Secondary Raw Materials from Residual Carbon Fiber-Reinforced Composites by An Upgraded Pyrolysis Process

Abstract

This paper presents a process where carbon fibers and hydrogen can be recovered simultaneously through a two-stage thermal treatment of an epoxy-carbon fiber composite. For this purpose, some pieces of epoxy resin reinforced with carbon fiber fabrics have been fabricated and, after curing, have been pyrolyzed in an installation consisting of two reactors. In the first one, the thermal decomposition of the resin takes place, and in the second one, the gases and vapors coming from the first reactor are thermally treated. Once this process is completed, the solid generated is oxidized with air to eliminate the resin residues and carbonaceous products from the fibers surface. The recovered carbon fiber fabrics have been reused to make new cured parts and their electrical and mechanical properties have been measured. The results show that it is possible to obtain carbon fiber fabrics that can be processed as they leave the recycling process and that retain 80% of the tensile modulus, 70% of the flexural strength, and 50% of the interlaminar shear strength. At the same time, a gaseous stream with more than 66% by volume of hydrogen can be obtained, reaching a maximum of 81.7%.

Valorisation of Sub-Products from Pyrolysis of Carbon Fibre-Reinforced Plastic Waste: Catalytic Recovery of Chemicals from Liquid and Gas Phases

“…The catalysts were introduced into the tubular reactor in the form of particles in size 0.42–0.5 mm, so that the ratio between the internal diameter of the reactor and the particle diameter was greater than 10, thus avoiding the formation of vial lanes adjacent to the wall [ 22 ]. The catalyst was placed in the middle part of the tubular reactor, where the desired operating temperature was ensured, and mixed with CSi of the same particle size.…”

The Kinetic Study of the Influence of Common Modifiers on the Curing Process of Epoxy Vitrimers

“…Here, A 1 is the pre-exponential factor for the non-catalyzed reaction (1 − α) n , and A 2 is the pre-exponential factor for the catalyzed path (1 − α) n α m . It should be noted that the chosen model (Equation (10)) has an important advantage over the autocatalytic model (5). The constant B in the model (Equation ( 10)), which is the ratio of the pre-exponential factors of two competing reactions with assumed equal activation energies, shows how many times the rate constant of the autocatalytic reaction exceeds the rate constant of the n-th order reaction.…”

“…There is also highly efficient recycling technology utilizing supercritical fluids. However, the most popular but not resilient method commercialized is pyrolysis [9,10]. At present, the economic feasibility of composite recycling lies in the reclamation of carbon fibers.…”

Recycling of Wastes Deriving from the Production of Epoxy-Carbon Fiber Composites in the Production of Polymer Composites

“…This waste has still high mechanical properties and can potentially be used in the formulation of new composites. The main routes to recycling are either mechanical processes, mainly aiming at shredding the composite to obtain a small size filler [3][4][5] which will have lower mechanical properties than the pristine material, or fiber reclaiming, where the surrounding matrix is either pyrolyzed [6,7] or chemically removed in different ways [8][9][10]. Mechanical recycling is possibly the simplest method, while reclaiming implies more complex thermal and/or chemical treatments, which may result in an energy or environmental drawback.…”