SOUTH KOREA – Researchers from the Creative Research Center for Nanocellulose Future Composites, at Inha University in Incheon, have developed bioplastic straws that have the right strength and stabilities and also ‘degraded significantly’ when left outside for two months.
Many countries have banned the use of single-use plastic straws, resulting in a shift to alternative ones, which have mostly been disappointing in experience as they absorb liquid and become soggy.
The inefficiency prompted the scientist – Dickens Agumba, Duc Hoa Pham, and Jaehwan Kim to overhaul the situation by developing a new type of bioplastic film from all-natural, degradable materials that are stronger than both paper and plastic straws.
The scientist noted that paper straws – often used as a substitute – have not been a resounding success: they “suffer from limited mechanical performance, are unsuitable for carbonated drinks, and often become soggy and collapse.”
Other than having an obnoxious user experience, they added that paper straws can also affect the flavor of beverages.
While there are other alternatives, such as metal straws, they also bear disadvantages, like high energy costs in production and emissions associated with ore mining to their manufacture and disposal options at the end of life. Cellulose-based straws, too, can be energy intensive to produce, they highlighted.
To create the new straws, the researchers blended lignin with either potato starch or polyvinyl alcohol (a more traditional bioplastic material) and then added citric acid.
The resultant in the form of a slurry is spread into a thin layer, rolled into a cylinder, and cured at over 350 F. The bioplastic naturally self-adhered at the seam, but heat treatment set it and made it even stronger.
In tests, the cylinders were stronger than those made of polypropylene plastic, yet still flexible. The bioplastic film also offered UV protection, which could be useful for other applications, such as a coating for greenhouse windows.
The researchers argue that their straws are economical and sustainable since starch and lignin, are readily available as byproducts of other industrial processes and could serve as cheap bioplastic ingredients (lignin, for example, is a waste material from paper or pulping processes and a side stream of bioethanol and bio-refinery concepts).
Lignin’s natural strength can be used to help overcome starch’s brittleness, especially when combined with a bio-based cross-linker, such as citric acid, say the researchers, as they combine the materials to create a plastic film.
“This green, economical, and scalable manufacturing process and the final products also demonstrate a closed-loop cycle, offering new avenues to engineer bio-based, hydrostable, strong, UV shielding, and biodegradable materials from economical and sustainable biomass,” they underscore in a publication of their findings.
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