New biodegradable plastic decays in a compost bin in a couple of years but it is expensive

According to researchers, the main challenge while creating bioplastic is not only to make it degradable, but also transparent, as this quality is often required by customers. CREDIT KTU / Juste Suminaite

Group of scientists at Kaunas University of Technology (KTU). Lithuania have created biodegradable plastic, which decays in a compost bin in a couple of years. Bioplastic created at KTU is transparent and all the materials in its composition are suitable for contact with food.

Globally, the amount of plastic produced in a year is roughly the same as the entire weight of humanity. Only 9% of it is recycled, and the rest is slowly degrading in the landfills. The plastic disintegration process takes from several hundred to a thousand of years; during the time plastic is disintegrating into microplastic particles, which get into the ground waters and from them – into our food and environment.

It is estimated that by 2050 in our oceans there will be more plastic than fish.

War with plastic waste is among the priorities of the current generation. The European Parliament has approved a law banning a wide-range of single-use plastic items, such as straws, cotton buds and cutlery by 2021, and numerous legislations around the world are being passed in order to control plastic waste. Scientists are also taking part in the movement while creating more environmentally-friendly solutions.

A team of researchers from the KTU Faculty of Chemical Technology have created a fully-compostable packaging for food products from bioplastic, which disintegrates with the help of microorganisms.

“We are used to get sandwiches, snacks, pastries, sweets and many other products in a paper bag with a plastic window. With a clear window on the front face, the products in the bag can be viewed easily. Although paper is biologically degradable, it is complicated to separate paper from plastic, and the package is considered non-recyclable and non-compostable. However, if we made the window from biodegradable plastic, it could be composted. Moreover, we could even use the bag for collecting biodegradable waste and put all into the compost bin together”, says Dr Paulius Pavelas Danilovas, the lead researcher of the team.

Compostability is a characteristic of a product that allows it to biodegrade under specific conditions under the influence of microorganisms.

“There are plenty of microorganisms in compost and they digest our plastic very well”, says Dr Danilovas.

According to EU standards, in industrial compost centres, which sustain the temperature of 580C, bioplastic degrades in half a year. However, in a compost bin at home, the process would take a couple of years.

Bioplastic created at KTU laboratories is made from cellulose – a natural material, the main building block of plant cells’ membranes. Usually derived from timber, cellulose is the most common biopolymer found in nature.

According to researchers, the main challenge while creating bioplastic is not only to make it degradable but also transparent, as this quality is often required by customers.

“Usually, to become fluid plastic needs to be heated. However, if you heat paper (which is also based on cellulose) it will not only not become liquid, but will also burn! We are excited to have found composites, which not only allow cellulose to turn into fluid condition but also are non-toxic, which is very important in all products related to food handling”, says Dr Danilovas.

He admits that being environmentally-friendly has its cost – the biodegradable package created at KTU is several times more expensive than usual. However, the growing number of eco-conscious users is encouraging industries to take an interest in biodegradable packaging alternatives.

Learn more: Lithuanian scientists created bioplastic for food packaging which degrades in a couple of years

 

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Combining natural rubber with bioplastic in a novel way results in a much stronger replacement for plastic

The new bioplastic and rubber blend devised by Ohio State researchers proved much more durable than the bioplastic on its own

New biodegradable ‘plastic’ is tough, flexible

The quest to keep plastic out of landfills and simultaneously satisfy the needs of the food industry is filled with obstacles.

A biodegradable replacement for petroleum-based products has to meet all sorts of standards and, so far, attempts at viable replacements from renewable sources have faced limited success due to processing and economic constraints. Among the obstacles, products to date have been too brittle for food packaging.

But new research from The Ohio State University has shown that combining natural rubber with bioplastic in a novel way results in a much stronger replacement for plastic, one that is already capturing the interest of companies looking to shrink their environmental footprints.

Almost all plastics – about 90 percent – are petroleum-based and are not biodegradable, a major environmental concern.

In a new study published in the journal Polymers, the research team reports success with a rubber-toughened product derived from microbial fermentation that they say could perform like conventional plastic. This new study highlights the greatest success in this area so far, according to the scientists.

“Previous attempts at this combination were unsuccessful because the softness of the rubber meant the product lost a lot of strength in the process,” said lead author Xiaoying Zhao, a postdoctoral researcher in Ohio State’s Department of Food Science and Technology.

The new study involved melting rubber into a plant-based thermoplastic called PHBV along with organic peroxide and another additive called trimethylolpropane triacrylate (TMPTA).

The end product was 75 percent tougher and 100 percent more flexible than PHBV on its own – meaning it is far easier to shape into food packaging.

Other research teams have combined rubber and PHBV, but the products have been too weak to withstand all the demands of a food package – from processing, to shipping, to handling in stores and homes, especially containers that are used for freezing and then microwaving, said the study’s senior author, Yael Vodovotz, a professor of food science and technology at Ohio State.

Increased flexibility, without a significant loss of strength, is particularly important when it comes to plastic films commonly used to package everything from fresh produce to frozen foods, she said.

