We often come up with different products, such as grocery bags, packaging materials and water bottles, that are labelled as biodegradable or compostable, meaning they will eventually decompose naturally. Composting is a powerful way to recycle waste products that might otherwise be thrown into a landfill. The result is very beneficial – decomposed materials can be used to improve soil fertility. Compost is rich in nutrients that crops, garden plants and trees can readily devour. To claim that a product is fully compostable, the product has to comply with the European standard EN 13432. The specifications require the material to fully biodegrade in a specific time frame, leaving no harmful residues behind. The standard also sets out clear requirements for the surroundings in which this process takes place. The standard constantly evolves, leaving plenty of room for the development of new technologies that ensure biodegradable and compostable products. Biodegradable and compostable plastics are supposed to reduce the pollution problem posed by plastics if they are correctly disposed of. Poor management or bad waste practices can cause a large percentage of waste plastic to reach the ecosystem in an uncontrolled way. To counter these issues, the EU-funded REBICOM project has developed a new way to reduce standard thermoplastic polymers, either of fossil or renewable origin, to their constituent building blocks. The process also allows products to be efficiently and safely recycled into high-quality new plastics. The project has been led by Innovative Film Solutions, a plastic film producer in Spain.
Plastic-eating enzymes to the rescue
Innovative Film Solutions has produced a new range of plastic films as a sustainable, compostable alternative to conventional films for packaging. Researchers focused on an enzymatic technology that accelerates plastic breakdown. REBICOM coordinator Joaquín Buendía explains: “Plastics take hundreds if not thousands of years to degrade, breaking down into ever-smaller pieces. Adding certain compounds to plastics could act as a culture for microorganisms. The enzymes secreted by organisms initiate material depolymerisation, feed on carbon bonds, thereby speeding up biodegradation.” Researchers encapsulated certain enzyme complexes in a polyolefin matrix (polypropylene and polyethylene), obtaining a masterbatch that was incorporated into the formulation of plastic films during the production process. “The plastic films carry within an inactive load that is 100 % recyclable. When these plastic films end up in the environment in contact with microorganisms, their load triggers an enzymatic reaction that converts them into biodegradable in a relatively short period of time, given the proper temperature and humidity levels,” adds Buendía. The new intelligent plastics that break down naturally are a flexible alternative to conventional films for plastic packaging. Importantly, they do not increase the material production costs or densities.
Making the leap to industrial-scale manufacturing
Once researchers succeeded in introducing the enzyme complexes in the plastic film formulations in the laboratory, they continued to prove the technology at scale. To achieve their goal, they adapted several parameters in the manufacturing process, including the temperature, particle sizes, load dispersion and subsequent treatments. “The prototype films obtained meet the needs of the plastic packaging film market and comply with the European standard EN 13432 as well as with the European legislation for food contact materials. These advances open up an entirely new opportunity to produce biodegradable, compostable and recyclable plastic films at a low cost without modifying current plastic processing methods,” concludes Buendía.
REBICOM, compostable, plastic film, enzyme, packaging, Innovative Film Solutions, biodegradable