- Dr. Oh Dongyeop commented about the background and significance of the research, the characteristics and advantages of the newly developed material, and future application plans for commercialization. 00:00~00:25 Background and significance of the research - Relative to their short usage time, plastic straws take a considerably long time to decompose. Furthermore, because of their sharp edges, they pose a significant threat to land and marine life when exposed to the environment. Although paper straws are emerging as an alternative to disposable plastic straws, which have been banned at restaurants and cafés, consumers are increasingly complaining about the quality of the paper straws that have replaced them and how their coating material is not fully decomposable in the environment. 00:27~01:21 Characteristics and advantages of the newly developed material (in comparison with conventional paper straws) - The newly developed straws are completely biodegradable because the coating material is made from only biodegradable plastic and materials derived from wood. In the marine environment, whereas regular paper straws and corn plastic straws did not fully decompose after six months, our straws decomposed completely. Regular paper straws have an uneven coating and consequently have the drawback of becoming soggy from the liquid seeping through the gaps in the coating. Also, their uneven coating stimulates excessive formation of bubbles in carbonated drinks. We have added cellulose nanocrystals to achieve a uniform coating on the biodegradable plastic coating material, preventing both the straws from becoming soggy and the formation of bubbles in soft drinks. 01:23~ Future applications in our daily lives and plans for commercialization - This technology improves the rate of biodegradation and enhances the moisture resistance of paper products. It thus can be widely applied not only to paper straws but also to other paper products such as paper tableware, paper cups, and paper boxes. Because paper products have been gaining popularity as eco-friendly products, we expect our products will improve consumer satisfaction with paper products and expand the market for other paper products.
Conventional plastic straws and corn plastic straws did not decompose after 120 days under marine conditions. They have preserved their shape and lost only 5% of their total weight. In the meantime, eco-friendly straws developed by the research team lost more than 50% of their weight after 60 days and decomposed completely after 120 days.
When used to stir a beverage in a cup, a paper straw is frequently bent slightly or delaminated. Due to its high mechanical rigidity in water, eco-friendly paper straw was observed to withstand a relatively heavy weight for 60 seconds under wet condition.
<NWSLUG />Eco-friendly paper straws that do not easily become soggy and are 100% biodegradable in the ocean and soil have been developed. The straws are easy to mass-produce and thus are expected to be implemented in response to the regulations on plastic straws in restaurants and cafés.
The paper straws that are currently available are not entirely made of paper alone. Straws made with 100% paper become too soggy when they come in contact with liquids and cannot function as straws. Accordingly, their surface should be coated. The most commonly used coating materials for paper straws are polyethylene (PE) or acrylic resin—the same materials used for making plastic bags and adhesives. Paper cups are also coated with the same materials as paper straws. A large number of previous studies have reported that polyethylene coating on discarded paper cups can disintegrate into small particles without being fully decomposed and become microplastics. Moreover, these paper products are made with paper and plastics (two very different materials) and thus it is difficult to recycle them.
Conventional paper straws are inconvenient to use. Upon prolonged contact with a liquid, they become soggy. Also, when these straws are used to drink carbonated beverages, many bubbles may form owing to their surface properties. Currently, polylactic acid (PLA) straws and rice straws are available in the market as alternatives to paper straws. However, PLA straws—also known as corn plastic straws—do not decompose well in the ocean. While rice straws decompose well in the environment, they have disadvantages, including higher prices, due to difficulties in their mass-production and their sharp cross-sections.
The joint research team of Dr. Oh Dongyeop and Dr. Kwak Hojung of KRICT and Professor Park Jeyoung of Sogang University have developed eco-friendly paper straws that are 100% biodegradable, perform better than conventional paper straws, and can be easily mass-produced.
Using their technology, the research team synthesized a well-known biodegradable plastic, polybutylene succinate (PBS)*, by adding a small amount of cellulose nanocrystals to create a coating material. The added cellulose nanocrystals are the same material as the main component of paper, and this allows the biodegradable plastic to firmly attach to the paper surface during the coating process.
