We present a rapid fabrication method for fiber-reinforced polymer composites based on heat pressing woven carbon fibers and vitrimer powder. Vitrimer consists of a covalently cross-linked network endowed with dynamic covalent bonds, which can be thermally activated to undergo bond exchange reactions, thus enabling the rearrangement of network topology without impairing its integrity. These bond exchange reactions lead to bulk stress relaxation and interface healing at the macroscopic scale, thereby allowing the vitrimer powder to fuse into a matrix embedded with the carbon fibers through a heat press process. We demonstrate for the first time that vitrimer composite samples can be fabricated within a few minutes (as short as 1 min) under different temperatures and pressures, which is significantly shorter than the time required for typical liquid-state manufacturing methods. Additionally, the malleability of the vitrimer matrix allows the composite to be reprocessed through thermoforming, which can greatly expand the manufacturing capability of fiber-reinforced composites. The fabrication method demonstrated in this paper has the potential to enable high volume manufacturing of fiber-reinforced composites in industrial sectors such as the automotive industry.

Polyimine is a type of covalent adaptable networks, known as vitrimer, endowed with dynamic imine bonds that can reversibly break and reform upon either heat or moisture. Its low topology freezing transition temperature (∼130 °C) and responsiveness to moisture make polyimine suitable for recycling, reprocessing, and repairing under mild processing conditions. Here, we demonstrate the rapid fabrication of carbon fiber-reinforced polyimine composites and their unique properties. Using a powder-based compression molding method, we are able to fabricate carbon fiber-reinforced polyimine within ∼4 min. The resulting composites exhibit similar mechanical properties as the samples prepared through much slower liquid-based impregnation method (>24 h). We also demonstrate in situ, mold-free repair of polyimine composites with a curved surface at low temperature and pressure (∼75 °C, implemented by a handheld iron for 5 min). The malleability, weldability, and full recyclability of polyimine composites fabricated by the powder-based method are also demonstrated. These unique properties offer great promise for expanding the manufacturing capability and extending the service life of fiber-reinforced composites.

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