High strength, self-healing and hydrophobic fully bio-based polybenzoxazine reinforced pine oleoresin-based vitrimer and its application in carbon fiber reinforced polymers

The traditional carbon fiber reinforced polymers (CFRPs) matrix is a permanent 3D cross-linked network that is difficult to degrade and reprocess. In order to solve the closed-loop recycling of carbon fibers (CFs) and develop green economy. We synthesized aldehyde-containing bio-based benzoxazine (VD) from vanillin and 1,10-diaminodecane, the epoxy resin vitrimer matrix (P-AE-MV) was prepared by curing acrylpimaric acid diglycidyl ester (AE) with a Schiff base (MV) formed by 1,8-menthane diamine (MDA) and VD. Under the double dynamic covalent bond of Schiff base and β-hydroxy ester, P-AE-MV has a very low dynamic bond exchange activation energy Ea = 48.1 kJ mol−1, which can realize the rapid topological rearrangement of polymer network, and give P-AE-MV excellent self-healing, shape memory, reprocessability and degradability. In addition, the introduction of polybenzoxazine (PBz) structure greatly improved the mechanical properties, thermal decomposition temperature, carbon yield and hydrophobicity of epoxy resin vitrimer, which is very suitable for CFRPs matrix. The CFRP (P-AE-MV-CF) prepared with P-AE-MV as matrix resin have good mechanical properties, reprocessability, shape memory and self-adhesion. Especially, it can be rapidly ammonolysis with n-butylamine under mild conditions (60 °C), achieving efficient and non-destructive recycling of CFs. This work provides an effective solution to promote the closed-loop recycling of CFs and the sustainable development of CFRPs using fully bio-based resources as raw materials.