* PBS (polybutylene succinate): Polyester-based biodegradable bioplastic with similar properties to those of petroleum-based polypropylene.
Conventional paper straws do not incorporate a material that will strongly attach the plastic coating to the surface of the straws. The surface of the straws thus is not uniformly coated with plastic, impeding their use. The most significant limitations this creates are that the straws become soggy when a liquid touches the uncoated part and bubbles extensively form when paper straws are left in carbonated beverages. This is because the uncoated part easily combines with water, whereas the coated plastic part has the property of repelling water, causing the carbonated drink to contact the uneven surface of the paper straws.
These limitations are overcome by the new paper straws developed by our research team; they do not become soggy easily or cause bubble formation in carbonated drinks because the coating material uniformly and strongly covers the surface of the straws. Also, the coating material is made of paper and biodegradable plastic and therefore will decompose and degrade completely.
The research team found that these eco-friendly paper straws maintain their physical integrity in not only cold drinks but also hot drinks. The team also found that the straws did not become soggy when used to stir various beverages such as water, tea, carbonated drinks, milk, and other drinks containing lipids, or upon prolonged contact with liquids. The degree of sogginess of the as-prepared paper straws and conventional paper straws was compared. The conventional paper straw was severely bent when a weight of approximately 25g was suspended after the straw was dipped in cold water at 5°C for 1 min. In contrast, the as-prepared paper straw did not bend as much even when the weight was more than 50g under the same conditions.
The newly developed straws decompose well, even in the ocean. In general, paper or plastic decomposes much more slowly in the ocean than in soil because of the ocean’s low temperature and high salinity, which impede growth of microbes. The research team performed a decomposition test in a marine environment by immersing the straw samples at a depth of 1.5–2 m on the coast near Pohang, South Korea.
Regular plastic straws and corn plastic straws did not decompose after 120 days. Conventional paper straws preserved their shape and lost only 5% of their total weight. In contrast, the straws developed by the research team lost more than 50% of their weight after 60 days and decomposed completely after 120 days.
“This technology is but a small step toward the direction we need to take in this era of plastic. Turning a plastic straw we often use into a paper straw will not 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 what we now worry about,” said the head researcher, Dr. Oh Dongyeop.
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KRICT was established as a government-funded research institute in 1976. KRICT has played a leading role in the development of the national chemical industry as it developed technologies for chemical and related fields of convergence, transferred chemical technologies to industries, produced professionals in the chemical field, and provided tremendous support for a variety of chemical infrastructures. Now we promise to reach new heights in chemistry and chemical engineering and continue our role in facilitating increased use of the knowledge from research. For more information, please visit KRICT’s website at https://www.krict.re.kr/eng/
This achievement was supported by the Nano·Material Technology Development Program through the Ministry of Science and ICT, the Basic Science Research Program through KRICT, and the Biodegradable Bioplastics Commercialization and Demonstration Project through the Ministry of Trade, Industry and Energy.
The research results were published in the international academic journal Advanced Science (IF:17.52) under the title ‘Biodegradable, Water-resistant, Anti-fizzing, Polyester Nanocellulose Composite Paper Straws’ on November 21, 2022, and are accessible to the public.
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Credit: Korea Research Institute of Chemical Technology (KRICT)
Caption: Conventional plastic straws and corn plastic straws did not decompose after 120 days under marine conditions. They have preserved their shape and lost only 5% of their total weight. In the meantime, eco-friendly straws developed by the research team lost more than 50% of their weight after 60 days and decomposed completely after 120 days.
Credit: Korea Research Institute of Chemical Technology (KRICT)
Caption: When used to stir a beverage in a cup, a paper straw is frequently bent slightly or delaminated. Due to its high mechanical rigidity in water, eco-friendly paper straw was observed to withstand a relatively heavy weight for 60 seconds under wet condition.
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