A Quantitative Model Investigation on Degradation of CF/EP Composites

Abstract

The high performance carbon fibers could be obtained from wastes of CF/EP composites by thermal excitation of Cr₂O₃. Recycling experiment was designed by response surface method to investigate quantitative model, then quantitative relationship between degradation ratio of epoxy resin and process parameters was established based on the higher order response model. The effect of process parameters on degradation ratio was analyzed by graph optimization. The morphology, surface elements and functional groups, and mechanical performances of the recycled carbon fiber were analyzed and characterized under optimal process parameters. The results indicated that the error of the quantitative model was within ±5 % for wastes of leftover materials, and the error was within ±11 % for wastes of composite products; the effect degree of process parameters on degradation ratio: temperature > treatment time > O₂ concentration > O₂ flow; the optimal process parameters were temperature of 500 °C, treatment time of 25 min, O₂ concentration of 80 % and O₂ flow of 180 ml/min; the surface microlite of the recycled carbon fiber underwent oxide etching resulting in a slight graphitization; the ratio of O to C content of the recycled carbon fiber decreased by 16.67 % compared with the original carbon fiber, and monofilament tensile strength was 108 % of that of the original carbon fiber.