Scientists are developing greener plastics – the bigger challenge is moving them from lab to market



File 20180813 2915 3vl524.jpg?ixlib=rb 1.1
Used once and done.
Michael Coghlan, CC BY-SA

Richard Gross, Rensselaer Polytechnic Institute

Synthetic plastics have made many aspect of modern life cheaper, safer and more convenient. However, we have failed to figure out how to get rid of them after we use them.

Unlike other forms of trash, such as food and paper, most synthetic plastics cannot be easily degraded by live microorganisms or through chemical processes. As a result, a growing plastic waste crisis threatens the health of our planet. It is embodied by the Great Pacific Garbage Patch – a massive zone of floating plastic trash, three times the size of France, stretching between California and Hawaii. Scientists have estimated that if current trends continue, the mass of plastics in the ocean will equal the mass of fish by 2050. Making plastics from petroleum also increases carbon dioxide levels in the atmosphere, contributing to climate change.

Much of my work has been dedicated to finding sustainable ways to make and break down plastics. My lab and others are making progress on both fronts. But these new alternatives have to compete with synthetic plastics that have established infrastructures and optimized processes. Without supportive government policies, innovative plastic alternatives will have trouble crossing the so-called “valley of death” from the lab to the market.

From wood and silk to nylon and plexiglass

All plastics consist of polymers – large molecules that contain many small units, or monomers, joined together to form long chains, much like strings of beads. The chemical structure of the beads and the bonds that join them together determine polymers’ properties. Some polymers form materials that are hard and tough, like glass and epoxies. Others, such as rubber, can bend and stretch.

A monomer of Teflon, a nonstick synthetic resin (top), and a chain of monomers (bottom).
Chromatos

For centuries humans have made products out of polymers from natural sources, such as silk, cotton, wood and wool. After use, these natural plastics are easily degraded by microorganisms.

Synthetic polymers derived from oil were developed starting in the 1930s, when new material innovations were desperately needed to support Allied troops in World War II. For example, nylon, invented in 1935, replaced silk in parachutes and other gear. And poly(methyl methacrylate), known as Plexiglas, substituted for glass in aircraft windows. At that time, there was little consideration of whether or how these materials would be reused.

Modern synthetic plastics can be grouped into two main families: Thermoplastics, which soften on heating and then harden again on cooling, and thermosets, which never soften once they have been molded. Some of the most common high-volume synthetic polymers include polyethylene, used to make film wraps and plastic bags; polypropylene, used to form reusable containers and packaging; and polyethylene terephthalate, or PET, used in clothes, carpets and clear plastic beverage bottles.

Recycling challenges

Today only about 10 percent of discarded plastic in the United States is recycled. Processors need an input stream of non-contaminated or pure plastic, but waste plastic often contains impurities, such as residual food.

Batches of disposed plastic products also may include multiple resin types, and often are not consistent in color, shape, transparency, weight, density or size. This makes it hard for recycling facilities to sort them by type.

Melting down and reforming mixed plastic wastes creates recycled materials that are inferior in performance to virgin material. For this reason, many people refer to plastic recycling as “downcycling.”

As most consumers know, many plastic goods are stamped with a code that indicates the type of resin they are made from, numbered one through seven, inside a triangle formed by three arrows. These codes were developed in the 1980s by the Society of the Plastics Industry, and are intended to indicate whether and how to recycle those products.


Filtre

However, these logos are highly misleading, since they suggest that all of these goods can be recycled an infinite number of times. In fact, according to the Environmental Protection Agency, recycling rates in 2015 ranged from a high of 31 percent for PET (SPI code 1) to 10 percent for high-density polyethylene (SPI code 2) and a few percent at best for other groups.

In my view, single-use plastics should eventually be required to be biodegradable. To make this work, households should have biowaste bins to collect food, paper and biodegradable polymer waste for composting. Germany has such a system in place, and San Francisco composts organic wastes from homes and businesses.

Designing greener polymers

Since modern plastics have many types and uses, multiple strategies are needed to replace them or make them more sustainable. One goal is making polymers from bio-based carbon sources instead of oil. The most readily implementable option is converting carbon from plant cell walls (lignocellulosics) into monomers.

As an example, my lab has developed a yeast catalyst that takes plant-derived oils and converts them to a polyester that has properties similar to polyethylene. But unlike a petroleum-based plastic, it can be fully degraded by microorganisms in composting systems.

It also is imperative to develop new cost-effective routes for decomposing plastics into high-value chemicals that can be reused. This could mean using biological as well as chemical catalysts. One intriguing example is a gut bacterium from mealworms that can digest polystyrene, converting it to carbon dioxide.

Other scientists are developing high-performance vitrimers – a type of thermoset plastic in which the bonds that cross-link chains can form and break, depending on built-in conditions such as temperature or pH. These vitrimers can be used to make hard, molded products that can be converted to flowable materials at the end of their lifetimes so they can be reformed into new products.

It took years of research, development and marketing to optimize synthetic plastics. New green polymers, such as polylactic acid, are just starting to enter the market, mainly in compost bags, food containers, cups and disposable tableware. Manufacturers need support while they work to reduce costs and improve performance. It also is crucial to link academic and industrial efforts, so that new discoveries can be commercialized more quickly.

The ConversationToday the European Union and Canada provides much more government support for discovery and development of bio-based and sustainable plastics than the United States. That must change if America wants to compete in the sustainable polymer revolution.

