Consequently, the number of plastic components and applications including CNTs has been continuously increasing in the last years. This development has also affected the price evolution (from several thousand to around one hundred euros per kilogram). The toxicity of CNTs and their environmental effects has also been studied, but low attention has been paid on the recycling of plastics containing CNTs. Depending on the applied technical waste treatment, CNTs could be released to atmosphere and water bodies. Recycling plastic scraps from polymers containing CNTs can be an interesting way for recovering CNTs, manufacturing advanced materials at lower costs and additionally preventing the release of CNTs to the environment.
RECYTUBE project focuses on this option, producing advanced polymers from CNT-containing scraps, and makes use of the knowledge acquired in the previous project POLYCOND , which was funded under the European Commission's Sixth Framework Programme (FP6) and addressed the compounding of inherently conductive polymers. The on-going project has been funded under the CIP Eco-innovation Call and is nearly finished. Aimplas, a technological centre from Spain, is leading a consortium which covers the entire value chain for obtaining CNT-containing polymers; a CNT provider, a polymer compounder and a final user from the automotive sector are also involved.
The project activities have also included the entire value-chain, from the polymer scrap to the final recycled polymer. Firstly, a simple and reliable methodology for quantifying the CNT content of polymer scraps has been developed. This method was initially tuned for its application to two common polymers from the automotive (polypropylene) and the electronic (PC-ABS) sectors, but it was extended to PA66 and PBT due to its accuracy. Knowing the exact CNT content of scraps allows tuning the conductive properties of polymers by mixing and blending them with raw polymers. Furthermore, controlling the injection parameters has been a critical issue, since applying inadequate process conditions can degrade the conduction property of CNT-, thus obtaining polymers without magnetic shielding or conductive properties.
Conductive recycled polymers have recently been obtained, achieving the success of the project. Thus, immediate steps will involve the adaptation of processes to specific components and a level of 7 in the TRL scale could be assigned to the project. In a near future the acquired know-how could be licensed to other interested companies under request, although the technologies should be tuned in each case.