Chemical Recycling of Carbon Fiber Reinforced Epoxy Resin Composites via Selective Cleavage of the Carbon–Nitrogen Bond

Abstract

An efficient strategy is developed for chemical recycling of cured epoxy resin (CEP) from its carbon fiber reinforced polymer composites (CFREP) using AlCl3/CH3COOH as the degradation system. Acetic acid swells the dense structures of CEP, facilitating the penetration of the aluminum ion catalyst into the polymer matrix. The weakly coordinating aluminum ions in CH3COOH solution selectively cleave the C–N bond while leaving the C–C, C–O (aryl alkyl ether) bonds intact. This process recovers valuable oligomers and carbon fibers from CFREP.

Recycling of carbon fibre reinforced plastics by electrically driven heterogeneous catalytic degradation of epoxy resin

“…SI1 †). Fluidized bed [16][17][18] Solvolysis [9][10][11][12] Supercritical/ subcritical [13][14][15] Facility CFRP was purchased from Carbon Composites Company Limited (Hong Kong) with an epoxy resin content of 31.5%. Each layer of CF cloth is made by orthogonal weaving of longitudinal and transverse CFs.…”

“…5h, the surface of the CFs has deteriorated due to oxidation and exhibits pits and crack defects. 10,13,14 When the tensile test is conducted on a single fibre, this part becomes the critical section, and the stress concentration occurs near this section. Finally, fracture failure occurs in this section.…”

“…Although the CFRP materials reach the end of their service life, the CFs themselves generally retain their properties; 4 therefore, the prospect of recycling CFRP composites without damaging the mechanical properties and dimensions of CFs is of great commercial interest. The recovery value of epoxy resin is not comparable to that of CFs; thus, in recent years, a great number of studies have been conducted on the reclamation of CFs from composite wastes, including mechanical recycling such as shredding and milling, 5,6 pyrolysis at high temperature, 7,8 chemical decomposition using solvents such as methanol, ethanol, 1-propanol and acetone, [9][10][11][12] chemical recycling under sub-/supercritical conditions, [13][14][15] decomposition in high-temperature fluidized bed processes [16][17][18] and an electrochemical recycling method. 19 However, as shown in Table 1, the existing techniques generally suffer from various drawbacks such as requiring complicated processes and superior facilities, pollution generation and damage to the CFRP waste.…”

A Sustainable Approach to the Low-Cost Recycling of Waste Glass Fibres Composites towards Circular Economy

“…Focusing on sustainable and green chemistry aspects [26][27][28][29][30], chemical methods which are based on supercritical solvents in which an organic solvent or water with or without catalysts are the most promising methods. These methods can retain fibre strength up to >90% and generate a limited quantity of by-products and wastes [31][32][33][34][35]. Nevertheless, they are still considered high energy-consuming processes because of the fact that reaching the supercritical status of solvents requires high processing temperatures and extremely high pressures.…”

Hybrid biobased recyclable epoxy composites for mass production

“…Chemical recycling is however attracting increasing interest within the composites manufacturing community due to the possibility to obtain clean reclaimed fibers and, in some cases, valuable monomers from the epoxy matrix . Chemical recycling methods have been presented by several authors , and most recently the use of acetal links was reported as a way to develop recyclable epoxy composites . Kuang et al have described a reversible cross‐linked epoxy resin with efficient reprocessing properties prepared from a diamine Diels‐Alder adduct cross‐linker and a commercial epoxy oligomer .…”