Richard Gross, Professor of Chemistry, Rensselaer Polytechnic Institute

This article was originally published on The Conversation. Read the original article.

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Sustainable shopping: take the ‘litter’ out of glitter


Jennifer Lavers, University of Tasmania

Shopping can be confusing at the best of times, and trying to find environmentally friendly options makes it even more difficult. Welcome to our Sustainable Shopping series, in which we ask experts to provide easy eco-friendly guides to purchases big and small. Send us your suggestions for future articles here.


Scientists often get a bad rap as party poopers. As a case in point, my colleagues and I have provided data on the impacts of balloon releases on marine wildlife.

So when glitter – a highly visible and easily obtained microplastic – comes under the microscope, you might be tempted to groan. The good news is that we’re not out to ruin the fun: with Mardi Gras around the corner (bringing a ubiquity of sparkling Instagrams), here’s how to find ecologically friendly glitter.




Read more:
Mixing glitter and protest to support LGBTQ rights


All glitter goes to the ocean

When something fun or common is revealed to be destructive it should be a point of pride in our society that we adjust, adapt and move on to safer alternatives.

It therefore makes sense to investigate what data exist for glitter, and to consider whether it’s time for a change in attitude. So, what is glitter?

Glitter is typically made from polyethylene, the same plastic found in plastic bags and a host of other products. Despite glitter’s popularity in everything from cosmetics and toothpaste to crafts and clothes, remarkably little is known about the distribution or impacts of glitter on our environment. As a scientist, that worries me. Glitter is incorporated into consumer products without any real knowledge of its safety.




Read more:
Ten ‘stealth microplastics’ to avoid if you want to save the oceans


In contrast, there are dozens of scientific papers on micro-bead scrubbers (tiny plastic beads), which originate from many of the same products (such as cosmetics and toothpaste).

Research on micro-beads suggests that around 8 trillion beads are released into aquatic habitats every day in the United States alone.

Data for glitter are not available, but given its widespread use the situation is likely to be similarly alarming. It’s far too small for waste treatment facilities to capture, so glitter goes straight into your local river and out into the ocean. Because glitter particles are typically 1 millimetre in size or smaller, they can be ingested by a range of creatures, including mussels.

Again, data on micro-beads can tell us why we should be worried about this: a recent study from Australia showed that toxic chemicals associated with micro-beads can “leach” into the tissues of marine creatures, contaminating their bodies. If mussels, fish and other animals are ingesting glitter and micro-beads, these contaminants likely also pose a risk to humans that consume them.




Read more:
Eight million tonnes of plastic are going into the ocean each year


Thankfully, science is here to help. A range of compostable, vegan, 100% plastic-free “bio-glitters” have been created and are readily available online. So, at your next event, you can celebrate in glorious, sparkly style while also educating passers-by about ocean conservation. (I assure you, this is very popular; I do it all the time and I’m the life of the party.)

What to look for

Mica, a naturally occurring sparkling mineral, is often offered as a non-plastic alternative to glitter. However, some brands, such as Lush, are now using “synthetic mica” (made in a lab) because mica mining has been associated with child labour, especially in India.

Some plastics labelled “bio-degradable” will only break down in industrial composting units, at temperatures over 50℃. This is very unlikely to happen in the ocean, so look for terms like “compostable” and “organic” instead. (For more information on the difference between bio-degradable, compostable and everything in between, this United Nations report is very comprehensive – just read the summary if you’re in a hurry).

Fortunately, eco-friendly glitter is becoming much easier to find around the world, and more suppliers are turning to cellulose and other plant-derived bases for their product. Wild Glitter‘s founder, like many in the industry, cites “watching a weekend’s worth of plastic glitter wash down the plughole after a festival” as the impetus to sell an “ethical, eco-friendly, cruelty-free way to sparkle”.

Eco Glitter Fun is a member of the Plastics Ocean Foundation, a global non-profit; Glo Tatts makes beautiful temporary glitter tattoos; and, for an Australian twist, Eco Glitter make their product from Eucalyptus cellulose.




Read more:
Film review: A Plastic Ocean shows us a world awash with rubbish


Bio-glitter can be incorporated into any product. Tasmanian soap maker Veronica Foale switched to bio-glitter last year and hasn’t looked back – if a small business in a rural area can do it, you can too!

The ConversationThis is the key to success in the battle against litter: not all changes are difficult and affordable alternatives do exist. Once you’ve mastered bio-glitter, embrace the next challenge – a bamboo toothbrush perhaps, or reusable Onya produce bags? Never stop learning. Go forth and sparkle responsibly.

Jennifer Lavers, Research Scientist, Institute for Marine and Antarctic Studies, University of Tasmania

This article was originally published on The Conversation. Read the original article.

Recycled Ink Cartridges to Build Bicycle Track in the West MacDonnell National Park


Here is a great recycling news story coming out of the Northern Territory in Australia – a 170km bicycle track is being built between Alice Springs and Simpson’s Gap in the West MacDonnell Ranges National Park, out of recycled plastics, including plastic from used printer ink cartridges. The bike track is a popular tourist destination in and around Alice Springs, so this upgrade is certainly a welcome one – especially given it that is being made out of recycled plastics. Full marks to the Northern
Territory government on this project – great news for all.

http://www.engadget.com/2010/06/13/recycled-ink-cartridges-used-to-build-bike-path-in-australian-na/

Visit Repeat Plastics Australia at:

http://www.replas.com.au/index.shtml