We are aware that plastics are a very important group of materials for modern technology, the problem is that once they serve their purpose, most plastic items are discarded and the processes to recycle them are very limited.
Today we depend on many plastics that are difficult to recycle. Image credit: piqsels.com.
In this regard, a group of researchers at the University of Konstanz has developed a much more sustainable method for recycling plastic materials similar to polyethylene. The researchers have developed a chemical method to depolymerize plastic molecules down to their monomers, i.e. disassemble the plastic down to its simplest molecular components. This new chemical method works better than mechanical recovery methods, offering a 96% recovery rate of the starting material in an energy-efficient procedure than the established mechanical recycling process, which requires temperatures above 600 °C and is limited by an ethylene recovery rate of about 10%. The results of the research were recently presented in the journal Nature.
The inferior performance of the established procedures is due to the fact that plastics are combined with additives during their manufacture, which contaminate them and alter the properties of the recycled materials, so that with this alternative chemical depolymerization called "breakpoint" the crystalline structure of polyethylene is not altered and the desirable properties of the processed materials, such as those of high-density polyethylene, are fully preserved after recycling.
On the other side, this molecular level breakpoint procedure allows to deconstruct the polymeric chain into smaller molecular building blocks, then, the initial polymers are the result of the polycondensation of these building blocks in which polymers derived from renewable sources such as vegetable oils can be incorporated, and the method only requires temperatures of only 120 °C, this allows a more energy efficient procedure and a closed loop recycling of materials similar to polyethylene, one of the most used plastics.
An idea of the closed-loop recycling process. Image by @emiliomoron.
This type of method is very important for our world, as it is difficult to find easy replacements for plastic materials in today's world for the many applications they have achieved, so we need ways to recycle these materials and recover valuable raw materials that would otherwise end up polluting our soil and water. Without a doubt, efficient recyclability is an important aspect to consider in any plastics technology being developed today.
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