Recent trends in recycling and reusing techniques of different plastic polymers and their composite materials

The rising environmental concerns caused by the excess use of synthetic materials have diverted the world's attention towards sustainable materials along with a circular economy approach using recycling routes. Nowadays, composite materials have been enormously utilized in different industrial sectors, thus, causing serious accumulation of plastic waste in the environment. The end-of-life (EOL) treatments for plastic composites are imperative as these materials cannot be easily disposed of. The recycling methodologies adopted for polymer composites have two major advantages. Firstly, recycling techniques control plastic composite waste consumption. Secondly, the energy required in the recycling of plastic composite materials is quite low, compared to conventional manufacturing techniques. In this review, we highlight some recent recycling and reusing techniques adopted for plastics and their composite materials. Among all the reported recycling techniques for polymer composites, thermal recycling is best suited for the recycling of carbon fibers (CFs) and glass fibers (GFs). Through thermal recycling, the properties of recycled materials can meet the properties of virgin materials and energy is significantly lower than chemical recycling. However, mechanical recycling requires very low energy for the recycling of composites as compared to the other recycling process. It was concluded that the composite materials consumption in different industries would only be justified when recycling and reusing of composites should be given equal consideration. Additionally, the recycling of polymer composites will boost the circular economy.