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• Thermochemical recycling of epoxy matrix composite materials with Diels-Alder bonds

  I. Lorero, C. Bravo, M. Campo, A. Jiménez, S. Prolongo, I. Lorero

  Materiales Compuestos (2024). Vol. 08 - COMUNICACIONES MATCOMP21 (2022) Y MATCOMP23 (2023), (Núm. 4 - Sostenibilidad y Reciclaje), 19

  
  

  Abstract

  The high cross-linking degree of thermosetting resins, which gives them remarkable mechanical properties, also implies an irreversible structure that impedes proper recycling at the end of life. This problem influences both thermosetting matrices and composite materials, since the crosslink irreversibility of the matrix hinders the recovery of the fibers. One way to solve this problem is the development of new thermosetting resins that incorporate Diels-Alder thermo-reversible bonds. The introduction of Diels-Alder bonds allows thermosets to have a polymeric network capable of disengaging at temperatures above 90 °C, acquiring certain fluidity and recyclability. However, its composition and curing cycle must be carefully adjusted to avoid undesired chemical reactions and to maintain certain mechanical properties, since the addition of Diels-Alder bonds in high contents usually results in a notable embrittlement of resin. In the present work, the manufacture of an epoxy matrix composite material with 60% Diels-Alder bonds reinforced with carbon fiber is developed, which shows mechanical properties similar to those of a conventional epoxy resin laminate. After that, the recovery of the fiber is addressed thermochemically by dissolving the matrix in dimethyl sulfoxide at 150 °C, achieving the reuse of the fiber to manufacture new composite materials with mechanical properties comparable to the original.

  Abstract
  The high cross-linking degree of thermosetting resins, which gives them remarkable mechanical properties, also implies an irreversible structure that impedes proper recycling [...]

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