Reprocessable and repairable carbon fiber reinforced vitrimer composites based on thermoreversible dynamic covalent bonding

Abstract

The emergence of vitrimers breaks through the limitation of traditional carbon fiber reinforced thermoset composites (CFRP) caused by their permanent crosslinking molecular networks. Herein, the dynamic cross-linked network of vitrimer was synthesized from Bisphenol A diglycidyl ether (DGEBA) and glutaric anhydride (GA) under the catalysis of zinc acetylacetonate (Zn(acac)₂), and the corresponding carbon fiber reinforced vitrimer composites (CF/V_x) were prepared via an impregnation and hot pressing process. The dynamic covalent adaptable networks (CANs) of vitrimer endow CF/V_x with stress relaxation and creep characteristics. By adjusting the catalyst content, the dynamic performance of CF/V_0.05 can be optimized to achieve the highest viscous flow activation energy (60 kJ/mol) and the lowest characteristic relaxation time (1.0 × 10⁻³ s). The unique dynamic properties enable CF/V_x with reprocessability at high temperature. Typically, the flexural modulus of CF/V_0.05 decreased from 87 ± 1.81 GPa at room temperature to 4.62 ± 0.28 GPa at 220 °C, which confirms the feasibility of thermoplastic forming of CF/V_0.05 at high temperatures. Based on this, a CF/V_0.05-based cap-shaped component was successfully manufactured through a thermoforming process. Additionally, the CF/V_0.05 composites also exhibit repairability for interlaminar fractures. The optimal CF/V_0.05 can achieve a repair efficiency of 128 % under the hot press conditions of 180 °C, 10 MPa and 1 h. Hence, the reprocessable and repairable CF/V_x composites hold enormous potential in the engineering field.