Environment / 13.06.2019

Professor Kim Ragaert rehabs plastics

Professor Kim Ragaert rehabs plastics

PhD in Polymer Engineering Kim Ragaert, professor on materials science and polymer processing at the University of Ghent (Belgium), offered in this city on April 25 an interesting TEDx talk entitled ‘Plastics Rehab’, which we strongly recommend.

Indeed, we must get “rehab plastics” so that it does not continue to make a “blind war against them for being the most visible abandoned material.” With this last phrase Ragaert ends his reflections, which began with this one: “Why does no one blame metals, that they do not degrade in the environment?”.

2 grams of plastic film wraping a cucumber allows to extend its conservation from 11 to 26 days with the consequent prevention of food waste and CO2 derived emissions: if that “plastic skin” is not used, CO2 emissions would be multiplied by five.

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, is 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 we focus on banning plastics the environmental effects will be devastating”

On the other hand, if we compare a plastic bag with a paper bag, in order to transport the same weight, it is necessary to use 20 grams of virgin plastic versus 50 grams of recycled paper. Since paper requires much more energy, water, land and trees for its manufacture and recycling, it would be necessary to reuse the paper bag 4 times to compensate for the environmental impact generated in its production, which is practically impossible due to its fragility and breakage. And in the case that the bag was made of cotton, the compensation of the environmental impact generated in its manufacture would not be achieved until it was used 173 times due to the intensive use in water and soil that is made in the cultivation of cotton. That’s why the best option is the reusable plastic bag that with 20 uses allows to generate positive environmental benefits.

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 leave the car and the fine for those who leave it. Studies show that 80% of abandoned waste, what we know as “littering”, come 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 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.

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.

We hope you enjoy the talk!