Influence of treatment with superheated steam on tensile properties of carbon fiber

The influence of treatment with superheated steam (SHS) during the recycling of carbon fiber reinforced plastics was assessed by exposing unidirectional carbon fiber reinforced (UD) sheets to SHS under various conditions. The thermal behavior of UD sheets was identified through thermal analysis. The polymer decomposition was clarified microscopically and based on the weight reduction. Carbon fiber recovery was optimal after treatment at temperatures higher 650 °C as well as at relatively lower temperatures when 4 vol% O2 was used. The effects of SHS on the fibers were evaluated by comparing the tensile properties of the recycled carbon fibers (r-CFs) with those of corresponding virgin ones. The strength of r-CFs exhibited appreciable scatter, despite the average strength being lower. The cross-sectional area and tensile modulus of the individual r-CFs were approximately equal to those of the virgin fibers. Statistical and fracture surface analyses were performed to elucidate the experimental results.