Thermochemical recycling of epoxy resin composites reinforced with carbon fiber

Abstract

The aim of this study was to recovery carbon fiber present in composite materials with epoxy resin matrix using a thermochemical recycling way. A full factorial design was proposed with two factors: the degradation temperature (DT) and the number of thermal baths (NB), which were evaluated in a range of 600°C–650°C and 0–2 baths, respectively, for 30 min. The responses were burn-off degree (BO) and tensile strength. The BO indicated that the temperature as well as the number of thermal baths have positive effects and, therefore, contribute to the degradation of the epoxy resin. Regarding the tensile strength, higher DT promotes a more pronounced effect in that response, but its interaction with NB causes greater damage to the surface of the carbon fiber. A new recycling condition was evaluated and compared with commercial carbon fiber. The results of tensile strength indicated it is possible to test similar applications for both recovered fiber and commercial fiber. The morphological characterizations showed that recycled materials preserved their physical structure, and all surface groups were removed throughout the thermochemical degradation process. In addition, the SEM analyzes indicated the preservation of the wefts after recycling, although residual matrix and the beginning of sizing destruction were observed. Thermochemical recycling proved to be an effective and better way to reuse carbon fiber instead of landfill and incineration.