Investigation on Curing Kinetics of Recycled Carbon Fiber Reinforced Thermoset Composites Manufactured by Direct Ink Writing

ABSTRACT Recycled carbon fiber (rCF) with excellent performance was obtained based on the thermally activated oxide semiconductor process. The effects of temperature and curing degree on recycled carbon fiber reinforced polymer (rCFRP) manufactured by direct ink writing (DIW) were investigated by rheological analysis and differential scanning calorimetry (DSC). On this basis, the curing kinetic equation of rCFRP was established using the phenomenological kinetic model. In addition, the effects of different rCF mass fractions on the mechanical properties of rCFRP were analyzed under the optimal process conditions. It was shown that the correlation R 2 value of the established curing kinetic equation was about 0.992, which could accurately describe the curing process. When the DIW process temperature was maintained at 99.21°C, the ink exhibited superior form retentivity with a curing degree of 4.82% and viscosity of 41.985 Pa·s. Compared to epoxy resin, the tensile strength and flexural strength of rCFRP with 20 wt% rCF were improved by 116.15% and 65.99%, respectively. The research results lay the theoretical and methodological foundation for the prediction of DIW process parameters and provide a technical way for rCF's high‐value reuse.