Tag Archives: microplastic

Plastic replacements: some new conSQUIDerations

Posted on March 27, 2019 by | 3 comments

The amount of plastic that has been produced to date now exceeds 8300 million metric tonnes (Mt). To put this into perspective, the average blue whale weighs approximately 180 Mt, thus 46 million blue whale’s worth of plastic has been produced since humans started commercializing plastics in 1950. Our society had become extremely dependent on plastic products and synthetic (petroleum- based) textiles which cause serious consequences such as microplastic and microfiber pollution as I’ve discussed in previous blog posts.

Figure 1. Size reference for blue whales. Wikipedia Commons

Bioplastics have more recently taken the stage as a potential avenue for replacing petroleum-based plastics. Biologically based polymers have structural elements such as helices, β-turns, β-sheets and coils which provide structural integrity and resilience and can replicate the desirable polymeric interactions in plastics. Additionally, a lot of new material is being developed based on the protein polymers that are naturally occurring in biological systems (including ourselves).

Figure 2. Fibrous protein polymers have molecular architecture that can include (i) helices and coils, (ii) β-turns and β-spirals, and (iii) β-sheets. Source

Video 1. SRT- coated fabrics that self-heal in water.

Squid ring teeth (SRT) are an especially promising candidate for making functional fibres and films due to its strength, conductivity and self-healing properties. The SRT are located inside the suction cups of the tentacles of squids and are composed of a naturally occurring protein complex. Fortunately, it is not necessary to harvest squid to obtain the SRT proteins as they can be biosynthetically produced since having their genome sequenced. The SRT-inspired monomer is repeated to create a polymeric chain and the resulting protein that is produced is named accordingly as tandem repeat (TR) proteins.

Figure 3. The Squid ring teeth of a giant squid. Wikipedia Commons

Figure 4. Optical images of squid ring teeth (SRT) and the six common squid species they originate from. Source

Films produced with SRT proteins consist of disordered domains that provide elasticity and flexibility to the materials in addition to ordered domains such as β-sheets that provide mechanical strength. One study designed four TR proteins denoted as TR-nX where X was the number of repeat units within the molecule. They measured the mechanical force of these four TR proteins and found that the ultimate strength of the protein’s scale linearly, with TR-n25 reaching an ultimate strength of 40 MPa. As seen in Figure 4 below, there is a limitation of the study due to sample size. The error bars of the TR-n12 and TR-n25 overlap, so it is not possible to say there is a statistically significant difference from each other.

Figure 4. Mechanical testing of fully hydrated TR proteins (inset shows 1/n dependence) Source

Additionally, SRT protein films have been suggested as a potential solution to the issues related to the release of microfibers into the water from washing. A cloth made from polyester was coated with an SRT protein film and was found to dramatically increase the cloths resistance to abrasion (and microfiber release) compared to cloths that were not coated with SRT protein films.

While there is still a lot of further research to be done, SRT-based proteins are a promising avenue for making our world a little bit less plastic.

~Isla

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Polyester Suits: a Fashion and Environmental Faux Pas

Posted on March 7, 2019 by | 7 comments

Although polyester suits are no longer a fashion statement like they were in the ’70s, polyester and other synthetic materials such as nylon are still very popular materials used to make clothes due to their accessibility, durability and cost-effectiveness. Polyester, nylon and acrylic fibers are among the most popular synthetic fibers on the market. As their name would imply, synthetic fibers are manmade, synthesized fibers and are petroleum-based products.

Figure 1: The manufacturing process of synthetic nylon fibers. Source: Japan Chemical Fibers Association

One of the advantages and appeals of synthetic fibers is that they can be made using recycled materials. This recycled material can be old polyester materials themselves or can even be old plastic water bottles or other recyclable plastic products. There are many companies actively working to use recycled materials to make their apparel and while this may seem beneficial and an excellent solution to fully utilize plastic products to their full potential, it may actually be a double-edged sword. More people could be inclined to use plastic products, as they would assume that the plastic will be recycled properly. Unfortunately, that is not often the case. Not all the plastic products on the market are recycled responsibly and instead can contribute even more to the growing plastic pollution and microplastic issue as mentioned in my previous post. But even when plastic IS effectively recycled to make new fabric, there still is another hidden micro problem, a microfiber problem.

Figure 2: The cycle of synthetic polyester apparel made from recycled materials. Source: Japan Chemical Fibers Association

The video above outlines the not so micro issue surrounding microfibers.

