Recyclable Carbon Fiber Reinforced Vanillin-Based Polyimine Vitrimers: Degradation and Mechanical Properties Study

Both environmental and economic factors have driven the development of degradable resin for carbon fiber (CF) recycling under mild conditions. However, the vast majority of thermosetting materials are difficult to recycle. This paper presents bio-based polyimine vitrimers to fully recycle the CF. The effect of vitrimers fine structures on the thermal, mechanical, solvent resistance, and degradation properties is carefully investigated. The tensile strength at break and Young's Modulus of pure polyimine vitrimers reach ≈80.3 MPa and 2.89 GPa. Importantly, the mechanical property of isophoronediamine-based polyimine vitrimers/two-layers CF exhibits a slightly inferior value to that of bisphenol A epoxy. Polyimine vitrimers are easily degradable under acid solution at 60 °C for 24 h. The surface morphology and chemical structure of CF are not changed after recycling. This work on mildly degradable polyimine vitrimers from vanillin and readily recycling of CF is desirable for the development of eco-friendly CF composites and lignin functional materials.