Qu & Bai et. thermally pretreated PET with pyrolytic lignin because PET has 15-20% carbon content, which helps synthesize condensed carbon fibers. The obtained precursor was highly viscous and contained phenolic molecules derived from lignin. Moreover, it was thermally stable and had a higher molecular weight and enhanced processability compared with those of the precursor without PET. Melt spinning was used for converting the precursor into precursor fibers. Then stabilization at a rate of 0.3°C/min at 260 °C. The fibers were then carbonized at 1000 °C at a rate of 3°C/min. The resulting carbon fibers were 1.220 GPa at maximum strength and 0.925 MPa on average.