While other attempts at making this type of rubber-enhanced bioplastic have reduced the strength of the PHBV by as much as 80 percent, only 30 percent of the strength was lost in this study – a much more manageable amount, Zhao said.

Toughness, which was improved, is different from strength, explained study co-author Katrina Cornish, an expert in natural rubber and professor of horticulture and crop science at Ohio State.

“Imagine trying to pull a block of concrete apart with your hands. That’s testing its strength. But karate chopping it with your hand or foot is testing its toughness – how easily it breaks,” Cornish said.

“You can never pull it apart, but if you’re strong enough you can break it.”

Much of the researchers’ current focus is on the potential use of various biodegradable – and otherwise environmentally conscious – materials they might use as fillers to further strengthen the mix. They’ve discussed using the “cake” left behind after a fellow researcher extracts oil from spent coffee grounds. Tomato skins are under consideration, as are eggshells.

“We want something that would otherwise go to waste that is sustainable and also relatively cheap,” Vodovotz said.

They’re even looking at the potential to attack two environmental problems at once, by seeing how invasive grasses that environmentalists are yanking out of waterways might play with the rubber-infused mix.

“We could dry them, grind them up and potentially use these grasses as a fibrous filler,” Vodovotz said.

Beyond packaged foods, a bioplastic could potentially be used in other food-related applications such as utensils and cutting boards.

And the researchers are looking to collaborate with colleagues outside of food science to consider other applications for their product, such as to create building materials, gloves for those working in food service, or parts for cars and airplanes.

As the team works to move its technology out of the lab and into the food industry, there will be many details to work out depending on a company’s individual priorities and concerns, Vodovotz said, and that may mean tinkering with the mix.

“As we get closer and closer to working with food manufacturers, there are specific questions our potential partners are asking,” Vodovotz said. “We have to be very careful about what we use in this process in order to meet their needs, and they have very specific parameters.”

Learn more: Study shows potential for Earth-friendly plastic replacement

 

The Latest on: Rubber-enhanced bioplastic
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    on April 9, 2019 at 4:19 am

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Eggshell nanoparticles could lead to expanded use of bioplastic in packaging materials

Adding eggshell nanoparticles to a bioplastic (shown above) increases the strength and flexibility of the material, potentially making it more attractive for use in the packaging industry. Credit: Vijaya Rangari/Tuskegee University

Adding eggshell nanoparticles to a bioplastic (shown above) increases the strength and flexibility of the material, potentially making it more attractive for use in the packaging industry.
Credit: Vijaya Rangari/Tuskegee University

Eggshells are both marvels and afterthoughts. Placed on end, they are as strong as the arches supporting ancient Roman aqueducts. Yet they readily crack in the middle, and once that happens, we discard them without a second thought. But now scientists report that adding tiny shards of eggshell to bioplastic could create a first-of-its-kind biodegradable packaging material that bends but does not easily break.

The researchers present their work today at the 251st National Meeting & Exposition of the American Chemical Society (ACS). ACS, the world’s largest scientific society, is holding the meeting here through Thursday. It features more than 12,500 presentations on a wide range of science topics.

“We’re breaking eggshells down into their most minute components and then infusing them into a special blend of bioplastics that we have developed,” says Vijaya K. Rangari, Ph.D. “These nano-sized eggshell particles add strength to the material and make them far more flexible than other bioplastics on the market. We believe that these traits — along with its biodegradability in the soil — could make this eggshell bioplastic a very attractive alternative packaging material.”

Worldwide, manufacturers produce about 300 million tons of plastic annually. Almost 99 percent of it is made with crude oil and other fossil fuels. Once it is discarded, petroleum-based plastics can last for centuries without breaking down. If burned, these plastics release carbon dioxide into the atmosphere, which can contribute to global climate change.

As an alternative, some manufacturers are producing bioplastics — a form of plastic derived from cornstarch, sweet potatoes or other renewable plant-based sources — that readily decompose or biodegrade once they are in the ground. However, most of these materials lack the strength and flexibility needed to work well in the packaging industry. And that’s a problem since the vast majority of plastic is used to hold, wrap and encase products. So petroleum-based materials continue to dominate the market, particularly in grocery and other retail stores, where estimates suggest that up to a trillion plastic bags are distributed worldwide every year.

To find a solution, Rangari, graduate student Boniface Tiimob and colleagues at Tuskegee University experimented with various plastic polymers. Eventually, they latched onto a mixture of 70 percent polybutyrate adipate terephthalate (PBAT), a petroleum polymer, and 30 percent polylactic acid (PLA), a polymer derived from cornstarch. PBAT, unlike other oil-based plastic polymers, is designed to begin degrading as soon as three months after it is put into the soil.

This mixture had many of the traits that the researchers were looking for, but they wanted to further enhance the flexibility of the material. So they created nanoparticles made of eggshells. They chose eggshells, in part, because they are porous, lightweight and mainly composed of calcium carbonate, a natural compound that easily decays.

