Hydrothermal depolymerization of carbon-based composites

Elsa Weiss-Hortala (1) , Yi Rong (1) , Andréa Oliveira Nunes (1) , Yannick Soudais (1) , Radu Barna (1)

1 RAPSODEE - Centre de recherche d'Albi en génie des procédés des solides divisés, de l'énergie et de l'environnement

The global demand of carbon fiber is increasing, therefore an increasing amount of carbon fiber reinforced polymer waste is produced. Carbon fibers are high added value materials which would be recycled at the composite end of life to offer positive impacts on environment and economic development. Hydrothermal treatments in water or in solvents are also gaining more attention to recycle carbon fibers and valorize polymer matrix into useful materials at the same time. This study focuses on the impact of operating conditions on the depolymerization of the matrix and on the surface quality of the fibers. Carbon fibers reinforced PA6 (thermoplastic polymer, 45 wt. %) are depolymerized in sub and supercritical water (Tc=374°C and Pc=22.1MPa). The experiments were carried out in batch reactors of 5mL at various operating conditions. The whole operating conditions are suitable to remove the polymer from the carbon fibers. A minimum of 39 wt. % of resin is removed in all cases after 30 min treatment while the surface quality of the fibers remains close to their virgin state. The increase of pressure and temperature favors the kinetics, however reaction time plays an important role on the carbon distribution. Indeed, repolymerization reaction (carbonization) is supposed to occur and discussed.

Domaines: Polymères; Génie chimique

Elsa Weiss-Hortala, Yi Rong, Andréa Oliveira Nunes, Yannick Soudais, Radu Barna. Hydrothermal depolymerization of carbon-based composites. 14th European meeting on supercritical fluids, May 2014, Marseille, France. ⟨hal-01725213⟩