Novel insights into the correlation composition-structure-property of recyclable carbon fiber reinforced thermosetting resin composites

As widely used lightweight and high-strength materials, the sustainable development of thermosetting composites is hampered by their limited recyclability. Developing simple methods for the efficient and upgraded recycling is desirable but challenging. Herein, carbon fiber reinforced degradable thermosetting resin composites were prepared, and the effects of resin degradation process and its derivatives on the sustainable recycling of carbon fiber were studied. Through the tunable departure and re-adsorption of degradation derivatives in cleaning post-treatment, recycled carbon fibers achieved not only non-destructive recovery but also simultaneously improvements in tensile strength from 3.0 GPa to 3.7 GPa and surface energy from 47.2 mN/m to 66.7 mN/m. The adhered derivatives, rich in -NH- and oxygen-containing groups, exhibited good interactions with the fiber surface and epoxy resin. Benefiting from this, the inter laminar shear strength of recycled carbon fibers reinforced epoxy composite effectively improved 24.3 %. In this work, directly reusing resin degradation products for the recycling of reinforced fibers was proposed and the key role of the composition and distribution of degradation products in recycling properties was revealed. The strategy of integrating characteristics of components to enhance material recyclability is expected to have widespread applicability, promoting the sustainable transition for thermosetting composites.