Recycling of Elium CFRPs for high temperature dissolution: a study with different solvents

Due to the all-encompassing problem of recycling conventional thermoset composites, which neither leads to sufficient matrix recovery nor to the recovery of fibres in satisfactory quality, new thermoplastic matrix systems are being explored for special interest against the background of closed loop recycling. For this reason, the Institute for Polymer Materials and Plastics Engineering at the TU Clausthal is researching the novel matrix system Elium 150 from the French manufacturer Arkema [1, 2]. This system, which is infusible and curable at room temperature, is characterised by a processing similar to conventional thermosetting resin systems with comparable mechanical properties, which leads to a high market potential. In order to prevent the accumulation of waste without a satisfactory recycling method for this material, we are already investigating to develop recycling processes at its market introduction phase. A dissolution based process has been developed which, at room temperature separates the matrix from the fibres within 24 hours [1]. This process allows to recover both the fibres in undamaged form (scrims) and the matrix as well. Both the matrix and the fibre properties of the recycled products can be considered comparable to virgin materials [2]. In order to shorten the process time, the use of higher temperatures for dissolution is a common practice. Therefore as a quicker recycling method the use of microwaves as possible heating source is our next objective. A key factor for this is a temperature resistant solvent. As acetone being volatile raises safety concerns at high temperatures and hence is not a suitable solvent for use in the microwave. Such being the case, this article investigates temperature-resistant solvents, which can be the medium for recycling Elium CFRPs via microwave heating. Solvents being considered are in particular acetophenone, xylene and ethyl acetate to determine their suitability.