Usually, when we think of 'straw', hard plastic straws come to mind first.
Strong straws that do not bend well and do not get wet.
However, these hard straws are no longer easy to find.
The current reality is that we are faced with soft paper straws more often than hard straws.
This is because eco-friendly materials that are easily decomposed in nature are used instead of plastics that cause environmental problems.
Originally, all plastic straws should have disappeared from all restaurants and cafes from the end of this month, but as the government gave more grace period, the uncomfortable companionship of paper and plastic continued until next year.
It is a natural change for the environment, but it is not a perfect change.
This is because paper straws definitely have their downsides.
The biggest drawback is the durability of paper straws.
This is because paper straws get wet and soggy easily when you put them in drinks.
In other words, a straw cannot function as a straw.
This is why many consumers who visit cafes complain about paper straws.
We know that paper straws are eco-friendly, but it is also true that they do not play the role of straws.
Paper straws, why do they get soggy so easily?
How are paper straws made?
Is it 100% paper?
Not like that.
Most of the straws are made of paper, but in the final coating process, polyethylene (PE), a plastic material, is coated.
It is a process to make straws more durable, and at this time, various problems that we experience arise.
Polyethylene is hydrophobic*, not friendly to water.
On the other hand, paper is hydrophilic** that is close to water, but since materials with completely different properties meet and combine, 100% perfect coating is not achieved.
It's a minute difference that we can't see at all, but this minute difference causes moisture.
This is because the entire straw becomes damp as the beverage penetrates into the uncoated part and is absorbed into the paper.
Even if tetraports are installed on the breakwater to block waves, the beverage enters through the gaps in the coating film, just as sea water enters between the gaps in the tetraports.
There are also other problems.
Recycling is difficult because two materials with completely different properties are combined and used.
Paper should be recycled as paper and plastic as plastic, but plastic-coated paper straws are difficult to recycle either way.
Also, from an environmental point of view, even if the paper component of the straw is decomposed in nature, there is a problem that polyethylene, a plastic material, does not decompose and remains as microplastic.
To solve these problems, straws using bioplastics have appeared, such as polylactic acid (PLA) straws called corn straws and rice straws.
However, corn straws do not decompose well in the ocean, and rice straws are expensive and have a sharp cross section, so they have not been widely commercialized.
Bioplastics are also not a solution.
If you make a straw with only bioplastic itself, it is a problem because it does not decompose well, and if you use bioplastic as a coating agent, it penetrates water better than general plastic and makes a more damp straw.
Eco-friendly straws that don't get wet?
A research team in Korea has presented the results of a study that solved this problem.
A domestic joint research team, including Dr. Dong-yeop Oh and Dr. Ho-jeong Kwak of the Korea Research Institute of Chemical Technology, developed a straw that is highly durable like existing plastic straws while being easily decomposed.
As a coating agent, polybutylene succinate (PBS), a biodegradable bioplastic, was used, and the weaknesses of existing bioplastic coating agents were overcome.
Cellulose nanocrystal, a natural material obtained from plants, was the key.
While acting as a kind of adhesive, it also strengthened the self-durability of polybutylene succinate (PBS) and made it possible for PBS to coat paper straws seamlessly.
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a, In the case of using only PBS bioplastic – the cross section is uneven, uneven, and has many gaps.
b.
When PBS and CNC (cellulose nanocrystal) are mixed - the cross section is more even than a and there are fewer gaps.
c.
Precise blending of PBS and CNC through a chemical process – most even and least voids.
The research team repeated the experiment of soaking the developed straw in cold water and then taking it out and compared it to the paper straw, and the newly developed straw was much more durable.
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In addition, to see the decomposition rate in the actual natural environment, straw samples were immersed in the waters near Pohang and observed for about 120 days.
As a result, ordinary plastic straws and corn straws did not decompose at all, while paper straws degraded by about 5%.
On the other hand, the newly developed straw was decomposed by more than 50% after 60 days and completely disappeared after 120 days.
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Although the price is about 10% more expensive than before, it has the advantage of being able to catch two rabbits in terms of environment and practicality.
Research Director Dr. Dongyeop Oh said, "This technology is an example of the direction we need to move forward. Changing plastic straws to paper won't have an immediate effect, but it will be different in the future." He asked for small actions for the environment. .
<References>
Hojung Kwak, Hyeri Kim, Seul-A Park, Minkyung Lee, Min Jang, Sung Bae Park, Sung Yeon Hwang, Hyo Jeong Kim, Hyeonyeol Jeon, Jun Mo Koo, Jeyoung Park, Dongyeop Oh, "Biodegradable, Water -Resistant, Anti-Fizzing, Polyester Nanocellulose Composite Paper Straws", Advanced Science (2022), doi.org/10.1002/advs.202205554