Is a new type of recyclable plastic just around the corner? Scientists have discovered key properties of glass-like polymers

- Dec 06, 2019-

On November 28th the proceedings of the national academy of sciences published a new paper detailing the latest advances in a new plastic.


35. The JPG


Recently, researchers have discovered a promising recyclable plastic that may one day replace hard plastic, which is hard to recycle.

However, we have yet to see these so-called vitrimers used in any product because they are so difficult to process.


36. The JPG


Star-shaped polymer exchange bonds.

Source: university of technology eindhoven


But researchers at the eindhoven university of technology have found that the processing properties of the new plastic are affected not only by temperature but also by density.

With these new advances in new plastics, researchers should be able to make recyclable dashboards for the automotive industry.


It has long been known that plastic is difficult to recycle and therefore bad for the environment.

However, the hardest plastics to recycle are mainly so-called hard plastics, or thermosetting plastics, such as those used to make billiards and car dashboards.

Thermoplastics, on the other hand, are easy to recycle. They are used industrially to make aluminum foil, coffee cups or toys, but they are much weaker than thermosetting plastics.

In 2011, scientists developed a new plastic, the so-called vitrimer, that is as strong as hard plastic and recyclable.

In 2015, inventors of new plastic materials won the European Inventor award from the European Patent Office.


Mysterious material


Whatever the prospects, glassy polymers are still a long way from commercial use.

To reach this stage of commercialization, manufacturers need to know how to process the new material to get the desired properties.

Scientists, however, remain largely ignorant of how the substance works.


But now, physicist Liesbeth Janssen, PhD student Simone Ciarella, and bachelor of science Rutger Biezemans have demonstrated a computer model that shows how temperature and density affect glassy polymers.

"Now that we have a better understanding of the physical composition of this material, we hope to be able to produce real recyclable plastics for the industry in future projects," Janssen said.


Brittleness determines recycling capacity


Their model show that the type of glass polymer brittle (fragility) is to determine the processing ability of the decisive factors.

"Brittleness is the rate at which a material melts and solidifies," Ciarella said.

"The less brittle it is, the easier it is to process the plastic and therefore the easier it is to recycle the material."


Liesbeth Janssen and her colleagues not only understood and predicted the impact of this brittleness, they also adjusted the brittleness of the new plastic.

The brittleness of the new material can be changed by adjusting the density of the material so that manufacturers can accurately process plastics in the future.


"Connection"


To explain this effect, we need to understand the physical properties of the three plastics in detail.

Plastic is made up of very long wires, which are also called polymers.

Thermosetting plastics are so strong because there are many connections between the polymers, but heating causes these connections to break irreversibly, which explains why thermosetting plastics are less recyclable.

Thermoplastics, on the other hand, have no connections between their polymers, so thermoplastics tend to deform as temperatures rise, making them much weaker.


"But glassy polymers are interesting," Ciarella says. "they have a lot of connections between their polymers, but when heated, these connections can be switched between different polymers.

Therefore, at room temperature, these glassy polymers are as strong as thermosetting materials.

But when heated, they become like easily deformed thermoplastics, so the new plastic retains its mass after melting."