When NatureWorks first had the idea, in 1989, to turn greenhouse gases, like carbon dioxide, into performance materials, the company looked to plants and nature for inspiration. The result, after deep thinking and innovation, was Ingeo – a polymer now found in products such as coffee capsules, diapers, cups, yogurt packaging, and electronics, and now, other 3D printed products thanks to NatureWorks’ Ingeo filament, best known generically as PLA. For example, these 3D printed golf tee markers printed for the 2021 Zurich Classic stop on the PGA tour.
More specifically, NatureWorks turns atmospheric carbon (the material from which trees, plants, and coral reefs, are built) into a portfolio of polylactic acid (PLA) performance materials.
“While we view carbon as a problem, nature views it as a resource and an essential building block,” explained Bryony Schwan, of The BioMimicry Institute.
NatureWorks’ first step in transforming these greenhouse gases into products involves using agricultural crops to sequester carbon – which effectively ‘fixes’ the gas as a simple plant sugar through the process of photosynthesis.
Currently, to create Ingeo, NatureWorks uses resources (‘feedstock’) such as dextrose and sucrose from cassava, corn starch, sugar cane, and beets, but is also assessing CO2 to lactic acid technology, and CH4 to lactic acid technology. Other industry-developing resources include lignocellulosics: sugars from bagasse, wood chips, switch grass and straw.
According to NatureWorks, “We are cautious about automatically viewing each next generation of feedstock as inherently more sustainable than the previous one. Whether it’s the first generation ‘bridging feedstock’ we use today, industrially sourced corn, or whether it’s cutting-edge concepts for turning CO2 or CH4 directly into green building blocks – bypassing the agricultural step altogether, at NatureWorks, we believe it’s vital to assure the integrity of the sustainability of every feedstock we use.”
“All feedstocks will have advantages and disadvantages, so the focus should be on committing to the continuous improvement of the best available feedstock option for that technology and sourcing region,” said Erin Simon, of Bioplastic Feedstock Alliance
The feedstock is put through a milling process where the starch (glucose) is extracted. Enzymes are then added, to convert the glucose to dextrose via a process called hydrolysis. Microorganisms then ferment this dextrose into lactic acid. A proprietary two-step process transforms lactic acid molecules into rings of lactide – a valuable chemical on its own and the core of NatureWorks’ customizable platform of chemical intermediates.
Through the process of polymerization, the lactide ring is opened and linked together to form the long chain of polylactide polymer NatureWorks calls Ingeo. This long chain of Ingeo PLA is then formed into pellets that are shipped around the world to NatureWorks’ customers and partners who transform them into a wide range of innovative products.
According to the NatureWorks website – manufacturing Ingeo produces approximately 80% less greenhouse gas and uses approximately 52% less non-renewable energy than traditional polymers, like polystyrene.
In terms of Ingeo’s end-of-life cycle – the biopolymer is made primarily of polylactic acid (PLA), a repeating chain of lactic acid, which undergoes a 2-step degradation process starting with disintegration, where the moisture and heat in the compost pile split the polymer chains apart, resulting in the creation of smaller polymers, and finally, lactic acid. The second step is biodegradation, where the microorganisms in the compost and soil consume the smaller polymer fragments and lactic acid as nutrients. Since lactic acid is widely found in nature, a large number of organisms metabolize lactic acid – resulting in carbon dioxide, water and humus, a soil nutrient.
According to a study conducted by Wageningen Food & Biobased Research, “Compostable products made with PLA disintegrated faster than orange peels or paper, and could not be recovered even after one composting cycle of 11 days.”