Essentially, every time you wash a piece of clothing made of synthetic materials, tiny fibers or pieces of plastic, called microfibers are released. These microfibers are a type of microplastic since they are essentially micro pieces of plastic. It causes an issue due to the microfibers being too small and bypassing the filters in both our washing machines and at water waste treatment sites.

Figure 3: The estimated amount of fibers released from every wash for three synthetic fibers commonly used in the textile industry. Source for data.

This study estimates the amount of microfibers released (in mg) after the first five washes of 6 kg (the weight of a typical load of laundry) of three different types of commonly used synthetic materials. Figure 4 illustrates the data from their study. While looking at this data, it can be concluded that after the first five washes, the number of microfibers released decreases. However, other studies conclude the opposite—that the amount of microfibers released actually increases the more that the clothing items are washed due to the degradation of the product and the loss of structural integrity.

Figure 4: The amount of fibers (in mg) released from washing 6 kg of synthetic material. Source for data.

So, what can be done to mitigate the amount of microfibers entering our waterways and contributing to the alarming microplastics issue? Some studies suggest implementing better, higher quality filters in waste treatment plants and found them to be extremely effective at trapping these microfibers, decreasing the amount of microplastics entering waterways by 98%. Additionally, there have been other suggestions that include using proteins found in squids to make a biomaterial that can be used to make fabrics. The simplest solution, however, is to just be more conscientious about the products you purchase. By looking for products that have blends of both synthetic and natural fibers not only can recycled materials be incorporated, but also the integrity of the fabrics is improved to prevent less microfiber shedding, leading to the best of both worlds.

~Isla

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Microplastics No Longer a Micro Issue

Posted on January 27, 2019 by | Leave a comment

You wake up in the morning and then press snooze on your alarm clock one more time before groggily dragging yourself out of bed to the bathroom. Quickly you brush your teeth with your electric toothbrush, then hop in the shower and lather yourself with the bottle of that fancy body wash with the microbeads in it. In the kitchen, you grab the lunch you made from the prepackaged salad mix before heading out the door. Now in your car, you turn some knobs on the dashboard to play some music on your way to work or school. In case you have lost count, you have already encountered half a dozen plastic products and it isn’t even 9 AM yet.

Polymerization of ethylene to form polyethylene
Source: Image © Eugbug

Plastics are the result of taking petrochemical monomers (such as ethylene) and converting them to long chain polymers. This is done through a process called polymerization which is relatively easy and cheap to do. Another process, called photo-oxidation occurs as a result of exposure of these long-chain polymers to UV radiation (from the sun) and oxygen (in the air). Essentially, this process causes plastics to become brittle and in combination with the elements (wind and water abrasion), causes the degraded plastics to break into minuscule pieces. When these pieces are between 0.1 and 1000 μm in size, they are referred to as microplastics.

How microplastics are produced and introduced into the food cycle. Roy Cooper/The National

Due to plastics being such a cheap and omnipresent resource, there has been little incentive to recycle such products, leading to an accumulation of plastic waste in landfills and the world’s oceans. It is tragic to see seawater bodies filled with plastic, but only recently has it come into light that these microplastics are starting to make their way into our own bodies too. While seemingly obvious, microplastics have been reported in seafood, but they are also found in fertilizers and in common food items such as beer, sugar and salt. One study from last year found microplastic particles in 17 salt brands from 8 different countries. Additionally, atmospheric fallout of microplastics has also been reported, so it’s very possible we have already been inhaling and consuming microplastics.

A (a) polyisoprene/polystyrene, (b) polyethylene, and (c) pigment (phthalocyanine) fragment. Image (d) is a nylon-6 filament. Source

So what can be done to mitigate the amount of plastic that is becoming ocean waste and effectively microplastics? Our daily lives and plastic products have become too intertwined to even entertain the thought of completely banning plastics worldwide. Fortunately, there have already been movements to ban especially harmful products such as microbeads found in many skin products. But, some effective steps that everyone can implement into their routines are to reduce the use of single-use plastics such as plastic straws or plastic grocery bags. The issue with single-use or “disposable” plastics is that they are difficult to recycle and thus only contribute to plastic waste. Additionally, choosing products that have less plastic packaging is also a viable way to lessen your plastic consumption. Lastly, whenever possible, recycle your plastic products so your plastic water bottle can become a new plastic water bottle and not the microplastics in our food.

The following video is a collaboration between BBC Earth Lab and Exeter University and shows how microplastics can make it through the food chain and potentially onto our plates.

~Isla

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