After several countries decided to ban plastic straws to tackle plastic pollution, finding an adequate replacement didn’t prove so simple. Multi-use alternatives, like metal straws, were too expensive for establishments and posed hygiene problems. Single-use straws made of paper seemed okay, but they get soggy upon prolonged contact with a liquid. Also, when used to drink carbonated beverages, they form more bubbles due to their surface properties.
Simply put, there wasn’t an alternative quite like plastic straws — until now. Researchers have come up with a new version of paper straws that are biodegradable and don’t get soggy.
Paper straws aren’t as eco-friendly as you may think to begin with. Their surface is coated with polyethylene (PE) or acrylic resin—the same materials used for making plastic bags, adhesives and paper cups. These coatings don’t just lead to soggy straws but are also non-degradable and can generate microplastics, a global environmental problem.
Researchers from the Korea Research Institute of Chemical Technology and the Sogang University wanted to address that, so they focused on developing sustainable paper straws that are biodegradable, perform much better than current paper straws, and can be easily mass-produced. They synthesized a biodegradable plastic and added cellulose nanocrystals to create a new coating material.
“Turning the plastic straw into a paper straw won’t immediately impact our environment, but the difference will be profound over time. If we gradually change from using convenient disposable plastic products to various eco-friendly products, our future environment will be much safer than we now worry about,” lead author Oh Dongyeop said in a statement.
The way forward for paper straws
Conventional paper straws don’t have a material that strongly attaches the plastic coating to the surface of the straw, which in turn isn’t uniformly coated. This makes the straws soggy when a liquid touches the uncoated part, the researchers explained. Bubbles also extensively form when straws are in touch with carbonated beverages
These limitations are now addressed by the new paper straws. They don’t get soggy or cause bubble formation in carbonated drinks as the coating material uniformly and strongly covers the surface of the straws. Also, the coating material is made of paper and biodegradable plastic, which means it will decompose and degrade completely.
The straws maintain their physical integrity in cold and hot drinks, the study researchers found. The straws also don’t get soggy when used to stir various beverages such as tea, water, milk, and carbonated drinks. The team also compared the degree of sogginess of the conventional straws and the one they created, as seen in the graph below.
The researchers also did a decomposition test in a marine environment to see how the new straws would perform. Regular straws didn’t decompose after 120 days, preserved their shape and lost 5% of their weight. In contrast, the new straws lost more than 50% of their weight after 60 days and decomposed completely after 120 days.
“The straws are not only anti-fizzing when used with soft drinks owing to their homogeneous and seamless surface coatings, but also highly water-resistant and tough owing to their watertight surfaces. All degradable components effectively decompose under aerobic composting and in the marine environment,” the researchers wrote.
The study was published in the journal Advanced Science.