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G2B srl - “Polyethylene-derivative” silk from Galleria Mellonella cocoons

Product Name

“Polyethylene-derivative” silk from Galleria Mellonella cocoons.

 

What Made You Decide to Design This Product and Choose to Use Recycled Plastic Content? :

Almost 350 million tonnes of plastics were produced in 2017, and its demand is going to increase even further in the next years, as all the macroeconomical indicators suggest. According to 2017 data, Europe is the second largest producer of plastics, with over 60 million tonnes of plastics produced a year, most of them used for packaging (40%). Even though the recycling rate in every country has increased in the past years and still is increasing, especially for packaging for which the average EU recycling rate is close to 41%, a lot of work still has to be done. Polyethylene (PE) plastics are quite tricky to dispose of due to the chemical nature of PE. PE is made of a linear backbone of carbon atoms and it is resistant to degradation. Although PE was believed not to be susceptible to bio-degradation, in 2017 researchers from the Cambridge University and the Universidad de Cantabria discovered a very simple yet innovative way to dispose of PE plastics: to be a food for the wax worm of the wax moth Galleria Mellonella. We focused on the simplest product that could be obtained from the growth of a larvae: that is its cocoon and the silk that can be spinned from it. Having described the context, the reason why we focused on this project is straightforward: here, we are not “technically” using recycled plastics, we are completely transforming it into a new product, which is silk, by feeding the wax worms. This could lead to a brand new usage of PE plastics and a brand new, ecological and sustainable way to dispose of it.

 

What Were They Key Outcomes and Objectives That Lead You to Design This Product? :

It is indeed true that silk can be generally considered as a raw material, not technically a “finished product”. But, in our case, the perspective is different, since silk is the true product of an innovative and bio-compatible process that involves the bio-degradation of PE plastics. Even though we are currently testing the tensile properties of the silk spinned from the Galleria Mellonella cocoons, we found that it has excellent mechanical properties from literature data. Thus, we believe that cocoons can be spinned without any problems, and then used for tensile applications.

 

Outline The Development Phase of the Design:

Wax worms were fed with pieces of low density PE (LD PE) along with particular food, made of beer yeast, glycerol, honey and bran. The temperature of the room was constantly monitored and mantained above 20°C, so the worms would be in the right conditions to spin their cocoon and enter the pupa stage of their life cycle. Since the worms prefer dark conditions to grow, they were kept inside a box covered with a thermal insulating material. The pupa stage is achieved relatively fast with the correct diet, so that the cocoon can be obtained and spinned. The Galleria Mellonella cocoon is quite from the most used one, the Bombyx Mori cocoon since it is smaller and not as thick as it is, meaning that more cocoons are needed to get the same amount of tensile fibres.

 

How Did You Monitor and Meet the Objectives That You Set? Where Appropriate Include Information On Research, Resourcing, Speed-To-Market, Material Selection, Testing and So On:

Galleria Mellonella worms were bred during the past months and were fed with an appropriate food made of beer yeast, glycerol, honey and bran, which was revealed to be the most efficient. We tested on our own the ability of the worms to eat and digest PE LD plastics from packaging by monitoring the shape and the weight of the plastic pieces, as was done by the researchers (Polyethylenebio-degradation by caterpillars of the wax moth Galleria mellonella, Bombelli P., Howe G.J., Bertocchini F., Current Biology Magazine, 2017). From the hatching of the eggs to the pupa stage (that is approximately when the cocoon is formed) it takes about a month. From literature and empirical data, we also found that the worms live longer if kept at 20°C. As said above, we are currently testing the tensile properties of the silk fibres obtained from the cocoons. All the physical and chemical analysis that supported our reasearch, for example on the worm residues, were conducted within our company, G2B srl.

 

What Is Special About The Design?

As mentioned above, the very possibility to convert PE into a new material, silk, is of great interest per se. The product, due to its tensile properties, could be easily used for a lot of applications, the most obvious being clothing. Unlike the Bombyx Mori, the most common silkworm, Galleria Mellonella is relatively easy to feed, since its diet is less specific than the Bombyx Mori one, aside from the fact that the latter cannot digest PE. In addition to that, we are positive about the fact that breeding Galleria Mellonella instead of Bombyx Mori would be remarkably less expensive. Again, we stress the fact that we are not using recycled plastic, we are concretely transforming into a new material, by fact reducing the quantity of plastics that needs to be disposed of, which may be seen an “upgrade” of the simple recycling.

 

Please Include What In Your View Makes Your Recycled Plastic Product Innovative:

We really think that our product, that is the silk spinned from Galleria Mellonella (GM) cocoons, has a very powerful innovative nature. Being able to convert polyethylene plastics to a completely different and biocompatible material, that is silk, is indeed a step forward to the conventional recycling techniques, which simply convert plastics to plastics. Silk can then be used for lots of applications, including clothing and medical purposes. We are currently investigating the Galleria Mellonella silk tensile properties: clothes made from GM silk would have a very high degree of innovation, being a sustainable, eco-friendly alternative to the Bombyx Mori silk. The process in its entirety can be ultimately seen as an application of circular economy.

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