Resorcinol-Derived Vitrimers and Their Flax Fiber-Reinforced Composites Based on Fast Siloxane Exchange.

Natural fiber-reinforced composites are gaining increased interest for their significantly reduced carbon footprint compared to conventional glass or carbon fiber-based counterparts. In this study, we use natural fibers in a resorcinol-based epoxy resin that is thermally reshapable at higher temperatures (>180 °C) by using fast exchanging siloxane bonds, catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). Stress relaxation times of only about 6 seconds at 220 °C have been reached. A resorcinol-based epoxy compound is selected because it can be derived from cellulose, opening ways for more sustainable and reshapable composite materials. In a last step of the research, the low viscosity vitrimer formulation (<200 mPa.s) is applied to make a flax fiber-reinforced composite using an industrially relevant vacuum-assisted resin infusion process. A section of this composite has been successfully reshaped, which allows for envisioning a second life for natural fiber-reinforced composites. This article is protected by copyright. All rights reserved.