Recycling breaks new ground as PET plastics shattered by pure force

Plastic bottles in a pickup truck being taken for recycling Wikimedia Commons

Sometimes, all it takes to break the unbreakable is a good hit.

Scientists have discovered a cleaner, faster way to recycle one of the world’s most stubborn plastics, not with heat or chemicals, but with sheer mechanical force.

Polyethylene terephthalate (PET), a key material in bottles, packaging, and clothing fibers, is notoriously difficult to recycle because of its strong molecular bonds.

Tens of millions of tons are produced every year, and much of it ends up in landfills, adding to the growing global plastic crisis.

Now, researchers from the Georgia Institute of Technology have found a way to break down PET into its basic building blocks using mechanochemical recycling, a process that uses physical impacts rather than heat or harsh solvents.

The findings open a new path for recycling plastics more sustainably and efficiently.

Led by postdoctoral researcher Kinga Gołąbek and Professor Carsten Sievers from Georgia Tech’s School of Chemical and Biomolecular Engineering, the team used metal balls to hit solid pieces of PET with the same force they would experience inside a ball mill.

The mechanical impact generated enough energy to make PET react with sodium hydroxide (NaOH) at room temperature, breaking apart its molecular structure.

“We’re showing that mechanical impacts can help decompose plastics into their original molecules in a controllable and efficient way,” Sievers said. “This could transform the recycling of plastics into a more sustainable process.”

To understand what happens during these high-energy impacts, the researchers used controlled single-impact experiments and advanced computer simulations. They mapped how collision energy spreads through the plastic and triggers chemical reactions.

“These experiments showed changes in structure and chemistry of PET in tiny zones that experience different pressures and heat,” Gołąbek explained.

By mapping these transformations, the team revealed how mechanical energy alone can initiate fast and efficient chemical reactions. This discovery could reshape how recycling systems are designed.

“This understanding could help engineers design industrial-scale recycling systems that are faster, cleaner, and more energy-efficient,” she added.

Cracking the plastic code

Each impact created a small crater where the plastic absorbed the most energy. Inside these tiny zones, PET chains stretched, cracked, and softened , providing perfect conditions for reacting with sodium hydroxide.

Even without NaOH, some molecular bonds snapped simply from the force of impact, showing that mechanical pressure alone can drive chemical change.

The research also revealed that energy levels matter. Low-energy hits only disturbed the surface, while stronger impacts caused cracks and deformation that exposed more material for reaction.

“Understanding this energy threshold allows engineers to optimize mechanochemical recycling, maximizing efficiency while minimizing unnecessary energy use,” Sievers said.

Closing the loop

The team believes this method could lead to a future where plastics are recycled into their original components, not just downcycled into lower-grade products. “This approach could help close the loop on plastic waste,” Sievers said.

“We could imagine recycling systems where everyday plastics are processed mechanochemically, giving waste new life repeatedly and reducing environmental impact.”

Next, the researchers plan to test real-world plastic waste and apply the same principles to other hard-to-recycle materials. With millions of tons of PET produced annually, the potential environmental benefits are enormous.

“Improving recycling efficiency could significantly reduce plastic pollution and help protect ecosystems worldwide,” Gołąbek said.

Their full findings were published in the journal Chem.

MasterCard