The shells were washed, ground up in polypropylene glycol and then exposed to ultrasonic waves that broke the shell fragments down into nanoparticles more than 350,000 times smaller than the diameter of a human hair. Then, in a laboratory study, they infused a small fraction of these particles, each shaped like a deck of cards, into the 70/30 mixture of PBAT and PLA. The researchers found that this addition made the mixture 700 percent more flexible than other bioplastic blends. They say this pliability could make it ideal for use in retail packaging, grocery bags and food containers — including egg cartons.

Learn more: Eggshell nanoparticles could lead to expanded use of bioplastic in packaging materials

 

 

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Water heals a bioplastic

"What's unique about this plastic is the ability to stick itself back together with a drop of water," said Melik Demirel. Image: Demirel Lab/Penn State

“What’s unique about this plastic is the ability to stick itself back together with a drop of water,” said Melik Demirel.
Image: Demirel Lab/Penn State

A drop of water self-heals a multiphase polymer derived from the genetic code of squid ring teeth, which may someday extend the life of medical implants, fiber-optic cables and other hard to repair in place objects, according to an international team of researchers.

“What’s unique about this plastic is the ability to stick itself back together with a drop of water,” said Melik Demirel, professor of engineering science and mechanics, Penn State. “There are other materials that are self healing, but not with water.”

Demirel and his team looked at the ring teeth of squid collected around the world — in the Mediterranean, Atlantic, near Hawaii, Argentina and the Sea of Japan — and found that proteins with self-healing properties are ubiquitous. However, as they note in a recent issue of Scientific Reports, “the yield of this proteinaceous material from natural sources is low (about 1 gram of squid ring teeth protein from 5 kilograms of squid) and the composition of native material varies between squid species.”

So as not to deplete squid populations, and to have a uniform material, the researchers used biotechnology to create the proteins in bacteria. The polymer can then either be molded using heat or cast by solvent evaporation.

The two-part material is a copolymer consisting of an amorphous segment that is soft and a more structured molecular architecture. The structured portion consists of strands of amino acids connected by hydrogen bonds to form a twisted and/or pleated sheet. This part also provides strength for the polymer, but the amorphous segment provides the self-healing.

The researchers created a dog-bone shaped sample of the polymer and then cut it in half. Using warm water at about 113 degrees Fahrenheit — slightly warmer than body temperature — and a slight amount of pressure with a metal tool, the two halves reunited to reform the dog-bone shape. Strength tests showed that the material after healing was as strong as when originally created.

“If one of the fiber-optic cables under the ocean breaks, the only way to fix it is to replace it,” said Demirel. “With this material, it would be possible to heal the cable and go on with operation, saving time and money.

“Maybe someday we could apply this approach to healing of wounds or other applications,” he said. “It would be interesting in the long run to see if we could promote wound healing this way so that is where I’m going to focus now.”

Read more: Water heals a bioplastic

 

 

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Bioplastic – greener than ever

The use of biodegradable plastic packaging made of polylactic acid (PLA) is spreading. Since this year, PLA cups are available also in the ETH canteens. (Photo: Bo Cheng / ETH Zurich)

The use of biodegradable plastic packaging made of polylactic acid (PLA) is spreading. Since this year, PLA cups are available also in the ETH canteens. (Photo: Bo Cheng / ETH Zurich)

Polylactic acid is a degradable plastic used mostly for packaging. To meet the rising demand, ETH researchers have developed an eco-friendly process to make large amounts of lactic acid from glycerol, a waste by-product in the production of biodiesel.

Plastic waste is one of today’s major environmental concerns. Most types of plastic do not biodegrade but break up into ever smaller pieces while remaining a polymer. Also, most types are made from oil, a rapidly dwindling resource. But there are promising alternatives, and one of them is polylactic acid (PLA): it is biodegradable and made from renewable resources. Manufacturers use PLA for disposable cups, bags and other sorts of packaging. The demand for PLA is constantly rising and has been estimated to reach about one megaton per year by 2020.

The research groups of ETH professors Konrad Hungerbühler and Javier Pérez-Ramírez at the Institute for Chemical and Bioengineering are now introducing a new method to produce lactic acid. The process is more productive, cost-effective and climate-friendly than sugar fermentation, which is the technology currently used to produce lactic acid. The new method’s greatest advantage is that it makes use of a waste feedstock: glycerol.

Waste product of biofuel manufacturing

Glycerol is a by-product in the manufacturing of first-generation biofuels and as such is not high-grade but contains residues of ash and methanol. “Nobody knows what to do with this amount of waste glycerol”, says Merten Morales, a PhD student in the Safety and Environmental Technology group of professor Hungerbühler. This waste substance is becoming more and more abundant, with 3 megatons in 2014 expected to increase to over 4 megatons by 2020. Because of its impurity, glycerol is not suitable for the chemical or pharmaceutical industry. Moreover, it does not burn well and is thus not a good energy source. “Normally, it should go through waste water treatment, but to save money and because it is not very toxic, some companies dispose of it in rivers or feed it to livestock. But there are concerns about how this affects the animals.”

Making use of this waste feedstock by converting it into lactic acid already constitutes an advantage that makes the new method more eco-friendly.

Read more: Bioplastic – greener than ever

 

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