Scientists Create 100% Biodegradable Paper Straws That Don’t Get Soggy

Eco enthusiasts who've already eschewed straws may wonder what the point is in developing new ones. But for anyone unable or unwilling to abide by a soggy paper straw, a strong yet fully biodegradable one has been invented by scientists at the Korea Research Institute of Chemical Technology (KRICT).

The discovery comes from the joint research team of Dr. Oh Dongyeop and Dr. Kwak Hojung of KRICT and Professor Park Jeyoung of Sogang University.

The new straws are easy to mass-produce and could fill the gap between consumers wanting a rigid straw and regulations on plastic straws in restaurants and cafés. Changing consumer habits and weaning the world off straws would be the best-case scenario (with an exception for those who rely on straws for health and other reasons). But in the meantime, a truly biodegradable straw that can stand up to the complaints of plastic-straw lovers could make a difference. Who can lament that the eco-radicals have come for the straws when there’s a perfectly viable, eco-friendly replacement?

As noted in a paper detailing the invention of the new straws, traditional single-use straws are particularly bad in the marine environment because of the harm they do to sea animals. “In addition, they are rarely recycled because they are small, which makes collection difficult; they are also non-degradable." Some straw manufacturers now make their products with bioplastics, like polylactic acid made from corn, but as the study authors note, polylactic acid (PLA) straws are not marine-degradable.

Plastic straws became a rallying point for environmentalists, much in thanks to the iconic event of an unfortunate sea turtle with a straw deeply submerged in its nose. Renouncing plastic straws seems like an easy first step in recognizing—and giving up—single-use plastic items that are not essential for everyone. Bans on plastic straws are now fairly widespread, and thus, enter the paper straw.

Paper straws make sense on paper, so to speak. Yet most currently available paper straws have a dirty little secret. Since 100% paper would result in a straw too soaked to sip from, most of them have a coating of polyethylene (PE) or acrylic resin, the same materials used for making plastic bags and adhesives. 

This is the bane of paper cups as well. Numerous studies have found, according to the KRICT team, 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.” 

Rice straws and straws made of PLA are available as alternatives to paper straws. However, the KRICT scientists discovered that these do not decompose well in the ocean. Meanwhile, rice straws decompose well in non-marine environments, but they are harder to manufacture and are more expensive. 

The new straws, on the other hand, rely on a well-known biodegradable plastic, polybutylene succinate (PBS) to which the team added a small amount of cellulose nanocrystals to create the coating material. Most simply put, cellulose is plant fiber. Since the added cellulose nanocrystals are the same material as the main component of paper, they provide optimal attachment of the PBS to the paper surface during the coating process. 

The researchers note: “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.”

The newly devised straws resist sogginess in cold drinks as well as hot drinks. They retain their rigidity when used to stir water, tea, carbonated drinks, milk, and other drinks with lipids, and they do so upon prolonged contact with liquids. In comparison testing, the team found that after soaking in cold water for one minute, a conventional paper straw was notably bent by a weight of approximately 25 grams. The new paper straw fared much better, even when the weight was increased to more than 50 grams under the same conditions.

But perhaps the most important characteristic is the new straw’s marine biodegradability. The claim gets thrown around loosely, and all too often something billed as biodegradable takes an inordinate amount of time to actually degrade.

Since the coating material is made of paper and biodegradable plastic, the researchers claim that it will decompose and degrade completely 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 the growth of microbes,” explains a press statement from KRICT. “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.”

As shown in the image below, regular plastic straws and corn plastic PLA straws did not decompose after 120 days. Conventional paper straws preserved their shape and lost only 5% of their total weight. Meanwhile, the new straws lost more than 50% of their weight after 60 days and decomposed completely after 120 days.

There has been no shortage of debate about the importance, or lack thereof, of ditching plastic straws. In the big picture, with Big Ag devouring habitat and fossil fuel companies perpetuating their wreckless ways, etc, is giving up plastic straws really going to make a difference? Given that the United States uses millions of single-use plastic straws a day and that plastic straws are among the top 10 contributors to plastic marine debris across the globe, why wouldn’t we want to stem the tide?

“This technology is but a small step toward the direction we need to take in this era of plastic,” says lead researcher, Dr. Oh Dongyeop. “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.” 

The best solution for those who have the option is to give up using straws altogether. But having a better alternative out there can provide a reasonable, eco-friendly choice for people who need to use straws—and might at least tame the damage made by straw users who just don’t care about marine plastic pollution or straws lodged in the noses of turtles.

To see the chemistry behind the project, read the research in Advanced Science.