Solvolysis as a methodology for the EoL of thermoset composite materials
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Plastic waste is one of the major threats to our ecosystems as the current end-of-life given to plastics adversely affects the environment. The use of composite materials has gained interest during the last decades due to their unique properties and long durability in a wide variety of applications, such as wind blades, aircrafts, sporting goods, boats, railway industry. This use increment has implied a huge increase in composite waste, increasing the end-of-life issue as over 67% of composite waste ends up in landfills or incinerated, and it will imply an exponential increase in composite waste management as composites aircrafts and wind blades among other composite components reach their end of life. Structural thermoset composites are formed by a combination of a high value matrix and a continuous reinforcement. Current recycling technologies do not allow to revalorize both components while retaining most of their value, implying a downcycling and issues in the reintroduction of the materials into the market. The structure of composites makes them resistant to adverse conditions and therefore hard to recycle in a controlled way. In this study, we have been working on the optimization and adaptation of green solvolysis processes to separate matrix and reinforcement while obtaining from the recycling process high value products, such as continuous fibres and complete textiles. To accomplish the recycling process, several acid-oxidant conditions have been used to boost the breakdown of commercial thermosets. Besides, we have tested green solvents to achieve a low environmental impact, high value process for the recovery monomers and fibres. So far, promising results have been obtained with matrixes used in aeronautics, naval and construction industries as well as with carbon and glass fibres and with natural fibres such as flax.