehyde – we could simply clip ‘sticky’ groups onto both sides of the sugar molecules, which then allows them to act as plastic building blocks,” said Lorenz Manker, the study’s first author. “By using this simple technique, we are able to convert up to 25% of the weight of agricultural waste, or 95% of purified sugar, into plastic.”
While made from fossil fuels conventional PET (polyethylene terephthalate) is highly recyclable and it is the most used plastic in the world, with over 56 million tons produced in 2016. The well-rounded properties of this new PET-like plastic could allow them to be used in applications ranging from packaging and textiles to medicine and electronics. The researchers have already made packaging films, fibers that could be spun into clothing or other textiles, and filaments for 3D printing.
“The plastic has very exciting properties, notably for applications like food packaging,” says Luterbacher. “And what makes the plastic unique is the presence of the intact sugar structure. This makes it incredibly easy to make because you don’t have to modify what nature gives you, and simple to degrade because it can go back to a molecule that is already abundant in nature.”
Other contributors to this study include the EPFL Laboratory for Processing of Advanced Composites, the University of Natural Resources and Life Sciences (Austria), the Competence Center for Wood Composites & Wood Chemistry (Austria) and the EPFL Industrial Energy Systems Laboratory.