24 December, 2019 Sustainability

Plastics rehab: Kim Ragaert on the science of materials

Why are cucumbers wrapped in plastic? At first sight, it may look like a lot of waste and an endless source of pollutant emissions, but there are many small details behind this fact that should be taken into account before we discard plastic packaging as terrible waste.

Polymers Engineering Professor at Belgium’s University of Ghant, Kim Ragaert, gave a TEDx talk entitled ‘Plastics Rehab’ on materials science and polymer processing.

In the talk you can watch here, Kim Ragaert explains how, in the cucumber example, that ‘plastic skin’ could mean a fivefold reduction in CO2 emissions. How?

The idea is simple but also big. With the 2-gram plastic film wrapped around the cucumber, we manage to preserve it for double the time, from 11 to 26 days, which means a significant reduction in food waste and associated CO2 emissions.

The conclusions drawn by the fundacionplasticsense.eu on Kim Ragaert’s words are as follows.

‘Plastics are extremely light materials. They have half the density of glass and a density similar to paper but being very resistant they can be manufactured with minimum thickness compared to other materials. This means that in their manufacture, they consume much less resources and that they are much more efficient in their transportation. Thus, to pack the same amount of liquid you need 24 times more glass than plastic and twice as much fuel is consumed if it is transported. And it is true that it is possible to reuse a glass bottle up to 8 times, but even just recycling 50% of plastic bottles, we are still using 6 times more material in the case of glass than plastic. Additionally, the melting temperature of the glass is about 1,500 when the plastic temperature is around 300 , so the energy to make a glass bottle is much higher than that needed to make a plastic bottle. In conclusion, the plastic manufacturing and recycling system is, on the whole, infinitely more efficient than glass.

If someone leaves a car in the middle of the street, do we blame the car? Do we ban cars? The fault lies with whoever leaves the car and the fine should go to those who leave it. Studies show that 80% of abandoned waste, what we know as “littering”, comes from ourselves, from consumers.

If we focus on banning plastics the environmental effects will be devastating because to produce products that meet the same functionalities, the amount of material, energy consumed and CO2 emitted will be double or even threefold. That is, we will be substituting plastic for less sustainable alternatives and there will be a paradox that the impact on the environment will be much greater. Just the opposite effect that was looked for in the first place.

Consumers have the power to avoid this through the purchase of recyclable products which contain recycled material and providing these products with an appropriate end of use by depositing them in the selective collection containers.