Material characterization of recycled and virgin carbon fibers for transportation composites lightweighting

Research results revealed that controlled thermal re-exposure of preconsumed recycled carbon fiber (RCF) increases the formation of a graphitic core and consequently a higher modulus recycled carbon fiber. Furthermore, formation of acidic functionality on carbon during thermal treatment led to improved adhesion with plastic. Transportation lightweighting is shaping the future of mobility and becomes focus of many original equipment manufacturers (OEMs) for many segments as an answer for efficient products. Thermogravimetric analysis (TGA) showed that RCF can resist temperatures up to 400°C without surface degradation, 50°C lower than virgin carbon fiber (VCF), and total treatment weight loss was measured. Fourier-transform infrared spectroscopy (FTIR) results showed acidic groups on thermally treated RCF surface that improved chemical adhesion compared with non-treated RCF. Finally, X-ray photoelectron spectroscopy (XPS) showed the oxygen/carbon ratios, and its perspective deconvolutions were compared with FTIR results. Lower C1s content was found on RCF structure because of thermal treatment. XPS results evidenced the formation of aromatic carbon rings during thermal treatment, further supported by thermogravimetric results. Thus, the thermal process promoted increase in the formation of a graphitic core and consequently a higher modulus RCF.