Tough Epoxy Networks With Dynamic Acylhydrazone Bonds for Recyclable Carbon Fiber-Reinforced Composites

Area of Science:

• Materials Science
• Polymer Chemistry
• Sustainable Engineering

Background:

• Carbon fiber-reinforced composites (CFRCs) are essential in many industries but pose significant recycling challenges due to thermosetting epoxy resins.
• Current methods for recycling CFRCs are often inefficient or environmentally taxing.
• Incorporating dynamic bonds into epoxy networks offers a potential solution for CFRC recyclability, but balancing mechanical strength and degradation remains difficult.

Purpose of the Study:

• To develop robust, recyclable epoxy networks for CFRCs using dynamic acylhydrazone bonds.
• To achieve high mechanical properties, reprocessability, and efficient degradation under mild conditions.
• To enable the recovery of high-quality carbon fibers and reuse of the epoxy matrix.

Main Methods:

• Synthesis of a novel acylhydrazone-containing diamine curing agent.
• Curing of epoxy resin with the synthesized agent to create robust networks.
• Evaluation of mechanical properties, reprocessing stability, and degradation behavior under mildly acidic conditions.

Main Results:

• The developed epoxy networks exhibited excellent chemical and solvent resistance.
• High tensile strength (up to 106.9 MPa) was achieved, with significant retention (> 75 MPa) after multiple reprocessing cycles.
• Efficient recovery of intact carbon fibers comparable to virgin fibers was demonstrated via C═N bond cleavage under mild acidic conditions.

Conclusions:

• The study presents a sustainable approach for recycling high-performance epoxy networks and CFRCs.
• The developed materials combine high strength, reprocessability, degradability, and recyclability.
• The findings pave the way for more environmentally friendly composite materials and circular economy solutions.